To change the Quality of Service (QoS) policing action from child first, then parent (the default) to parent first, then child, use the qospoliceorderparent-first command in global configuration mode. To disable the parent-first order and restore the default behavior, use the no form of this command.
qospoliceorderparent-first
noqospoliceorderparent-first
Syntax Description
This command has no arguments or keywords.
Command Default
If the qospoliceorderparent-firstcommand is not entered, the child policing action is done first, followed by the parent policing action.
Command Modes
Global configuration (#)
Command History
Release
Modification
15.1(1)S
This command was introduced.
Usage Guidelines
Prior to Cisco IOS Release 15.1(1)S, in a hierarchical policing policy map (a parent policy with policing configured under a class that has a child policy also with policing configured), the parent policing action was done first, followed by the child policing action.
Beginning in Cisco IOS Release 15.1(1)S, the order is reversed. By default, the child policing action is done first, followed by the parent policing action. This change applies only to software dataplane policer implementations (Cisco 7200, Cisco 7301, and Cisco 7600 FlexWAN and SIP200 line cards).
This new behavior improves the results for transmit-and-drop actions because the child policing action occurs first. However, if the parent and child policers are performing conflicting mark-and-transmit actions, the parent mark takes effect rather than the child because the parent action happens last.
Use of the qospoliceorderparent-first command is necessary only if you need to revert to the police order that was in effect prior to Release 15.1(1)S.
Examples
The following example shows how to change the police order from child first (default) to parent first, then child:
Router# qos police order parent-first
qos pre-classify
To enable quality of service (QoS) preclassification, use the qospre-classify command in interface configuration mode. To disable the QoS preclassification feature, use the no form of this command.
qospre-classify
noqospre-classify
Syntax Description
This command has no arguments or keywords.
Command Default
QoS preclassification is disabled.
Command Modes
Interface configuration (config-if)
Command History
Release
Modification
12.0(5)XE3
This command was introduced.
12.1(5)T
This command was integrated into Cisco IOS Release 12.1(5)T.
12.2(2)T
This command was implemented on the Cisco 2600 and Cisco 3600 series routers.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
Cisco IOS XE Release 2.1
This command was implemented on Cisco ASR 1000 series routers.
Usage Guidelines
This command is restricted to tunnel interfaces, virtual templates, and crypto maps. The qospre-classify command is unavailable on all other interface types.
You can enable the qospre-classify command for IP packets only.
Note
QoS preclassification is not supported for all fragmented packets. If a packet is fragmented, each fragment might receive different preclassifications.
Examples
The following example enables the QoS for Virtual Private Networks (VPNs) feature on tunnel interfaces and virtual templates:
Router(config-if)# qos pre-classify
Related Commands
Command
Description
showinterfaces
Displays statistics for the interfaces configured on a router or access server.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
qos shape-timer
To specify the Hierarchical Queuing Framework (HQF) shaper-timer interval, use the
qosshape-timer command in global configuration mode. To remove the shaper-timer interval setting, and restore the default value, use the
no form of this command.
qos
shape-timer
{ 1ms | 4ms }
no qos
shape-timer
{ 1ms | 4ms }
Syntax Description
1ms
Sets the HQF shaper timer to 1 millisecond (ms).
4ms
Sets the HQF shaper timer to the default value of 4 ms.
Command Default
The shaper-timer interval is 4-milliseconds.
Command Modes
Global configuration (config)
Command History
Release
Modification
15.1(4)M5
This command was introduced.
Usage Guidelines
By default, the shaper timer uses an interval of 4 ms; however, on high-speed interfaces this setting can lead to a burst at the line rate every 4 ms until the token bucket is exhausted. If there is a low-end device immediately downstream, then packets can be dropped during every burst. To eliminate the unwanted burst behavior, you can reduce the token bucket replenish time from 4 ms to 1 ms using the
qosshape-timer command.
To configure the shape-timer interval, first you use
qosshape-timer command to set the shaper-timer interval, then you create a QoS service policy that specifies the average shape rate, and finally you apply that policy to an interface. Once the policy has been applied to an interface, the interval that the shaper uses to replenish the token bucket is decided by the parameter you specified using the
qosshape-timer command.
Note
The
qosshape-timer command is available on all Integrated Services Routers (ISRs) that do not have a hardware assisted timer.
Examples
The following example shows how to create and attach a service policy to an interface and set the shaper-timer interval to 1 ms:
Specifies the name of the class whose policy you want to create or change, or specifies the default class.
policy-map
Specifies the name of the service policy to configure.
service-policy
Specifies the name of the service policy to be attached to the interface.
shape
Specifies average or peak rate traffic shaping.
queue-depth
To configure the number of incoming packets that the Open Shortest Path First (OSPF) process can keep in its queue, use the
queue-depth command in router configuration mode. To set the queue depth to its default value, use the
no form of the command.
Specifies the queue depth of the OSPF hello process.
update
Specifies the queue depth of the OSPF router process queue.
queue-size
Maximum number of packets in the queue. The range is 1 to 2147483647.
unlimited
Specifies an infinite queue depth.
Command Default
If you do not set a queue size, the OSPF hello process queue depth is unlimited and the OSPF router process (update) queue depth is 200 packets.
Command Modes
Router configuration (config-router)
Command History
Release
Modification
12.2(25)S
This command was introduced.
Usage Guidelines
All incoming OSPF packets are initially enqueued in the hello queue. OSPF hello packets are processed directly from this queue, while all other OSPF packet types are subsequently enqueued in the update queue.
If you configure a router with many neighbors and a large database, use the
queue-depth command to adjust the size of the hello and router queues. Otherwise, packets might be dropped because of queue limits, and OSPF adjacencies may be lost.
Examples
The following example shows how to configure the OSPF update queue to 1500 packets:
Router> enable
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)# router ospf 1
Router(config-router)# queue-depth update 1500
Related Commands
Command
Description
queue-limit
Specifies or modifies the queue limit (size) for a class in bytes, milliseconds (ms), or packets.
queue-listqueuelimit
Designates the queue length limit for a queue.
queue-limit
To specify or
modify the queue limit (size) for a class in bytes, milliseconds (ms),
microseconds (us) or packets, use the
queue-limit
command in QoS policy-map class configuration mode. To remove the queue limit
from a class, use the
no form of this
command.
queue-limitqueue-limit-size
[ bytes | ms | us | packets ]
noqueue-limit
Cisco ASR 1000 Series
Router
queue-limitqueue-limit-size
[ bytes | packets ]
noqueue-limit
Cisco 7600 Series
Routers
queue-limitqueue-limit-size [packets]
noqueue-limit
Syntax Description
queue-limit-size
The
maximum size of the queue. The maximum varies according to the optional unit of
measure keyword specified (bytes,
ms,
us, or
packets).
Note
If an
optional unit of measure is not specified, the default unit of measure depends
on the platform.
Note
For
Cisco ASR 1000 Aggregation Services Routers, bytes is the preferred mode.
bytes
(Optional) Indicates that the unit of measure is bytes. Valid range for bytes
is a number from 1 to 8192000.
Note
The
bytes keyword
is not supported on Cisco 7600 series routers.
Note
For
Cisco ASR 1000 Series Routers, the valid range for bytes is a number from 1 to
64000000.
ms
(Optional) Indicates that the unit of measure is milliseconds. Valid range for
milliseconds is a number from 1 to 3400.
Note
The
ms keyword is
not supported on Cisco 7600 and Cisco ASR 1000 Series Routers.
us
(Optional)
Indicates that the unit of measure is microseconds. Valid range for
microseconds is a number from 1 to 512000.
packets
(Optional) Indicates that the unit of measure is packets. Valid range for
packets is a number from 1 to 32768 but can also vary by platform and release
as follows:
For
ESR-PRE1—The queue size limit for packets is a number from 32 to 16384; the
number must be a power of 2. If the number that you specify is not a power of
2, the device converts the number to the nearest power of 2.
For
Cisco IOS Release 12.2(15)BX and later releases—The queue size limit for
packets is a number from 32 to 16384. The number need not be a power of 2.
For
Cisco IOS Release 12.2(31)SB2 and later releases—The queue size limit for
packets is a number from 16 to 32767.
For
Cisco IOS Release 12.3(7)XI and later releases—If the interface has less than
500 MB of memory, the queue size limit for packets is a number from 8 to 4096;
the number must be a power of 2. If the interface has more than 500 MB of
memory, the queue size limit for packets is a number from 128 to 64000 and must
be a power of 2; if it is not, the device converts the number to the nearest
power of 2.
For
Cisco IOS XE Release 2.1 and later releases—The queue size limit for packets is
a number from 1 to 8192000.
Command Default
The default
behavior of the
queue-limit
command for class queues with and without Weighted Random Early Detection
(WRED) is as follows:
Class queues
with WRED—The device uses the default queue limit of two times the largest WRED
maximum threshold value, rounded to the nearest power of 2.
Note
For Cisco
IOS Release 12.2(16)BX, the device does not round the value to the nearest
power of 2.
Priority
queues and class queues without WRED—The device has buffers for up to 50 ms of
256-byte packets at line rate, but not fewer than 32 packets.
Command Modes
QoS policy-map class configuration (config-pmap-c)
Command History
Release
Modification
12.0(5)T
This
command was introduced.
12.0(5)XE
This
command was integrated into Cisco IOS Release 12.0(5)XE. Support for
VIP-enabled Cisco 7500 Series Routers was added.
12.0(17)SL
This
command was implemented on the Cisco 10000 Aggregation Series Router.
12.1(5)T
This
command was implemented on the VIP-enabled Cisco 7500 Series Routers.
12.2(16)BX
This
command was implemented on the ESR-PRE2.
12.2(28)SB
This
command was integrated into Cisco IOS Release 12.2(28)SB.
12.2(33)SRA
This
command was integrated into Cisco IOS Release 12.2(33)SRA.
12.3(7)XI
This
command was integrated into Cisco IOS Release 12.3(7)XI.
12.2SX
This
command is supported in the Cisco IOS Release 12.2SX train. Support in a
specific 12.2SX release of this train depends on your feature set, platform,
and platform hardware.
12.4(20)T
The
following argument and keyword combinations were added:
queue-limit-sizebytes
queue-limit-sizems
queue-limit-sizepackets
Note
The
bytes keyword
is not supported on Cisco 7600 Series Routers, and the
ms keyword is
not supported on Cisco 7600 and Cisco ASR 1000 Series Routers.
Cisco
IOS XE Release 2.1
This
command was implemented on Cisco ASR 1000 Series Routers.
15.0(1)S1
This
command was modified to improve the qlimit and min/max threshold calculation.
15.0(1)M5
This
command was modified. Hierarchical Queueing Framework (HQF) capability was
improved.
15.2(2)T
This
command was modified. The
us keyword
was added. The default unit of measure changed from packets to a
platform-dependent unit.
15.4(1)S
This command was implemented on the Cisco ASR 901 series
routers.
Usage Guidelines
Weighted Fair
Queueing
Weighted fair
queueing (WFQ) creates a queue for every class for which a class map is
defined. Packets that satisfy the match criterion for a class accumulate in the
queue reserved for the class until they are sent, which occurs when the queue
is serviced by the fair queueing process. When the maximum packet threshold
that you defined for the class is reached, enqueueing of any further packets to
the class queue causes tail drop or, if WRED is configured for the class
policy, packet drop to take effect.
Changes in
Cisco IOS Release 15.0(1)S1
Prior to Cisco
IOS Release 15.0(1)S1, if no queue limit was configured, the queue limit for
the current class was based on the parent values for available buffers and
current class allocated bandwidth. In the implicit WRED min/max scenario,
thresholds were calculated from the available buffers.
Thresholds were
calculated from the available aggregate queue limit for each class. The WRED
min/max threshold values would not be adjusted if there was a user-defined
queue-limit configuration. The min/max threshold would still be derived from
the “visible_bw” value seen by this traffic class. The WRED functionality could
fail because of this inconsistent qlimit and min/max threshold calculation.
Beginning in
Cisco IOS Release 15.0(1)S1, the queue limit is always calculated from the
parent queue limit and allocated bandwidth in the current class. When you use
the
queue-limit
command to explicitly configure the values, these values are used as the
definition of the queue limit.
To ensure optimum
functionality, use the
queue-limit
command to configure the proper min/max threshold for each WRED class based on
the queue-limit configuration.
Changes in
Cisco IOS Release 15.2(2)T
Prior to Cisco IOS
Release 15.2(2)T, if the optional unit of measure was not specified, the unit
of measure used was packets. Beginning in Cisco IOS Release 15.2(2)T, if the
optional unit of measure is not specified, the unit used depends on the
platform.
Overriding
Queue Limits Set by the bandwidth Command
Use the
bandwidth
command with the modular quality of service (QoS) CLI) (MQC) to specify the
bandwidth for a particular class. When used with MQC, the
bandwidth
command has a default queue limit for the class. This queue limit can be
modified using the
queue-limit
command, thereby overriding the default set by the
bandwidth
command.
Note
Using the
queue-limit
command to modify the default queue limit is especially important for
higher-speed interfaces, in order to meet the minimum bandwidth guarantees
required by the interface.
Prior to the
deployment of the Hierarchical Queueing Framework (HQF), the default maximum
queue limit on a subinterface was 512 if no hold queue was configured on the
main interface.
As part of HQF,
this restriction was removed beginning in Cisco IOS Release 15.0(1)M5. Now the
maximum queue limit can be set as high as the hold-queue size on the main
interface.
If no hold queue
is configured on the main interface, the aggregate queue limit can go up to
1000. If the hold-queue is explicitly configured on the main interface, then
the aggregate queue limit can go up to the hold-queue value. There is no limit
per subinterface.
The maximum
configurable hold-queue value of 4096 was increased to 240,000 for users who
want to configure higher aggregate queue-limit values. However, configuring
high queue-limit and hold-queue values is not recommended.
Examples
The following
example configures a policy map called policy11. The policy11 policy map
contains a class called acl203. The policy map for this class is configured so
that the queue reserved for the class has a maximum queue size of 40 packets.
Specifies the maximum aggregate bandwidth for H.323 traffic and verifies the
available bandwidth of the destination gatekeeper.
class(policy-map)
Specifies the name of the class whose policy you want to create or change and
the default class (commonly known as the class-default class) before you
configure its policy.
classclass-default
Specifies the default traffic class whose bandwidth is to be configured or
modified.
policy-map
Creates
or modifies a policy map that can be attached to one or more interfaces to
specify a service policy.
qos default
queue-limit
Configures the default queue limit for all QoS-based classes on
a device in bytes, milliseconds (ms), microseconds (us), or packets.
queue-limit atm clp
To specify the maximum size (in cells, microseconds, or milliseconds) of a queue for a specific traffic class, use the queue-limitatmclp command in policy-map class configuration mode. To remove the queue limit atm cell loss priority (clp) value from a class, use the no form of this command.
queue-limitatmclpqueue-size
{ cells | ms | us }
noqueue-limitatmclp
Syntax Description
queue-size
Threshold value. The range is 1-262144.
cells | ms | us
Unit of measure for the queue size; ms = milliseconds; us = microseconds.
Command Default
No default behavior or values
Command Modes
Policy-map class configuration (config-pmap-c)
Command History
Release
Modification
12.0(30)S
This command was introduced.
Usage Guidelines
You can use the queue-limitatmclpcommand only with other queuing features, such as weighted fair queuing (WFQ). WFQ creates a queue for every class for which you define a class map. You can apply the policy map that you created with the atm clp based queue-limit command only to ATM interfaces on Cisco 12000 Series Routers.
Use the queue-limitatmclp command only after you have issued the queue-limitcommand using the same traffic class.
Use the noqueue-limit command to remove both the global queue-limit queue-size value and the queue-limit atm clp queue-size value if you configured it.
Packets satisfying the match criteria for a class accumulate in the queue reserved for the class until they are sent, which occurs when the queue is serviced by the weighted fair queuing process. When the defined maximum packet threshold for the class is reached, enqueuing of additional packets to the class queue causes tail drop.
You can specify the CLP queue-limit threshold in cells, milliseconds (ms), or microseconds (us). However, the unit of measure cannot be mixed. For example, if you specify the CLP queue-limit threshold in milliseconds, then you must also specify the global queue-limit threshold in milliseconds.
Note
When you specify the queue-limit threshold as cells, milliseconds, or microseconds, it is internally converted to cells by using the visible bandwidth that is available to the class or the ATM virtual circuit (VC).
Examples
In the following example, a policy map called “POLICY-ATM” has been configured. The “POLICY-ATM” policy map contains a class called “CLASS-ATM”. The bandwidth for this class is specified as a percentage (20), and the queue-limit command sets the global queue-limit threshold to 1000 cells. The queue-limitatmclp command sets the queue-limit threshold for ATM CLP data to 100 cells:
Specifies or modifies the bandwidth allocated for a class belonging to a policy map.
classclass-default
Specifies the default traffic class whose bandwidth is to be configured or modified.
class(policy-map)
Specifies the name of the class whose policy you want to create or change, and the default class (commonly known as the class-default class) before you configure its policy.
policy-map
Creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy.
queue-limit
Specifies or modifies the maximum number of packets the queue can hold for a class configured in a policy map.
queue-list default
To assign a priority
queue for those packets that do not match any other rule in the queue list, use the queue-listdefault command in global configuration mode. To restore the default value, use the noform of this command.
queue-listlist-numberdefaultqueue-number
noqueue-listlist-numberdefaultqueue-number
Syntax Description
list-number
Number of the queue list. Any number from 1 to 16 that identifies the queue list.
queue-number
Number of the queue. Any number from 1 to 16.
Command Default
Disabled
The default number of the queue list is queue number 1.
Command Modes
Global configuration
Command History
Release
Modification
10.0
This command was introduced.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
Usage Guidelines
When you use multiple rules, remember that the system reads the queue-list commands in order of appearance. When classifying a packet, the system searches the list of rules specified by queue-list commands for a matching protocol or interface type. When a match is found, the system assigns the packet to the appropriate queue. The system searches the list in the order specified, and the first matching rule terminates the search.
Queue number 0 is a system queue. It is emptied before any of the other queues are processed. The system enqueues high-priority packets, such as keepalives, to this queue.
Use theshowinterfaces command to display the current status of the output queues.
Examples
In the following example, the default queue for list 10 is set to queue number 2:
queue-list 10 default 2
Related Commands
Command
Description
custom-queue-list
Assigns a custom queue list to an interface.
queue-listinterface
Establishes queueing priorities on packets entering on an interface.
queue-listprotocol
Establishes queueing priority based on the protocol type.
queue-listqueuebyte-count
Specifies how many bytes the system allows to be delivered from a given queue during a particular cycle.
queue-listqueuelimit
Designates the queue length limit for a queue.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueueing
Lists all or selected configured queueing strategies.
queue-list interface
To establish queueing priorities on packets entering on an interface, use thequeue-listinterface command in global configuration mode. To remove an entry from the list, use the
no form of this command.
Number of the queue list. Any number from 1 to 16 that identifies the queue list.
interface-type
Type of the interface.
interface-number
Number of the interface.
queue-number
Number of the queue. Any number from 1 to 16.
Command Default
No queueing priorities are established.
Command Modes
Global configuration
Command History
Release
Modification
10.0
This command was introduced.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
Usage Guidelines
When you use multiple rules, remember that the system reads the
queue-list commands in order of appearance. When classifying a packet, the system searches the list of rules specified by
queue-list commands for a matching protocol or interface type. When a match is found, the system assigns the packet to the appropriate queue. The list is searched in the order specified, and the first matching rule terminates the search.
Examples
In the following example, queue list 4 establishes queueing priorities for packets entering on interface tunnel 3. The queue number assigned is 10.
queue-list 4 interface tunnel 3 10
Related Commands
Command
Description
custom-queue-list
Assigns a custom queue list to an interface.
queue-listdefault
Assigns a priority queue for those packets that do not match any other rule in the queue list.
queue-listprotocol
Establishes queueing priority based on the protocol type.
queue-listqueuebyte-count
Specifies how many bytes the system allows to be delivered from a given queue during a particular cycle.
queue-listqueue
limit
Designates the queue length limit for a queue.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueueing
Lists all or selected configured queueing strategies.
queue-list lowest-custom
To set the lowest number for a queue to be treated as a custom queue, use the
queue-listlowest-customcommand in global configuration mode. To restore the default value, use the
noform of this command.
queue-listlist-numberlowest-customqueue-number
noqueue-listlist-numberlowest-customqueue-number
Syntax Description
list-number
Number of the queue list. Any number from 1 to 16 that identifies the queue list.
queue-number
Number of the queue. Any number from 1 to 16.
Command Default
The default number of the lowest custom queue is 1.
Command Modes
Global configuration
Command History
Release
Modification
11.0
This command was introduced.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
Usage Guidelines
All queues from queue 0 to the queue prior to the one specified in the
queue-listlowest-custom command use the priority queue. (Queue 0 has the highest priority.)
All queues from the one specified in the
queue-listlowest-custom command to queue 16 use a round-robin scheduler.
Use theshowqueueingcustomcommand to display the current custom queue configuration.
Examples
In the following example, the lowest custom value is set to 2 for queue list 4:
queue-list 4 lowest-custom 2
Related Commands
Command
Description
custom-queue-list
Assigns a custom queue list to an interface.
queue-listinterface
Establishes queueing priorities on packets entering on an interface.
queue-listprotocol
Establishes queueing priority based on the protocol type.
queue-listqueue byte-count
Specifies how many bytes the system allows to be delivered from a given queue during a particular cycle.
queue-listqueuelimit
Designates the queue length limit for a queue.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueueing
Lists all or selected configured queueing strategies.
queue-list protocol
To establish
queueing priority based upon the protocol type, use the queue-listprotocol command in global configuration mode. To remove an entry from the list, use the noform of this command.
Possible keywords are fragments,gt,list,lt,tcp, and udp. See the priority-listprotocol command for more information about this keyword.
Command Default
No queueing priorities are established.
Command Modes
Global configuration
Command History
Release
Modification
10.0
This command was introduced.
12.2(13)T
This command was modified to remove apollo, vines, and xns from the list of protocol types. These protocols were removed because Apollo Domain, Banyan VINES, and Xerox Network Systems (XNS) were removed in Release 12.2(13)T.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
Usage Guidelines
When you use multiple rules for a single protocol, remember that the system reads the queue-list commands in order of appearance. When classifying a packet, the system searches the list of rules specified by queue-list commands for a matching protocol. When a match is found, the system assigns the packet to the appropriate queue. The system searches the list in the order specified, and the first matching rule terminates the search.
The decnet_router-l1 keyword refers to the multicast address for all level 1 routers, which are intra-area routers, and the decnet_router-l2 keyword refers to all level 2 routers, which are interarea routers.
The dlsw,rsrb, and stunkeywords refer only to direct encapsulation.
Use the tables listed in the priority-listprotocol command documention to configure the queueing priorities for your system.
Examples
The following example assigns 1 as the custom queue list, specifies DECnet as the protocol type, and assigns 3 as a queue number to the packets sent on this interface:
queue-list 1 protocol decnet 3
The following example assigns DECnet packets with a size greater than 200 bytes to queue number 2:
queue-list 2 protocol decnet 2 gt 200
The following example assigns DECnet packets with a size less than 200 bytes to queue number 2:
queue-list 4 protocol decnet 2 lt 200
The following example assigns traffic that matches IP access list 10 to queue number 1:
queue-list 1 protocol ip 1 list 10
The following example assigns Telnet packets to queue number 2:
queue-list 4 protocol ip 2 tcp 23
The following example assigns User Datagram Protocol (UDP) Domain Name Service packets to queue number 2:
queue-list 4 protocol ip 2 udp 53
The following example assigns traffic that matches Ethernet type code access list 201 to queue number 1:
queue-list 1 protocol bridge 1 list 201
Related Commands
Command
Description
custom-queue-list
Assigns a custom queue list to an interface.
queue-listdefault
Assigns a priority queue for those packets that do not match any other rule in the queue list.
queue-listqueuebyte-count
Specifies how many bytes the system allows to be delivered from a given queue during a particular cycle.
queue-listqueuelimit
Designates the queue length limit for a queue.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueueing
Lists all or selected configured queueing strategies.
queue-list queue byte-count
To specify how many bytes the system allows to be delivered from a given queue during a particular cycle
, use the queue-listqueuebyte-count command in global configuration mode. To return the byte count to the default value, use the no form of this command.
Number of the queue list. Any number from 1 to 16.
queue-number
Number of the queue. Any number from 1 to 16.
byte-count-number
The average number of bytes the system allows to be delivered from a given queue during a particular cycle.
Command Default
This command is disabled by default. The default byte count is 1500 bytes.
Command Modes
Global configuration
Command History
Release
Modification
10.0
This command was introduced.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
Examples
In the following example, queue list 9 establishes the byte count as 1400 for queue number 10:
queue-list 9 queue 10 byte-count 1400
Related Commands
Command
Description
custom-queue-list
Assigns a custom queue list to an interface.
queue-listdefault
Assigns a priority queue for those packets that do not match any other rule in the queue list.
queue-listinterface
Establishes queueing priorities on packets entering on an interface.
queue-listprotocol
Establishes queueing priority based on the protocol type.
queue-listqueuebyte-count
Specifies how many bytes the system allows to be delivered from a given queue during a particular cycle.
queue-listqueuelimit
Designates the queue length limit for a queue.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueueing
Lists all or selected configured queueing strategies.
queue-list queue limit
To designate the
queue length limit for a queue, use the queue-listqueuelimit command in global configuration mode. To return the queue length to the default value, use the no form of this command.
Number of the queue list. Any number from 1 to 16.
queue-number
Number of the queue. Any number from 1 to 16.
limit-number
Maximum number of packets that can be enqueued at any time. The range is from 0 to 32767 queue entries. A value of 0 means that the queue can be of unlimited size.
Command Default
The default queue length limit is 20 entries.
Command Modes
Global configuration
Command History
Release
Modification
10.0
This command was introduced.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
Examples
In the following example, the queue length of queue 10 is increased to 40:
queue-list 5 queue 10 limit 40
Related Commands
Command
Description
custom-queue-list
Assigns a custom queue list to an interface.
queue-listdefault
Assigns a priority queue for those packets that do not match any other rule in the queue list.
queue-listinterface
Establishes queueing priorities on packets entering on an interface.
queue-listprotocol
Establishes queueing priority based on the protocol type.
queue-listqueuebyte-count
Specifies how many bytes the system allows to be delivered from a given queue during a particular cycle.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueueing
Lists all or selected configured queueing strategies.
random-detect
Note
Effective with Cisco IOS Release 15.0(1)S and Cisco IOS Release 15.1(3)T, the
random-detect command is hidden in interface configuration mode. Although this command is still available in Cisco IOS software, the CLI interactive Help does not display it if you enter a question mark at the command line. This command will be completely removed from interface configuration mode in a future release, which means that you will need to use the appropriate replacement command (or sequence of commands). For more information (including a list of replacement commands), see the "Legacy QoS Command Deprecation" feature document in the
Cisco IOS Quality of Service Solutions Configuration Guide.
To enable Weighted Random Early Detection (WRED) or distributed WRED (dWRED) on an interface, use the
random-detect command in interface configuration mode. To configure WRED for a class in a policy map, use the
random-detect command in QoS policy-map class configuration mode. To disable WRED or dWRED, use the
no form of this command.
random-detect
[ dscp-based | prec-based ]
norandom-detect
Syntax Description
dscp-based
(Optional) Specifies that WRED is to use the differentiated services code point (DSCP) value when it calculates the drop probability for a packet.
prec-based
(Optional) Specifies that WRED is to use the IP Precedence value when it calculates the drop probability for a packet.
Command Default
WRED and dWRED are disabled by default.
Command Modes
Interface configuration (config-if)
QoS policy-map class configuration (config-pmap-c)
Command History
Release
Modification
11.1CC
This command was introduced.
12.1(5)T
This command was integrated into Cisco IOS Release 12.1(5)T. Arguments were added to support Differentiated Services (DiffServ) and Assured Forwarding (AF) Per Hop Behavior (PHB).
12.1(5a)E
This command was integrated into Cisco IOS Release 12.1(5a)E in policy map class configuration mode only. This command was implemented on Versatile Interface Processor (VIP)-enabled Cisco 7500 series routers and Catalyst 6000 family switches with a FlexWAN module.
12.0(15)S
This command was integrated into Cisco IOS Release 12.0(15)S in QoS policy-map class configuration mode only.
12.2(14)S
This command was integrated into Cisco IOS Release 12.2(14)S.
12.0(28)S
This command was integrated into Cisco IOS Release 12.0(28)S in QoS policy map class configuration mode.
12.2(28)SB
This command was integrated into Cisco IOS Release 12.2(28)SB in QoS policy map class configuration mode.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
12.4(20)T
Support was added for hierarchical queueing framework (HQF) using the modular quality of service (QoS) CLI (MQC).
15.0(1)S
This command was modified. This command was hidden in interface configuration mode.
15.1(3)T
This command was modified. This command was hidden in interface configuration mode.
Cisco IOS XE 3.6S
This command was modified. Support was added for the Cisco ASR 903 router.
Usage Guidelines
Keywords
If you choose not to use either the
dscp-based or the
prec-based keyword, WRED uses the IP Precedence value (the default method) to calculate the drop probability for the packet.
Availability
The
random-detect command is not available at the interface level for Cisco IOS Releases 12.1E or 12.0S. The
random-detect
command is available in policy-map class configuration mode only for Cisco IOS Releases 12.1E, 12.0S, and later releases.
WRED Functionality
WRED is a congestion avoidance mechanism that slows traffic by randomly dropping packets when congestion exists. dWRED is similar to WRED but uses the Versatile Interface Processor (VIP) instead of the Route Switch Processor (RSP). WRED and dWRED are most useful with protocols such as Transport Control Protocol (TCP) that respond to dropped packets by decreasing the transmission rate.
The router automatically determines parameters to use in the WRED calculations. To change these parameters, use the
random-detectprecedence command.
Platform Support for dWRED
The dWRED feature is supported only on Cisco 7000 series routers with an RSP7000 card and Cisco 7500 series routers with a VIP2-40 or higher interface processor. A VIP2-50 interface processor is strongly recommended when the aggregate line rate of the port adapters on the VIP is greater than DS3. A VIP2-50 interface processor is required for OC-3 rates.
To use dWRED, distributed Cisco Express Forwarding switching must first be enabled on the interface. For more information on distributed Cisco Express Forwarding, refer to the
Cisco IOS Switching Services Configuration Guide and the
Cisco IOS Switching Services Command Reference .
WRED in a Policy Map
You can configure WRED as part of the policy map for a standard class or the default class. The WRED
random-detect command and the weighted fair queueing (WFQ)
queue-limit command are mutually exclusive. If you configure WRED, its packet drop capability is used to manage the queue when packets exceeding the configured maximum count are enqueued. If you configure the WFQ
queue-limit command, tail drop is used.
To configure a policy map and create class policies, use the
policy-map and
class (policy-map) commands. When creating a class within a policy map, you can use the
random-detect command with either of the following commands:
bandwidth (policy-map class)
fair-queue (class-default)--for the default class only
Note
If you use WRED packet drop instead of tail drop for one or more classes in a policy map, you must ensure that WRED is not configured on the interface to which you attach that policy map.
Note
dWRED is not supported for classes in a policy map.
Two Methods for Calculating the Drop Probability of a Packet
This command includes two optional keywords,
dscp-based andprec-based, that determine the method WRED uses to calculate the drop probability of a packet.
Note the following points when deciding which method to instruct WRED to use:
With the
dscp-based keyword, WRED uses the DSCP value (that is, the first six bits of the IP type of service (ToS) byte) to calculate the drop probability.
With the
prec-based keyword, WRED will use the IP Precedence value to calculate the drop probability.
The
dscp-based and
prec-based keywords are mutually exclusive.
If neither argument is specified, WRED uses the IP Precedence value to calculate the drop probability (the default method).
Examples
The following example configures WRED on the High-Speed Serial Interface (HSSI) 0/0/0 interface:
interface Hssi0/0/0
random-detect
The following example configures the policy map called policy1 to contain policy specification for the class called class1. During times of congestion, WRED packet drop is used instead of tail drop.
! The following commands create the class map called class1:
class-map class1
match input-interface fastethernet0/1
! The following commands define policy1 to contain policy specification for class1:
policy-map policy1
class class1
bandwidth 1000
random-detect
The following example enables WRED to use the DSCP value 8. The minimum threshold for the DSCP value 8 is 24 and the maximum threshold is 40. This configuration was performed at the interface level.
The following example enables WRED to use the DSCP value 8 for class c1. The minimum threshold for DSCP value 8 is 24 and the maximum threshold is 40. The last line attaches the service policy to the output interface or virtual circuit (VC) p1.
Specifies or modifies the bandwidth allocated for a class belonging to a policy map or enables ATM overhead accounting.
class
Specifies the name of the class whose policy you want to create or change or specifies the default class (commonly known as the class-default class) before configuring its policy.
fair-queue
Specifies the number of dynamic queues to be reserved for use by the class-default class as part of the default class policy.
policy-map
Creates a policy map that defines a Control Plane Policing and Protection (CoPP) per-user policy.
queue-limit
Specifies or modifies the queue limit (size) for a class in bytes, milliseconds (ms), microseconds (us) or packets.
random-detectdscp
Changes the minimum and maximum packet thresholds for the DSCP value.
random-detectexponential-weighting-constant
Configures the WRED and dWRED exponential weight factor for the average queue size calculation.
random-detectflow
Enables flow-based WRED.
random-detectprecedence
Configures WRED and dWRED parameters for a particular IP Precedence.
showinterfaces
Displays statistics for all interfaces configured on the router or access server.
showqueueing
Lists all or selected configured queueing strategies.
showtech-supportrsvp
Generates a report of all RSVP-related information.
random-detect (per VC)
Note
Effective with Cisco IOS Release 15.1(3)T, the
random-detect(per VC) command is hidden. Although this command is still available in Cisco IOS software, the CLI interactive Help does not display it if you attempt to view it by entering a question mark at the command line. This command will be completely removed in a future release. For more information, see the "Legacy QoS Command Deprecation" feature document in the
Cisco IOS Quality of Service Solutions Configuration Guide.
To enable per-virtual circuit (VC) Weighted Random Early Detection ( WRED) or per-VC VIP-distributed WRED ( DWRED), use the
random-detectcommand in VC submode mode. To disable per-VC WRED and per-VC DWRED, use the
no form of this command.
random-detect
[ attachgroup-name ]
norandom-detect
[ attachgroup-name ]
Syntax Description
attachgroup-name
(Optional) Name of the WRED or DWRED group.
Command Default
WRED and DWRED are disabled by default.
Command Modes
VC submode
Command History
Release
Modification
12.0(3)T
This command was introduced.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
15.1(3)T
This command was modified. This command was hidden.
Usage Guidelines
WRED is a congestion avoidance mechanism that slows traffic by randomly dropping packets when congestion exists. DWRED is similar to WRED but uses the Versatile Interface Processor (VIP) instead of the Route Switch Processor (RSP). WRED and DWRED are most useful with protocols like TCP that respond to dropped packets by decreasing the transmission rate.
WRED and DWRED are configurable at the interface and per-VC levels. The VC-level WRED or DWRED configuration will override the interface-level configuration if WRED or DWRED is also configured at the interface level.
Use this command to configure a single ATM VC or a VC that is a member of a bundle.
Note the following points when using the
random-detect(per VC) command:
If you use this command without the optional
attach keyword, default WRED or DWRED parameters (such as minimum and maximum thresholds) are used.
If you use this command with the optional
attach keyword, the parameters defined by the specified WRED or DWRED parameter group are used. (WRED or DWRED parameter groups are defined through the
random-detect-group command.) If the specified WRED or DWRED group does not exist, the VC is configured with default WRED or DWRED parameters.
When this command is used to configure an interface-level WRED or DWRED group to include per-VC WRED or DWRED as a drop policy, the configured WRED or DWRED group parameters are inherited under the following conditions:
All existing VCs--including Resource Reservation Protocol (RSVP) switched virtual circuits (SVCs) that are not specifically configured with a VC-level WRED or DWRED group--will inherit the interface-level WRED or DWRED group parameters.
Except for the VC used for signalling and the Interim Local Management Interface (ILMI) VC, any VCs created after the configuration of an interface-level DWRED group will inherit the parameters.
When an interface-level WRED or DWRED group configuration is removed, per-VC WRED or DWRED parameters are removed from any VC that inherited them from the configured interface-level WRED or DWRED group.
When an interface-level WRED or DWRED group configuration is modified, per-VC WRED or DWRED parameters are modified accordingly if the WRED or DWRED parameters were inherited from the configured interface-level WRED or DWRED group configuration.
This command is only supported on interfaces that are capable of VC-level queueing. The only currently supported interface is the Enhanced ATM port adapter (PA-A3).
The DWRED feature is only supported on Cisco 7000 series routers with an RSP7000 card and Cisco 7500 series routers with a VIP2-40 or greater interface processor. A VIP2-50 interface processor is strongly recommended when the aggregate line rate of the port adapters on the VIP is greater than DS3. A VIP2-50 interface processor is required for OC-3 rates.
To use DWRED, distributed Cisco Express Forwarding (dCEF) switching must first be enabled on the interface. For more information on dCEF, refer to the Cisco IOS Switching Services Configuration Guide and the Cisco IOS Switching Services Command Reference.
Examples
The following example configures per-VC WRED for the permanent virtual circuit (PVC) called cisco. Because the
attach keyword was not used, WRED uses default parameters.
pvc cisco 46
random-detect
The following example creates a DWRED group called Rome and then applies the parameter group to an ATM PVC:
! The following commands create the DWRED parameter group Rome:
random-detect-group Rome
precedence rsvp 46 50 10
precedence 1 32 50 10
precedence 2 34 50 10
precedence 3 36 50 10
precedence 4 38 50 10
precedence 5 40 50 10
precedence 6 42 50 10
precedence 7 44 50 10
exit
exit
! The following commands create a PVC on an ATM interface and then apply the
! DWRED group Rome to that PVC:
interface ATM2/0.23 point-to-point
ip address 10.9.23.10 255.255.255.0
no ip mroute-cache
pvc vc1 201/201
random-detect attach Rome
vbr-nrt 2000 1000 200
encapsulation aal5snap
The following
showqueueing command displays the current settings for each of the IP Precedences following configuration of per-VC DWRED:
Specifies the name of the class whose policy you want to create or change, and the default class (commonly known as the class-default class) before you configure its policy.
random-detectexponential-weighting-constant
Configures the WRED and DWRED exponential weight factor for the average queue size calculation.
random-detect-group
Defines the WRED or DWRED parameter group.
random-detectprecedence
Configures WRED and DWRED parameters for a particular IP Precedence.
showinterfaces
Displays the statistical information specific to a serial interface.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueueing
Lists all or selected configured queueing strategies.
random-detect aggregate
To enable aggregate Weighted Random Early Detection (WRED), use the
random-detectaggregatecommand in policy-map class configuration mode. To disable aggregate WRED, use the
no form of this command.
(Optional) Enables aggregate WRED based on IP precedence values. This is the default.
dscp-based
(Optional) Enables aggregate WRED based on differentiated services code point (DSCP) values.
minimum-threshmin-thresh
(Optional) Default minimum threshold (in number of packets) to be used for all subclasses (IP precedence or DSCP values) that have not been specifically configured. Valid values are from 1 to 12288.
maximum-threshmax-thresh
(Optional) Default maximum threshold (in number of packets) to be used for all subclasses (IP precedence or DSCP values) that have not been specifically configured. Valid values are from the minimum threshold argument to 12288.
mark-probabilitymark-prob
(Optional) Default denominator for the fraction of packets dropped when the average queue depth is at the maximum threshold. This value is used for all subclasses (IP precedence or DSCP values) that have not been specifically configured. Valid values are from 1 to 255.
Command Default
If no
precedence-based or
dscp-basedkeyword is specified in the command, the default is
precedence-based.
If optional parameters for a default aggregate class are not defined, all subclass values that are not explicitly configured will use plain (non-weighted) RED drop behavior. This is different from standard random-detect configuration where the default is to always use WRED behavior.
Command Modes
Policy-map class configuration
Command History
Release
Modification
12.2(18)SXE
This command was introduced.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2(31)SB2
This command was integrated into Cisco IOS Release 12.2(31)SB2 on the Cisco 10000 series router for the PRE3.
Usage Guidelines
For ATM interfaces, the Aggregate WRED feature requires that the ATM SPA cards are installed in a Cisco 7600 SIP-200 carrier card or a Cisco 7600 SIP-400 carrier card.
To configure WRED on an ATM interface, you must use the random-detect aggregate commands; the standard random-detect commands are no longer supported on ATM interfaces.
The
precedence-based and
dscp-based keywords are mutually exclusive. If you do not specify either keyword,
precedence-based is the default.
Defining WRED profile parameter values for the default aggregate class is optional. If defined, WRED profile parameters applied to the default aggregate class will be used for all subclasses that have not been explicitly configured. If all possible IP precedence or DSCP values are defined as subclasses, a default specification is unnecessary. If the optional parameters for a default aggregate class are not defined and packets with an unconfigured IP precedence or DSCP value arrive at the interface, plain (non-weighted) RED drop behavior will be used.
Use this command with a
random-detectprecedence(aggregate) or
random-detectdscp(aggregate) command within a policy map configuration to configure aggregate Weighted Random Early Detection (WRED) parameters for specific IP precedence or DSCP value(s).
After the policy map is defined, the policy map must be attached at the VC level.
Use the
showpolicy-mapinterface command to display the statistics for aggregated subclasses.
Examples
The following example shows a precedence-based aggregate WRED configuration for an ATM interface. Note that first a policy map named prec-aggr-wred is defined for the default class, then precedence-based Aggregate WRED is enabled with the
random-detectaggregate command, then subclasses and WRED parameter values are assigned in a series of
random-detectprecedence(aggregate)commands, and, finally, the policy map is attached at the ATM VC level using the
interfaceand
service-policy commands.
The following example shows a DSCP-based aggregate WRED configuration for an ATM interface. Note that first a policy map named dscp-aggr-wred is defined for the default class, then dscp-based Aggregate WRED is enabled with the
random-detectdscp-basedaggregate command, then subclasses and WRED parameter values are assigned in a series of
random-detectdscp (aggregate) commands, and, finally, the policy map is attached at the ATM VC level using the
interfaceand
service-policy commands.
Specifies the name of the class whose policy you want to create or change, and the default class (commonly known as the class-default class) before you configure its policy.
interface
Configures an interface type and enters interface configuration mode.
policy-map
Creates a policy map that can be attached to one or more interfaces to specify a service policy.
random-detectprecedence(aggregate)
Configures aggregate WRED parameters for specific IP precedence values.
random-detectdscp(aggregate)
Configures aggregate WRED parameters for specific DSCP values.
service-policy
Attaches a policy map to an input interface or VC, or an output interface or VC, to be used as the service policy for that interface or VC.
showpolicy-mapinterface
Displays the configuration of all classes configured for all service policies on the specified interface or displays the classes for the service policy for a specific PVC on the interface.
random-detect atm-clp-based
To enable weighted random early detection (WRED) on the basis of the ATM cell loss priority (CLP) of a packet, use the random-detectatm-clp-based command in policy-map class configuration mode. To disable WRED, use the no form of this command.
Minimum threshold in number of packets. Valid values are 1 to 4096.
max-thresh-value
Maximum threshold in number of packets. Valid values are 1 to 4096.
max-probability-denominator-value
Denominator for the fraction of packets dropped when the average queue depth is at the maximum threshold. Valid values are 1 to 65535.
Command Default
When WRED is configured, the default minimum and maximum thresholdsare determined on the basis of output buffering capacity and the transmission speed for the interface.
The default maximum probability denominator is 10.
On the Cisco 10000 series router, the default is disabled.
Command Modes
Policy-map class configuration (config-pmap-c)
Command History
Release
Modification
12.0(28)S
This command was introduced.
12.2(28)SB
This command was integrated into Cisco IOS Release 12.2(28)SB.
12.2(33)SB
This command was introduced on the PRE3 and PRE4 for the Cisco 10000 series router.
12.4(20)T
Support was added for hierarchical queueing framework (HQF) using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC).
Usage Guidelines
You cannot use the random-detectatm-clp-based command with the random-detectcos-based command in the same HQF configuration. You must use the norandom-detectcos-based command to disable it before you configure the random-detectatm-clp-based command.
Examples
In the following example, WRED is configured on the basis of the ATM CLP. In this configuration, the random-detectatm-clp-basedcommand has been configured and an ATM CLP of 1 has been specified.
Router> enable
Router# configure terminal
Router(config)# policy-map policymap1
Router(config-pmap)# class class1
Router(config-pmap-c)# random-detect atm-clp-based 1
Router(config-pmap-c)#
end
Related Commands
Command
Description
random-detectclp
Specifies the ATM CLP value of a packet, the minimum and maximum thresholds, and the maximum probability denominator used for enabling WRED.
random-detectcos
Specifies the CoS value of a packet, the minimum and maximum thresholds, and the maximum probability denominator used for enabling WRED.
random-detectcos-based
Enables WRED on the basis of the CoS value of a packet.
showpolicy-map
Displays the configuration of all classes for a specified service policy map or all classes for all existing policy maps.
showpolicy-mapinterface
Displays the packet statistics of all classes that are configured for all service policies either on the specified interface or subinterface or on a specific PVC on the interface.
random-detect clp
To specify the ATM cell loss priority (CLP) value of a packet, the minimum and maximum thresholds, and the maximum probability denominator used for enabling weighted random early detection (WRED), use the
random-detectclp command in policy-map class configuration mode. To reset the thresholds and maximum probability denominator to the default values for the specified ATM CLP, use the
no form of this command.
Minimum threshold in number of packets. Valid values are in the range 1 to 512000000.
max-threshold
Maximum threshold in number of packets. Valid values are in the range 1 to 512000000.
max-probability-denominator
Denominator for the fraction of packets dropped when the average queue depth is at the maximum threshold. Valid values are 1 to 65535.
Command Default
The default values for the
min-threshold
and
max-threshold arguments are based on the output buffering capacity and the transmission speed for the interface.
The default for the
max-probability-denominator argument is 10; that is, 1 out of every 10 packets is dropped at the maximum threshold.
Command Modes
Policy-map class configuration (config-pmap-c)
Command History
Release
Modification
12.0(28)S
This command was introduced.
12.2(28)SB
This command was integrated into Cisco IOS Release 12.2(28)SB.
15.2(2)T
This command was modified. The maximum and minimum threshold ranges were changed.
Usage Guidelines
Note the following points when using the
random-detectclp command:
When the average queue length reaches the minimum threshold, WRED randomly drops some packets with the specified IP precedence.
When the average queue length exceeds the maximum threshold, WRED drops all packets with the specified IP precedence.
While the range of values for the
min-threshold
and
max-threshold arguments is from 1 to 512000000, the actual values that you can specify depend on the type of random detect you are configuring. For example, the maximum threshold value cannot exceed the queue limit.
The
max-probability-denominator argument is the fraction of packets dropped when the average queue depth is at the maximum threshold. For example, if the denominator is 512, 1 out of every 512 packets is dropped when the average queue is at the maximum threshold.
Examples
In the following example, WRED has been enabled using the
random-detectclp command. With the
random-detectclp command, the ATM CLP has been specified, along with the minimum and maximum thresholds, and the maximum probability denominator.
Router> enable
Router# configure terminal
Router(config)# policy-map policymap1
Router(config-pmap)# class class1
Router(config-pmap-c)# random-detect clp 1 12 25 1/10
Router(config-pmap-c)# end
Related Commands
Command
Description
random-detectatm-clp-based
Enables WRED on the basis of the ATM CLP of a packet.
random-detectcos
Specifies the CoS value of a packet, the minimum and maximum thresholds, and the maximum probability denominator used for enabling WRED.
random-detectcos-based
Enables WRED on the basis of the CoS value of a packet.
showpolicy-map
Displays the configuration of all classes for a specified service policy map or all classes for all existing policy maps.
showpolicy-mapinterface
Displays the packet statistics of all classes that are configured for all service policies either on the specified interface or subinterface or on a specific PVC on the interface.
random-detect cos-based
To enable weighted random early detection (WRED) on the basis of the class of service (CoS) value of a packet, use the random-detectcos-based command in policy-map class configuration mode. To disable WRED, use the no form of this command.
random-detectcos-basedcos-value
norandom-detectcos-based
Syntax Description
cos-value
Specific IEEE 802.1Q CoS values from 0 to 7.
Command Default
When WRED is configured, the default minimum and maximum thresholds are determined on the basis of output buffering capacity and the transmission speed for the interface.
The default maximum probability denominator is 10.
Command Modes
Policy-map class configuration (config-pmap-c)
Command History
Release
Modification
12.0(28)S
This command was introduced.
12.2(28)SB
This command was integrated into Cisco IOS Release 12.2(28)SB.
12.4(20)T
Support was added for hierarchical queueing framework (HQF) using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC).
Usage Guidelines
You cannot use the random-detectcos-based command with the random-detectatm-clp-based command in the same HQF configuration. You must use the norandom-detectatm-clp-based command to disable it before you configure the random-detectcos-based command.
Examples
In the following example, WRED is configured on the basis of the CoS value. In this configuration, the random-detectcos-basedcommand has been configured and a CoS value of 2 has been specified.
Router> enable
Router# configure terminal
Router(config)# policy-map policymap1
Router(config-pmap)# class class1
Router(config-pmap-c)# random-detect cos-based 2
Router(config-pmap-c)#
end
Related Commands
Command
Description
random-detectatm-clp-based
Enables WRED on the basis of the ATM CLP of a packet.
random-detectclp
Specifies the ATM CLP value of a packet, the minimum and maximum thresholds, and the maximum probability denominator used for enabling WRED.
random-detectcos
Specifies the CoS value of a packet, the minimum and maximum thresholds, and the maximum probability denominator used for enabling WRED.
showpolicy-map
Displays the configuration of all classes for a specified service policy map or all classes for all existing policy maps.
showpolicy-mapinterface
Displays the packet statistics of all classes that are configured for all service policies either on the specified interface or subinterface or on a specific PVC on the interface.
random-detect discard-class
To configure the weighted random early detection (WRED) parameters for a discard-class value for a class policy in a policy map, use the
random-detectdiscard-class command in policy-map class configuration mode. To disable the discard-class values, use the
no form of this command.
Discard class. This is a number that identifies the drop eligibility of a packet. Valid values are 0 to 7.
min-threshold
Specifies the minimum number of packets allowed in the queue. When the average queue length reaches the minimum threshold, WRED randomly drops some packets with the specified DSCP, IP precedence, or discard-class value. Valid minimum threshold values are 1 to 512000000.
max-threshold
Specifies the maximum number of packets allowed in the queue. When the average queue length exceeds the maximum threshold, WRED drops all packets with the specified DSCP, IP precedence, or discard-class value. Valid maximum threshold values are 1 to 512000000.
max-probability-denominator
Denominator for the fraction of packets dropped when the average queue depth is at the maximum threshold. For example, if the denominator is 512, 1 out of every 512 packets is dropped when the average queue is at the maximum threshold. Valid values are 1 to 65535.
Command Default
For all precedence levels, the
max-probability-denominator default is 10 packets; that is, 1 out of every 10 packets is dropped at the maximum threshold.
Command Modes
Policy-map class configuration (config-pmap-c)
Command History
Release
Modification
12.0(3)T
This command was introduced.
12.2(13)T
This command was integrated into Cisco IOS Release 12.2(13)T.
12.2(28)SB
This command was integrated into Cisco IOS Release 12.2(28)SB.
12.2(31)SB
This command was integrated into Cisco IOS Release 12.2(31)SB and implemented on the Cisco 10000 series router.
15.2(2)T
This command was modified. The maximum and minimum threshold ranges were changed.
Usage Guidelines
When you configure the
random-detectdiscard-class command on an interface, packets are given preferential treatment based on the discard class of the packet. Use the
random-detectdiscard-class command to adjust the discard class for different discard-class values.
Note
While the range of values for the
min-threshold
and
max-threshold arguments is from 1 to 512000000, the actual values that you can specify depend on the type of random detect you are configuring. For example, the maximum threshold value cannot exceed the queue limit.
Cisco 10000 Series Router
You must first enable the drop mode using the
random-detectdiscard-class-based command. You can then set the drop probability profile using the
random-detectdiscard-class command.
The table below lists the default drop thresholds for WRED based on differentiated services code point (DSCP), IP precedence, and discard class. The drop probability indicates that the router drops one packet for every 10 packets.
Table 1 WRED Default Drop Thresholds
DSCP, Precedence, and Discard-Class Values
Minimum Threshold (Times the Queue Size)
Maximum Threshold (Times the Queue Size)
Drop Probability
All DSCPs
1/4
1/2
1/10
0
1/4
1/2
1/10
1
9/32
1/2
1/10
2
5/16
1/2
1/10
3
11/32
1/2
1/10
4
3/8
1/2
1/10
5
13/32
1/2
1/10
6
7/16
1/2
1/10
7
15/32
1/2
1/10
Examples
The following example shows how to configure discard class 2 to randomly drop packets when the average queue reaches the minimum threshold of 100 packets and 1 in 10 packets are dropped when the average queue is at the maximum threshold of 200 packets:
The following example shows how to enable discard-class-based WRED. In this example, the configuration of the class map named Silver indicates to classify traffic based on discard class 3 and 5. Traffic that matches discard class 3 or 5 is assigned to the class named Silver in the policy map named Premium. The Silver configuration includes WRED packet dropping based on discard class 5 with a minimum threshold of 500, maximum threshold of 1500, and a mark-probability-denominator of 200. The QoS policy is applied to PVC 1/81 on point-to-point ATM subinterface 2/0/0.2 in the outbound direction.
Specifies or modifies the bandwidth allocated for a class belonging to a policy map.
matchdiscard-class
Matches packets of a certain discard-class.
random-detectdiscard-class-based
Bases WRED on the discard class value of a packet.
random-detectexponential-weighting-constant
Configures the WRED and DWRED exponential weight factor for the average queue size calculation.
random-detectprecedence
Configures WRED and DWRED parameters for a particular IP precedence.
showpolicy-mapinterface
Displays the configuration of all classes configured for all service policies on the specified interface or displays the classes for the service policy for a specific PVC on the interface.
random-detect discard-class-based
To base weighted random early detection (WRED) on the discard class value of a packet, use the random-detectdiscard-class-based command in policy-map class configuration mode. To disable this feature, use the no form of this command.
random-detectdiscard-class-based
norandom-detectdiscard-class-based
Syntax Description
This command has no arguments or keywords.
Command Default
The defaults are router-dependent.
Command Modes
Policy-map class configuration
Command History
Release
Modification
12.2(13)T
This command was introduced.
12.2(28)SB
This command was integrated into Cisco IOS Release 12.2(28)SB.
Usage Guidelines
Enter this command so that WRED is based on the discard class instead of on the IP precedence field.
Examples
The following example shows that random detect is based on the discard class value of a packet:
policy-map name
class-name
bandwidth percent 40
random-detect discard-class-based
Related Commands
Command
Description
matchdiscard-class
Matches packets of a certain discard class.
random-detect dscp
Note
Effective with Cisco IOS Release 15.1(3)T, the
random-detectdscp command is hidden in interface configuration mode. Although this command is still available in Cisco IOS software, the CLI interactive Help does not display it if you enter a question mark at the command line. This command will be completely removed from interface configuration mode in a future release, which means that you will need to use the appropriate replacement command (or sequence of commands). For more information (including a list of replacement commands), see the “Legacy QoS Command Deprecation” feature document in the
Cisco IOS Quality of Service Solutions Configuration Guide.
To change the minimum and maximum packet thresholds for the differentiated services code point (DSCP) value, use the
random-detectdscp command in interface or QoS policy-map class configuration mode. To return the minimum and maximum packet thresholds to the default for the DSCP value, use the
no form of this command.
The DSCP value. The DSCP value can be a number from 0 to 63, or it can be one of the following keywords:
af11,
af12,
af13,
af21,
af22,
af23,
af31,
af32,
af33,
af41,
af42,
af43,
cs1,
cs2,
cs3,
cs4,
cs5,
cs7,
ef, or
rsvp.
min-threshold
Minimum threshold in number of packets. The value range of this argument is from 1 to 512000000. When the average queue length reaches the minimum threshold, Weighted Random Early Detection (WRED) or distributed WRED (dWRED) randomly drop some packets with the specified DSCP value.
max-threshold
Maximum threshold in number of packets. The value range of this argument is from the value of the
min-threshold argument to 512000000. When the average queue length exceeds the maximum threshold, WRED or dWRED drop all packets with the specified DSCP value.
mark-probability-denominator
(Optional) Denominator for the fraction of packets dropped when the average queue depth is at the maximum threshold. For example, if the denominator is 512, 1 out of every 512 packets is dropped when the average queue is at the maximum threshold. The value range is from 1 to 65536. The default is 10; that is, 1 out of every 10 packets is dropped at the maximum threshold.
Command Default
The default values for the
random-detectdscp command are different on Versatile Interface Processor (VIP)-enabled Cisco 7500 series routers and Catalyst 6000 family switches with a FlexWAN module (dWRED). All other platforms running WRED have another set of default values. For more information about
random-detectdscp defaults, see the “Usage Guidelines” section.
Command Modes
Interface configuration (config-if)
QoS policy-map class configuration (config-pmap-c)
Command History
Release
Modification
12.1(5)T
This command was introduced.
12.1(5a)E
This command was integrated into Cisco IOS Release 12.1(5a)E in policy-map class configuration mode only. This command was implemented on VIP-enabled Cisco 7500 series routers and Catalyst 6000 family switches with a FlexWAN module.
12.0(15)S
This command was integrated into Cisco IOS Release 12.0(15)S in QoS policy-map class configuration mode.
12.2(14)S
This command was integrated into Cisco IOS Release 12.2(14)S.
12.2(28)SB
This command was integrated into Cisco IOS Release 12.2(28)SB.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
15.1(3)T
This command was modified. This command was hidden in interface configuration mode.
15.2(2)T
This command was modified. The maximum and minimum threshold ranges were changed.
Cisco IOS XE Release 3.6S
This command was modified. Support was added for the Cisco ASR 903 router.
Usage Guidelines
Use the
random-detectdscp command in conjunction with the
random-detect command in interface configuration mode.
The
random-detectdscp command is available only if you specified the
dscp-based argument when using the
random-detect command in interface configuration mode.
Note
The
random-detectdscp command is not available at the interface level for Cisco IOS Release 12.1E or Release 12.0S. The
random-detectdscp command is available only in QoS policy-map class configuration mode in Cisco IOS Release 12.1E.
Defaults for VIP-Enabled Cisco 7500 Series Routers and Catalyst 6000 Family Switches with a FlexWAN Module
For all IP precedence values, the default
mark-probability-denominator is 10, and the
max-threshold value is based on the output buffering capacity and the transmission speed of the interface.
The default
min-threshold value depends on the IP precedence value. The
min-threshold value for IP precedence 0 corresponds to half of the
max-threshold value. The values for the remaining IP precedence values fall between half the
max-threshold value and the
max-threshold value at even intervals.
Note
Although the range of values for the
min-threshold
and
max-threshold arguments is from 1 to 512000000, the actual values that you can specify depend on the type of random detect you are configuring. For example, the maximum threshold value cannot exceed the queue limit.
Unless the maximum and minimum threshold values for the DSCP values are configured by the user, all DSCP values have the same minimum threshold and maximum threshold values as the value specified for precedence 0.
Specifying the DSCP Value
The
random-detectdscp command allows you to specify the DSCP value per traffic class. The DSCP value can be a number from 0 to 63, or it can be one of the following keywords:
af11,
af12,
af13,
af21,
af22,
af23,
af31,
af32,
af33,
af41,
af42,
af43,
cs1,
cs2,
cs3,
cs4,
cs5,
cs7,
ef, or
rsvp.
On a particular traffic class, eight DSCP values can be configured per traffic class. Overall, 29 values can be configured on a traffic class: 8 precedence values, 12 Assured Forwarding (AF) code points, 1 Expedited Forwarding code point, and 8 user-defined DSCP values.
Assured Forwarding Code Points
The AF code points provide a means for a domain to offer four different levels (four different AF classes) of forwarding assurances for IP packets received from other (such as customer) domains. Each one of the four AF classes is allocated a certain amount of forwarding services (buffer space and bandwidth).
Within each AF class, IP packets are marked with one of three possible drop precedence values (binary 2{010}, 4{100}, or 6{110}), which exist as the three lowest bits in the DSCP header. In congested network environments, the drop precedence value of the packet determines the importance of the packet within the AF class. Packets with higher drop precedence values are discarded before packets with lower drop precedence values.
The upper three bits of the DSCP value determine the AF class; the lower three values determine the drop probability.
Expedited Forwarding Code Points
The EF code point is usually used to mark high-priority, time-sensitive data. The EF code point marking is equal to the highest precedence value; therefore, the EF code point is always equal to precedence value 7.
Class Selector Values
The Class Selector (CS) values are equal to IP precedence values (for instance, cs1 is the same as IP precedence 1).
Default Values
The table below lists the default WRED minimum threshold value for each IP precedence value on the distributed platforms.
Table 2 Default WRED Minimum Threshold Values for the Distributed Platforms
IP
(Precedence)
Class Selector (CS) Value
Minimum Threshold Value (Fraction of Maximum Threshold Value)
Notes About the Value
0
cs0
8/16
All DSCP values that are not configured by the user will have the same threshold values as IP precedence 0.
1
cs1
9/16
--
2
cs2
10/16
--
3
cs3
11/16
--
4
cs4
12/16
--
5
cs5
13/16
--
6
cs6
14/16
--
7
cs7
15/16
The EF code point will always be equal to IP precedence 7.
Defaults for Non-VIP-Enabled Cisco 7500 Series Routers and Catalyst 6000 Family Switches with a FlexWAN Module
All platforms except the VIP-enabled Cisco 7500 series router and the Catalyst 6000 have the default values shown in the table below.
If WRED is using the DSCP value to calculate the drop probability of a packet, all 64 entries of the DSCP table are initialized with the default settings shown in the table below.
Table 3 random-detect dscp Default Settings
DSCP
(Precedence)
Minimum Threshold
Maximum Threshold
Mark Probability
0 (0)
20
40
1/10
1
22
40
1/10
2
24
40
1/10
3
26
40
1/10
4
28
40
1/10
5
30
40
1/10
6
32
40
1/10
7
34
40
1/10
8 (1)
22
40
1/10
9
22
40
1/10
10
24
40
1/10
11
26
40
1/10
12
28
40
1/10
13
30
40
1/10
14
32
40
1/10
15
34
40
1/10
16 (2)
24
40
1/10
17
22
40
1/10
18
24
40
1/10
19
26
40
1/10
20
28
40
1/10
21
30
40
1/10
22
32
40
1/10
23
34
40
1/10
24 (3)
26
40
1/10
25
22
40
1/10
26
24
40
1/10
27
26
40
1/10
28
28
40
1/10
29
30
40
1/10
30
32
40
1/10
31
34
40
1/10
32 (4)
28
40
1/10
33
22
40
1/10
34
24
40
1/10
35
26
40
1/10
36
28
40
1/10
37
30
40
1/10
38
32
40
1/10
39
34
40
1/10
40 (5)
30
40
1/10
41
22
40
1/10
42
24
40
1/10
43
26
40
1/10
44
28
40
1/10
45
30
40
1/10
46
36
40
1/10
47
34
40
1/10
48 (6)
32
40
1/10
49
22
40
1/10
50
24
40
1/10
51
26
40
1/10
52
28
40
1/10
53
30
40
1/10
54
32
40
1/10
55
34
40
1/10
56 (7)
34
40
1/10
57
22
40
1/10
58
24
40
1/10
59
26
40
1/10
60
28
40
1/10
61
30
40
1/10
62
32
40
1/10
63
34
40
1/10
rsvp
36
40
1/10
Examples
The following example enables WRED to use the DSCP value 8. The minimum threshold for the DSCP value 8 is 20, the maximum threshold is 40, and the mark probability is 1/10.
random-detect dscp 8 20 40 10
Related Commands
Command
Description
random-detect
Enables WRED or dWRED.
showqueueing
Lists all or selected configured queueing strategies.
showqueueinginterface
Displays the queueing statistics of an interface or VC.
random-detect dscp (aggregate)
To configure aggregate Weighted Random Early Detection (WRED) parameters for specific differentiated services code point (DSCP) value, use the
random-detectdscpvalues(aggregate)command in QoS policy-map class configuration mode. To disable configuration of aggregate WRED DSCP values, use the
no form of this command.
DSCP value(s) to which the following WRED profile parameter specifications are to apply. A maximum of eight subclasses (DSCP values) can be specified per command-line interface (CLI) entry. See the “Usage Guidelines” for a list of valid DSCP values.
min-thresh
The minimum number of packets allowed in the queue. When the average queue length reaches the minimum threshold, WRED randomly drops some packets with the specified DSCP value. Valid minimum threshold values are 1 to 16384.
max-thresh
The maximum number of packets allowed in the queue. When the average queue length exceeds the maximum threshold, WRED drops all packets with the specified DSCP value. Valid maximum threshold values are 1 to 16384.
mark-prob
The denominator for the fraction of packets dropped when the average queue depth is at the maximum threshold. For example, if the denominator is 512, 1 out of every 512 packets is dropped when the average queue is at the maximum threshold. Valid values are 1 to 65535.
Cisco10000SeriesRouter
valuessub-class-val1[...[subclass-val8]]
DSCP value(s) to which the following WRED profile parameter specifications are to apply. A maximum of 8 subclasses (DSCP values) can be specified per CLI entry. The DSCP value can be a number from 0 to 63, or it can be one of the following keywords:
ef,
af11,
af12,
af13,
af21,
af22,
af23,
af31,
af32,
af33,
af41,
af42,
af43,
cs1,
cs2,
cs3,
cs4,
cs5, or
cs7.
minimum-threshmin-thresh
Specifies the minimum number of packets allowed in the queue. When the average queue length reaches the minimum threshold, WRED randomly drops some packets with the specified DSCP value. Valid minimum threshold values are 1 to 16384.
maximum-threshmax-thresh
Specifies the maximum number of packets allowed in the queue. When the average queue length exceeds the maximum threshold, WRED drops all packets with the specified DSCP value. Valid maximum threshold values are 1 to 16384.
mark-probabilitymark-prob
Specifies the denominator for the fraction of packets dropped when the average queue depth is at the maximum threshold. For example, if the denominator is 512, 1 out of every 512 packets is dropped when the average queue is at the maximum threshold. Valid values are 1 to 65535.
Command Default
For all precedence levels, the mark-prob default value is 10 packets.
Command Modes
QoS policy-map class configuration
Command History
Release
Modification
12.2(18)SXE
This command was introduced.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2(31)SB2
This command was integrated into Cisco IOS Release 12.2(31)SB2 and implemented on the Cisco 10000 series router.
Usage Guidelines
For ATM interfaces, the Aggregate WRED feature requires that the ATM SPA cards are installed in a Cisco 7600 SIP-200 carrier card or a Cisco 7600 SIP-400 carrier card.
To configure WRED on an ATM interface, you must use therandom-detectaggregatecommands; the standard random-detect commands are no longer supported on ATM interfaces.
Use this command with a
random-detectaggregate command within a policy map configuration.
Repeat this command for each set of DSCP values that share WRED parameters.
After the policy map is defined, the policy map must be attached at the virtual circuit (VC) level.
The set of subclass (DSCP precedence) values defined on a
random-detectdscp(aggregate)CLI will be aggregated into a single hardware WRED resource. The statistics for these subclasses will also be aggregated.
Use the
showpolicy-mapinterface command to display the statistics for aggregated subclasses.
Cisco 10000 Series Router
For the PRE2, the random-detect command specifies the default profile for the queue. For the PRE3, the aggregate random-detect command is used instead to configure aggregate parameters for WRED. The PRE3 accepts the PRE2 random-detect command as a hidden command.
On the PRE2, accounting for the default profile is per precedence. On the PRE3, accounting and configuration for the default profile is per class map.
On the PRE2, the default threshold is per precedence for a DSCP or precedence value without an explicit threshold configuration. On the PRE3, the default threshold is to have no WRED configured.
On the PRE2, the drop counter for each precedence belonging to the default profile only has a drop count that matches the specific precedence value. Because the PRE2 has a default threshold for the default profile, the CBQOSMIB displays default threshold values. On the PRE3, the drop counter for each precedence belonging to the default profile has the aggregate counter of the default profile and not the individual counter for a specific precedence. The default profile on the PRE3 does not display any default threshold values in the CBQOSMIB if you do not configure any threshold values for the default profile.
DSCP Values
You must enter one or more differentiated service code point (DSCP) values. The command may include any combination of the following:
numbers (0 to 63) representing differentiated services code point values
af numbers (for example, af11) identifying specific AF DSCPs
cs numbers (for example, cs1) identifying specific CS DSCPs
default--Matches packets with the default DSCP.
ef--Matches packets with EF DSCP.
For example, if you wanted the DCSP values of 0, 1, 2, 3, 4, 5, 6, or 7 (note that only one of the IP DSCP values must be a successful match criterion, not all of the specified DSCP values), enter the
matchdscp01234567 command.
Examples
The following example shows how to create a class map named map1 and associate it with the policy map named map2. The configuration enables WRED to drop map1 packets based on DSCP 8 with a minimum threshold of 24 and a maximum threshold of 40. The map2 policy map is attached to the outbound ATM interface 1/0/0.
The following example shows a DSCP-based aggregate WRED configuration for an ATM interface. Note that first a policy map named dscp-aggr-wred is defined for the default class, then dscp-based aggregate WRED is enabled with the
random-detectdscp-basedaggregate command, then subclasses and WRED parameter values are assigned in a series of
random-detectdscp(aggregate)commands, and, finally, the policy map is attached at the ATM VC level using the
interfaceand
service-policy commands.
Router(config)# policy-map dscp-aggr-wred
Router(config-pmap)# class class-default
Router(config-pmap-c)# random-detect dscp-based aggregate minimum-thresh 1 maximum-thresh 10 mark-prob 10
!
! Define an aggregate subclass for packets with DSCP values of 0-7 and assign the WRED
! profile parameter values for this subclass
Router(config-pmap-c)# random-detect dscp 0 1 2 3 4 5 6 7 minimum-thresh 10 maximum-thresh 20 mark-prob 10
Router(config-pmap-c) random-detect dscp 8 9 10 11 minimum-thresh 10 maximum-thresh 40 mark-prob 10
Router(config)# interface ATM4/1/0.11 point-to-point
Router(config-subif)# ip address 10.0.0.2 255.255.255.0
Router(config-subif) pvc 11/101
Router(config-subif)# service-policy output dscp-aggr-wred
Examples
The following example shows how to create a class map named Gold and associate it with the policy map named Business. The configuration enables WRED to drop Gold packets based on DSCP 8 with a minimum threshold of 24 and a maximum threshold of 40. The Business policy map is attached to the outbound ATM interface 1/0/0.
Specifies the name of the class whose policy you want to create or change, and the default class (commonly known as the class-default class) before you configure its policy.
interface
Configures an interface type and enters interface configuration mode.
policy-map
Creates a policy map that can be attached to one or more interfaces to specify a service policy.
random-detectaggregate
Enables aggregate WRED and optionally specifies default WRED parameter values for a default aggregate class. This default class will be used for all subclasses that have not been explicitly configured.
service-policy
Attaches a policy map to an input interface or VC, or an output interface or VC, to be used as the service policy for that interface or VC.
showpolicy-mapinterface
Displays the configuration of all classes configured for all service policies on the specified interface or displays the classes for the service policy for a specific PVC on the interface.
random-detect ecn
To enable explicit congestion notification (ECN), use the random-detectecncommand in policy-map class configuration mode. To disable ECN, use the no form of this command.
random-detectecn
norandom-detectecn
Syntax Description
This command has no arguments or keywords.
Command Default
By default, ECN is disabled.
Command Modes
Policy-map class configuration
Command History
Release
Modification
12.2(8)T
This command was introduced.
Usage Guidelines
If ECN is enabled, ECN can be used whether Weighted Random Early Detection (WRED) is based on the IP precedence value or the differentiated services code point (DSCP) value.
Examples
The following example enables ECN in a policy map called “pol1”:
Router(config)# policy-map pol1
Router(config-pmap)# class class-default
Router(config-pmap)# bandwidth per 70
Router(config-pmap-c)# random-detect
Router(config-pmap-c)# random-detect ecn
Related Commands
Command
Description
showpolicy-map
Displays the configuration of all classes for a specified service policy map or all classes for all existing policy maps.
showpolicy-mapinterface
Displays the packet statistics of all classes that are configured for all service policies either on the specified interface or subinterface or on a specific PVC on the interface.
random-detect exponential-weighting-constant
Note
Effective with Cisco IOS Release 15.0(1)S and Cisco IOS Release 15.1(3)T, the
random-detectexponential-weighting-constantcommand is hidden in interface configuration mode. Although this command is still available in Cisco IOS software, the CLI interactive Help does not display it if you attempt to view it by entering a question mark at the command line. This command will be completely removed from interface configuration mode in a future release, which means that you will need to use the appropriate replacement command (or sequence of commands). For more information (including a list of replacement commands), see the "Legacy QoS Command Deprecation" feature document in the
Cisco IOS Quality of Service Solutions Configuration Guide.
To configure the Weighted Random Early Detection (WRED) and distributed WRED (DWRED) exponential weight factor for the average queue size calculation for the queue, use the
random-detectexponential-weighting-constantcommand in interface configuration mode. To configure the exponential weight factor for the average queue size calculation for the queue reserved for a class, use the
random-detectexponential-weighting-constantcommand in policy-map class configuration mode. To return the value to the default, use the
no form of this command.
Exponent from 1 to 16 used in the average queue size calculation.
Command Default
The default exponential weight factor is 9.
Command Modes
Interface configuration when used on an interface
Policy-map class configuration when used to specify class policy in a policy map or when used in the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC)
Command History
Release
Modification
11.1CC
This command was introduced.
12.0(5)T
This command was made available as a QoS policy-map class configuration command.
12.0(5)XE
This command was integrated into Cisco IOS Release 12.0(5)XE and implemented on Versatile Interface Processor (VIP) enabled Cisco 7500 series routers.
12.1(5)T
This command was integrated into Cisco IOS Release 12.1(5)T and implemented on VIP-enabled Cisco 7500 series routers.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2(31)SB
This command was integrated into Cisco IOS Release 12.2(31)SB and implemented on the Cisco 10000 series router.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
15.0(1)S
This command was modified. This command was hidden in interface configuration mode.
15.1(3)T
This command was modified. This command was hidden in interface configuration mode.
Usage Guidelines
WRED is a congestion avoidance mechanism that slows traffic by randomly dropping packets when congestion exists. DWRED is similar to WRED but uses the VIP instead of the Route Switch Processor (RSP). WRED and DWRED are most useful with protocols like TCP that respond to dropped packets by decreasing the transmission rate.
Use this command to change the exponent used in the average queue size calculation for the WRED and DWRED services. You can also use this command to configure the exponential weight factor for the average queue size calculation for the queue reserved for a class.
Note
The default WRED or DWRED parameter values are based on the best available data. We recommend that you do not change the parameters from their default values unless you have determined that your applications would benefit from the changed values.
The DWRED feature is not supported for class policy.
The DWRED feature is supported only on Cisco 7000 series routers with an RSP7000 card and Cisco 7500 series routers with a VIP2-40 or greater interface processor. A VIP2-50 interface processor is strongly recommended when the aggregate line rate of the port adapters on the VIP is greater than DS3. A VIP2-50 interface processor is required for OC-3 rates.
To use DWRED, distributed Cisco Express Forwarding (dCEF) switching must first be enabled on the interface. For more information on dCEF, refer to the Cisco IOS IP Switching Configuration Guide and the Cisco IOS IP Switching Command Reference.
Examples
The following example configures WRED on an interface with a weight factor of 10:
interface Hssi0/0/0
description 45Mbps to R1
ip address 10.200.14.250 255.255.255.252
random-detect
random-detect exponential-weighting-constant 10
The following example configures the policy map called policy1 to contain policy specification for the class called class1. During times of congestion, WRED packet drop is used instead of tail drop. The weight factor used for the average queue size calculation for the queue for class1 is 12.
! The following commands create the class map called class1:
class-map class1
match input-interface FE0/1
! The following commands define policy1 to contain policy specification for class1:
policy-map policy1
class class1
bandwidth 1000
random-detect
random-detect exponential-weighting-constant 12
The following example configures policy for a traffic class named int10 to configure the exponential weight factor as 12. This is the weight factor used for the average queue size calculation for the queue for traffic class int10. WRED packet drop is used for congestion avoidance for traffic class int10, not tail drop.
policy-map policy12
class int10
bandwidth 2000
random-detect exponential-weighting-constant 12
Related Commands
Command
Description
bandwidth(policy-mapclass)
Specifies or modifies the bandwidth allocated for a class belonging to a policy map.
exponential-weighting-constant
Configures the exponential weight factor for the average queue size calculation for a WRED parameter group.
fair-queue(class-default)
Specifies the number of dynamic queues to be reserved for use by the class-default class as part of the default class policy.
precedence
Configures precedence levels for a VC or PVC class that can be assigned to a VC or PVC bundle and thus applied to all of the members of that bundle.
precedence(WREDgroup)
Configures a WRED group for a particular IP Precedence.
random-detectdscp
Changes the minimum and maximum packet thresholds for the DSCP value.
random-detect(perVC)
Enables per-VC WRED or per-VC DWRED.
random-detectprecedence
Configures WRED and DWRED parameters for a particular IP Precedence.
showpolicy-map
Displays the configuration of all classes for a specified service policy map or all classes for all existing policy maps.
showpolicy-mapinterface
Displays the configuration of all classes configured for all service policies on the specified interface or displays the classes for the service policy for a specific PVC on the interface.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueueing
Lists all or selected configured queueing strategies.
random-detect flow
Note
Effective with Cisco IOS Release 15.1(3)T, the
random-detectflowcommand is hidden. Although this command is still available in Cisco IOS software, the CLI interactive Help does not display it if you attempt to view it by entering a question mark at the command line. This command will be completely removed in a future release. For more information, see the "Legacy QoS Command Deprecation" feature document in the
Cisco IOS Quality of Service Solutions Configuration Guide.
To enable flow-based Weighted Random Early Detection ( WRED), use the
random-detectflowcommand in interface configuration mode. To disable flow-based WRED, use the
no form of this command.
random-detectflow
norandom-detectflow
Syntax Description
This command has no arguments or keywords.
Command Default
Flow-based WRED is disabled by default.
Command Modes
Interface configuration
Command History
Release
Modification
12.0(3)T
This command was introduced.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
15.1(3)T
This command was modified. This command was hidden.
Usage Guidelines
You must use this command to enable flow-based WRED before you can use the
random-detectflowaverage-depth-factor and
random-detectflowcount commands to further configure the parameters of flow-based WRED.
Before you can enable flow-based WRED, you must enable and configure WRED. For complete information, refer to the
Cisco IOS Quality of Service Solutions Configuration Guide .
Examples
The following example enables flow-based WRED on serial interface 1:
Changes the minimum and maximum packet thresholds for the DSCP value.
random-detectexponential-weighting-constant
Configures the WRED and DWRED exponential weight factor for the average queue size calculation.
random-detectflowaverage-depth-factor
Sets the multiplier to be used in determining the average depth factor for a flow when flow-based WRED is enabled.
random-detectflowcount
Sets the flow count for flow-based WRED.
random-detectprecedence
Configures WRED and DWRED parameters for a particular IP Precedence.
showinterfaces
Displays the statistical information specific to a serial interface.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueueing
Lists all or selected configured queueing strategies.
random-detect flow average-depth-factor
Note
Effective with Cisco IOS Release 15.1(3)T, the
random-detectflowaverage-depth-factorcommand is hidden. Although this command is still available in Cisco IOS software, the CLI interactive Help does not display it if you attempt to view it by entering a question mark at the command line. This command will be completely removed in a future release. For more information, see the "Legacy QoS Command Deprecation" feature document in the
Cisco IOS Quality of Service Solutions Configuration Guide.
To set the multiplier to be used in determining the average depth factor for a flow when flow-based Weighted Random Early Detection (WRED) is enabled, use the
random-detectflowaverage-depth-factorcommand in interface configuration mode. To remove the current flow average depth factor value, use the
no form of this command.
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
15.1(3)T
This command was modified. This command was hidden.
Usage Guidelines
Use this command to specify the scaling factor that flow-based WRED should use in scaling the number of buffers available per flow and in determining the number of packets allowed in the output queue for each active flow. This scaling factor is common to all flows. The outcome of the scaled number of buffers becomes the per-flow limit.
If this command is not used and flow-based WRED is enabled, the average depth scaling factor defaults to 4.
A flow is considered nonadaptive--that is, it takes up too much of the resources--when the average flow depth times the specified multiplier (scaling factor) is less than the depth for the flow, for example:
Before you use this command, you must use the
random-detectflow command to enable flow-based WRED for the interface. To configure flow-based WRED, you may also use the
random-detectflowcount command.
Examples
The following example enables flow-based WRED on serial interface 1 and sets the scaling factor for the average flow depth to 8:
Changes the minimum and maximum packet thresholds for the DSCP value.
random-detectexponential-weighting-constant
Configures the WRED and DWRED exponential weight factor for the average queue size calculation.
random-detectflow
Enables flow-based WRED.
random-detectflowcount
Sets the flow count for flow-based WRED.
random-detectprecedence
Configures WRED and DWRED parameters for a particular IP Precedence.
showinterfaces
Displays the statistical information specific to a serial interface.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueueing
Lists all or selected configured queueing strategies.
random-detect flow count
Note
Effective with Cisco IOS Release 15.1(3)T, the
random-detectflowcountcommand is hidden. Although this command is still available in Cisco IOS software, the CLI interactive Help does not display it if you attempt to view it by entering a question mark at the command line. This command will be completely removed in a future release. For more information, see the "Legacy QoS Command Deprecation" feature document in the
Cisco IOS Quality of Service Solutions Configuration Guide.
To set the flow count for flow-based Weighted Random Early Detection (WRED), use the
random-detectflowcountcommand in interface configuration mode. To remove the current flow count value, use the
no form of this command.
random-detectflowcountnumber
norandom-detectflowcountnumber
Syntax Description
number
Specifies a value from 16 to 215 (32768).
Command Default
256
Command Modes
Interface configuration
Command History
Release
Modification
12.0(3)T
This command was introduced.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
15.1(3)T
This command was modified. This command was hidden.
Usage Guidelines
Before you use this command, you must use the
random-detectflow command to enable flow-based WRED for the interface.
Examples
The following example enables flow-based WRED on serial interface 1 and sets the flow threshold constant to 16:
Changes the minimum and maximum packet thresholds for the DSCP value.
random-detectexponential-weighting-constant
Configures the WRED and DWRED exponential weight factor for the average queue size calculation.
random-detectflow
Enables flow-based WRED.
random-detectprecedence
Configures WRED and DWRED parameters for a particular IP Precedence.
showinterfaces
Displays the statistical information specific to a serial interface.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueueing
Lists all or selected configured queueing strategies.
random-detect prec-based
Note
Effective with Cisco IOS Release 12.4(20)T, the random-detectprec-basedcommandisreplacedbytherandom-detectprecedence-basedcommand.Seetherandom-detectprecedence-basedcommand formoreinformation.
To base weighted random early detection (WRED) on the precedence value of a packet, use the random-detectprec-based command in policy-map class configuration mode. To disable this feature, use the no form of this command.
random-detectprec-based
norandom-detectprec-based
Syntax Description
This command has no arguments or keywords.
Command Default
WRED is disabled by default.
Command Modes
Policy-map class configuration (config-pmap-c)
Command History
Release
Modification
12.0(28)S
This command was introduced.
12.2(28)SB
This command was integrated into Cisco IOS Release 12.2(28)SB.
12.4(20)T
This command was replaced by the random-detectprecedence-based command within a policy map.
Usage Guidelines
With the random-detectprec-based command, WRED is based on the IP precedence value of the packet.
Use the random-detectprec-based command before configuring the random-detectprecedence command.
Beginning with Cisco IOS Release 12.4(20)T, use the random-detectprecedence command when you configure a policy map.
Examples
The following example shows that random detect is based on the precedence value of a packet:
Router> enable
Router# configure terminal
Router(config)#
policy-map policy1
Router(config-pmap)# class class1
Router(config-pmap-c)# bandwidth percent 80
Router(config-pmap-c)# random-detect precedence-based
Router(config-pmap-c)# random-detect precedence 2 500 ms 1000 ms
Router(config-pmap-c)# exit
Related Commands
Command
Description
random-detect
Enables WRED or DWRED.
random-detectprecedence
Configures the WRED and DWRED parameters for a particular IP precedence; configures WRED parameters for a particular IP precedence for a class policy in a policy map.
random-detect precedence
Note
Effective with Cisco IOS Release 15.0(1)S and Cisco IOS Release 15.1(3)T, the
random-detectprecedence command is hidden in interface configuration mode. Although this command is still available in Cisco IOS software, the CLI interactive Help does not display it if you enter a question mark at the command line. This command will be completely removed from interface configuration mode in a future release, which means that you will need to use the appropriate replacement command (or sequence of commands). For more information (including a list of replacement commands), see the “Legacy QoS Command Deprecation” feature document in the
Cisco IOS Quality of Service Solutions Configuration Guide.
To configure Weighted Random Early Detection (WRED) and distributed WRED (dWRED) parameters for a particular IP precedence, use the
random-detectprecedence command in interface configuration mode. To configure WRED parameters for a particular IP precedence for a class policy in a policy map, use the
random-detectprecedence command in QoS policy-map class configuration mode. To return the values to the default for the precedence, use the
no form of this command.
IP precedence number. The value range is from 0 to 7. For Cisco 7000 series routers with an RSP7000 interface processor and Cisco 7500 series routers with a VIP2-40 interface processor (the VIP2-50 interface processor is strongly recommended), the precedence value range is from 0 to 7; see Table 1 in the “Usage Guidelines” section.
Minimum threshold in number of packets. The value range of this argument is from 1 to 512000000. When the average queue length reaches the minimum threshold, WRED or dWRED randomly drop some packets with the specified IP precedence.
max-threshold
Maximum threshold in number of packets. The value range of this argument is from the value of the
min-threshold argument to 512000000. When the average queue length exceeds the maximum threshold, WRED or dWRED drop all packets with the specified IP precedence.
mark-probability-denominator
Denominator for the fraction of packets dropped when the average queue depth is at the maximum threshold. For example, if the denominator is 512, 1 out of every 512 packets is dropped when the average queue is at the maximum threshold. The value range is from 1 to 65536. The default is 10; that is 1 out of every 10 packets is dropped at the maximum threshold.
Command Default
For all precedences, the
mark-probability-denominator default value is 10, and the
max-threshold value is based on the output buffering capacity and the transmission speed for the interface.
The default
min-threshold value depends on the precedence. The
min-threshold value for IP precedence 0 corresponds to half of the
max-threshold value. The values for the remaining precedences fall between half the
max-threshold value and the
max-threshold value at evenly spaced intervals. See the table in the “Usage Guidelines” section of this command for a list of the default minimum threshold values for each IP precedence.
Command Modes
Interface configuration (config-if)
QoS policy-map class configuration (config-pmap-c)
Command History
Release
Modification
11.1CC
This command was introduced.
12.2(28)SB
This command was integrated into Cisco IOS Release 12.2(28)SB.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
12.4(20)T
Support was added for hierarchical queueing framework (HQF) using the modular quality of service (QoS) CLI (MQC).
Note
This command replaces the
random-detectprec-based command in QoS policy-map configuration mode.
15.0(1)S
This command was modified. This command was hidden in interface configuration mode.
15.1(3)T
This command was modified. This command was hidden in interface configuration mode.
15.2(2)T
This command was modified. The maximum and minimum threshold ranges were changed.
Cisco IOS XE Release 3.6S
This command was modified. Support was added for the Cisco ASR 903 router.
Usage Guidelines
WRED is a congestion avoidance mechanism that slows traffic by randomly dropping packets when congestion exists. dWRED is similar to WRED but uses the Versatile Interface Processor (VIP) instead of the Route Switch Processor (RSP).
When you configure the
random-detect command on an interface, packets are given preferential treatment based on the IP precedence of the packet. Use the
random-detectprecedence command to adjust the treatment for different precedences.
If you want WRED or dWRED to ignore the precedence when determining which packets to drop, enter this command with the same parameters for each precedence. Remember to use appropriate values for the minimum and maximum thresholds.
Note that if you use the
random-detectprecedence command to adjust the treatment for different precedences within class policy, you must ensure that WRED is not configured for the interface to which you attach that service policy.
Note
Although the range of values for the
min-threshold
and
max-threshold arguments is from 1 to 512000000, the actual values that you can specify depend on the type of random detect you are configuring. For example, the maximum threshold value cannot exceed the queue limit.
The table below lists the default minimum threshold value for each IP precedence.
Table 4 Default WRED and dWRED Minimum Threshold Values
Minimum Threshold Value (Fraction of Maximum Threshold Value)
IP Precedence
WRED
dWRED
0
9/18
8/16
1
10/18
9/16
2
11/18
10/16
3
12/18
11/16
4
13/18
12/16
5
14/18
13/16
6
15/18
14/16
7
16/18
15/16
rsvp
17/18
—
Note
The default WRED or dWRED parameter values are based on the best available data. We recommend that you do not change the parameters from their default values unless you have determined that your applications would benefit from the changed values.
The dWRED feature is supported only on Cisco 7000 series routers with an RSP7000 card and Cisco 7500 series routers with a VIP2-40 or higher interface processor. A VIP2-50 interface processor is strongly recommended when the aggregate line rate of the port adapters on the VIP is greater than DS3. A VIP2-50 interface processor is required for OC-3 rates.
To use dWRED, distributed Cisco Express Forwarding (dCEF) switching must first be enabled on the interface. For more information on dCEF, refer to the
Cisco IOS IP Switching Configuration Guide and the
Cisco IOS IP Switching Command Reference.
Note
The dWRED feature is not supported in a class policy.
Examples
The following example shows the configuration to enable WRED on the interface and to specify parameters for the different IP precedences:
The following example shows the configuration for the policy for a class called acl10 included in a policy map called policy10. Class acl101 has these characteristics: a minimum of 2000 kb/s of bandwidth are expected to be delivered to this class in the event of congestion and a weight factor of 10 is used to calculate the average queue size. For congestion avoidance, WRED packet drop is used, not tail drop. IP precedence is reset for levels 0 through 4.
Specifies or modifies the bandwidth allocated for a class belonging to a policy map.
fair-queue(class-default)
Specifies the number of dynamic queues to be reserved for use by the class-default class as part of the default class policy.
random-detect(perVC)
Enables per-VC WRED or per-VC dWRED.
random-detectdscp
Changes the minimum and maximum packet thresholds for the DSCP value.
random-detectexponential-weighting-constant
Configures the WRED and dWRED exponential weight factor for the average queue size calculation.
random-detectflowcount
Sets the flow count for flow-based WRED.
showpolicy-mapinterface
Displays the configuration of all classes configured for all service policies on the specified interface or displays the classes for the service policy for a specific PVC on the interface.
showqueue
Displays the contents of packets inside a queue for a particular interface or VC.
showqueuing
Lists all or selected configured queuing strategies.
random-detect precedence (aggregate)
To configure aggregate Weighted Random Early Detection (WRED) parameters for specific IP precedence value(s), use the
random-detectprecedence(aggregate)command in policy-map class configuration mode. To disable configuration of aggregate WRED precedence values, use the
no form of this command.
IP precedence value to which the following WRED profile parameter specifications are to apply. Up to four subclasses (IP precedence values) can be specified per command line interface (CLI) entry. The value range is from 0 to 7.
min-thresh
Minimum threshold (in number of packets) for the subclass(es). Valid values are from 1 to 12288.
max-thresh
Specifies the maximum threshold (in number of packets) for the subclass(es). Valid values are from the minimum threshold argument to 12288.
mark-prob
Specifies the denominator for the fraction of packets dropped when the average queue depth is at the maximum threshold for the subclass(es). Valid values are from 1 to 255.
Cisco10000SeriesRouter
sub-class-val1[...[subclass-val8]]
IP precedence value(s) to which the following WRED profile parameter specifications are to apply. A maximum of 8 subclasses (IP precedence values) can be specified per CLI entry. The value range is from 0 to 7.
minimum-threshmin-thresh
Specifies the minimum number of packets allowed in the queue. When the average queue length reaches the minimum threshold, WRED randomly drops some packets with the specified IP precedence value. Valid minimum threshold values are 1 to 16384.
maximum-threshmax-thresh
Specifies the maximum number of packets allowed in the queue. When the average queue length exceeds the maximum threshold, WRED drops all packets with the specified IP precedence value. Valid maximum threshold values are 1 to 16384.
mark-probabilitymark-prob
Specifies the denominator for the fraction of packets dropped when the average queue depth is at the maximum threshold. For example, if the denominator is 512, 1 out of every 512 packets is dropped when the average queue is at the maximum threshold. Valid values are 1 to 65535.
Cisco 10000 Series Router
For all precedence levels, the mark-prob default is 10 packets.
Command Modes
Policy-map class configuration
Command History
Release
Modification
12.0(17)SL
This command was introduced on the Cisco 10000 series router.
12.2(18)SXE
This command was introduced.
12.2(31)SB
This command was integrated into Cisco IOS Release 12.2(31)SB and implemented on the Cisco 10000 series router for the PRE3.
Usage Guidelines
For ATM interfaces, the Aggregate WRED feature requires that the ATM SPA cards are installed in a Cisco 7600 SIP-200 carrier card or a Cisco 7600 SIP-400 carrier card.
To configure WRED on an ATM interface, you must use the random-detect aggregate commands; the standard random-detect commands are no longer supported on ATM interfaces
Use this command with a
random-detectaggregate command within a policy map configuration.
Repeat this command for each set of IP precedence values that share WRED parameters.
After the policy map is defined, the policy map must be attached at the VC level.
The set of subclass (IP precedence) values defined on a
random-detectprecedence(aggregate)CLI will be aggregated into a single hardware WRED resource. The statistics for these subclasses will also be aggregated.
Use the
showpolicy-mapinterface command to display the statistics for aggregated subclasses.
Cisco 10000 Series Router
The table below lists the default drop thresholds for WRED based on DSCP, IP precedence, and discard-class. The drop probability indicates that the router drops one packet for every 10 packets.
Table 5 WRED Default Drop Thresholds
DSCP, Precedence, and Discard-Class Values
Minimum Threshold (times the queue size)
Maximum Threshold (times the queue size)
Drop Probability
All DSCPs
1/4
1/2
1/10
0
1/4
1/2
1/10
1
9/32
1/2
1/10
2
5/16
1/2
1/10
3
11/32
1/2
1/10
4
3/8
1/2
1/10
5
13/32
1/2
1/10
6
7/16
1/2
1/10
7
15/32
1/2
1/10
For the PRE2, the random-detect command specifies the default profile for the queue. For the PRE3, the aggregate random-detect command is used instead to configure aggregate parameters for WRED. The PRE3 accepts the PRE2 random-detect command as a hidden CLI.
On the PRE2, accounting for the default profile is per precedence. On the PRE3, accounting and configuration for the default profile is per class map.
On the PRE2, the default threshold is per precedence for a DSCP or precedence value without an explicit threshold configuration. On the PRE3, the default threshold is to have no WRED configured.
On the PRE2, the drop counter for each precedence belonging to the default profile only has a drop count that matches the specific precedence value. Because the PRE2 has a default threshold for the default profile, the CBQOSMIB displays default threshold values. On the PRE3, the drop counter for each precedence belonging to the default profile has the aggregate counter of the default profile and not the individual counter for a specific precedence. The default profile on the PRE3 does not display any default threshold values in the CBQOSMIB if you do not configure any threshold values for the default profile.
Examples
Examples
The following example shows how to enable IP precedence-based WRED on the Cisco 10000 series router. In this example, the configuration of the class map named Class1 indicates to classify traffic based on IP precedence 3, 4, and 5. Traffic that matches IP precedence 3, 4, or 5 is assigned to the class named Class1 in the policy map named Policy1. WRED-based packet dropping is configured for Class1 and is based on IP precedence 3 with a minimum threshold of 500, maximum threshold of 1500, and a mark-probability-denominator of 200. The QoS policy is applied to PVC 1/32 on the point-to-point ATM subinterface 1/0/0.1.
Specifies the name of the class whose policy you want to create or change, and the default class (commonly known as the class-default class) before you configure its policy.
interface
Configures an interface type and enters interface configuration mode.
policy-map
Creates a policy map that can be attached to one or more interfaces to specify a service policy.
random-detectaggregate
Enables aggregate WRED and optionally specifies default WRED parameter values for a default aggregate class. This default class will be used for all subclasses that have not been explicitly configured.
service-policy
Attaches a policy map to an input interface or VC, or an output interface or VC, to be used as the service policy for that interface or VC.
showpolicy-mapinterface
Displays the configuration of all classes configured for all service policies on the specified interface or displays the classes for the service policy for a specific PVC on the interface.
random-detect-group
Note
Effective with Cisco IOS Release 15.0(1)S and Cisco IOS Release 15.1(3)T, the
random-detect-groupcommand is hidden. Although this command is still available in Cisco IOS software, the CLI interactive Help does not display it if you attempt to view it by entering a question mark at the command line. This command will be completely removed in a future release. For more information, see the "Legacy QoS Command Deprecation" feature document in the
Cisco IOS Quality of Service Solutions Configuration Guide.
To define the Weighted Random Early Detection (WRED) or distributed WRED (DWRED) parameter group, use the
random-detect-groupcommand in global configuration mode. To delete the WRED or DWRED parameter group, use the
no form of this command.
(Optional) Specifies that WRED is to use the differentiated services code point (DSCP) value when it calculates the drop probability for a packet.
prec-based
(Optional) Specifies that WRED is to use the IP Precedence value when it calculates the drop probability for a packet.
Command Default
No WRED or DWRED parameter group exists.
If you choose not to use either the
dscp-based or the
prec-based keywords, WRED uses the IP Precedence value (the default method) to calculate drop probability for the packet.
Command Modes
Global configuration
Command History
Release
Modification
11.1(22)CC
This command was introduced.
12.1(5)T
This command was integrated into Cisco IOS Release 12.1(5)T. Keywords
dscp-based and
prec-based were added to support Differentiated Services (DiffServ) and Assured Forwarding (AF) Per Hop Behavior (PHB).
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX train. Support in a specific 12.2SX release of this train depends on your feature set, platform, and platform hardware.
15.0(1)S
This command was modified. This command was hidden.
15.1(3)T
This command was modified. This command was hidden.
Usage Guidelines
WRED is a congestion avoidance mechanism that slows traffic by randomly dropping packets when there is congestion. DWRED is similar to WRED but uses the Versatile Interface Processor (VIP) instead of the Route Switch Processor (RSP). WRED and DWRED are most useful when the traffic uses protocols such as TCP that respond to dropped packets by decreasing the transmission rate.
The router automatically determines parameters to use in the WRED calculations. If you want to change these parameters for a group, use the
exponential-weighting-constantor
precedence command.
Two Methods for Calculating the Drop Probability of a Packet
This command includes two optional arguments,
dscp-based and
prec-based, that determine the method WRED uses to calculate the drop probability of a packet.
Note the following points when deciding which method to instruct WRED to use:
With the
dscp-basedkeyword, WRED uses the DSCP value (that is, the first six bits of the IP type of service (ToS) byte) to calculate the drop probability.
With the
prec-based keyword, WRED will use the IP Precedence value to calculate the drop probability.
The
dscp-based and
prec-based keywords are mutually exclusive.
If neither argument is specified, WRED uses the IP Precedence value to calculate the drop probability (the default method).
Examples
The following example defines the WRED parameter group called sanjose:
The following example enables WRED to use the DSCP value 9. The minimum threshold for the DSCP value 9 is 20 and the maximum threshold is 50. This configuration can be attached to other virtual circuits (VCs) as required.
Changes the minimum and maximum packet thresholds for the DSCP value.
exponential-weighting-constant
Configures the exponential weight factor for the average queue size calculation for a WRED parameter group.
precedence(WREDgroup)
Configures a WRED group for a particular IP Precedence.
random-detect(perVC)
Enables per-VC WRED or per-VC VIP-distributed WRED.
showqueueing
Lists all or selected configured queueing strategies.
showqueueinginterface
Displays the queueing statistics of an interface or VC.
rate-limit
To configure committed access rate (CAR) and distributed committed
access rate (DCAR) policies, use the
rate-limit command in interface configuration
mode. To remove the rate limit from the configuration, use the
no form of this command.
Applies this CAR traffic policy to packets received on this
input interface.
output
Applies this CAR traffic policy to packets sent on this
output interface.
bps
Average rate, in bits per second (bps). The value must be
in increments of 8 kbps. The value is a number from 8000 to 2000000000.
access-group
(Optional) Applies this CAR traffic policy to the specified
access list.
acl-index
(Optional) Access list number. Values are numbers from 1 to
2699.
rate-limit
(Optional) The access list is a rate-limit access list.
rate-limit-acl-index
(Optional) Rate-limit access list number. Values are
numbers from 0 to 99.
dscp
(Optional) Allows the rate limit to be applied to any
packet matching a specified differentiated services code point (DSCP).
dscp-value
(Optional) The DSCP number. Values are numbers from 0 to
63.
qos-group
(Optional) Allows the rate limit to be applied to any
packet matching a specified qos-group number. Values are numbers from 0 to 99.
qos-group-number
(Optional) The qos-group number. Values are numbers from 0
to 99.
burst-normal
Normal burst size, in bytes. The minimum value is bps
divided by 2000. The value is a number from 1000 to 512000,000.
burst-max
Excess burst size, in bytes. The value is a number from
2000 to 1024000000.
conform-actionconform-action
Action to take on packets that conform to the specified
rate limit. Specify one of the following keywords:
continue--Evaluate
the next
rate-limit command.
drop--Drop
the packet.
set-dscp-continue--Set
the differentiated services codepoint (DSCP) (0 to 63) and evaluate the next
rate-limit command.
set-dscp-transmit--Transmit
the DSCP and transmit the packet.
set-mpls-exp-imposition-continue--Set
the Multiprotocol Label Switching (MPLS) experimental bits (0 to 7) during
imposition and evaluate the next
rate-limit command.
set-mpls-exp-imposition-transmit--Set
the MPLS experimental bits (0 to 7) during imposition and transmit the packet.
set-prec-continue--Set
the IP precedence (0 to 7) and evaluate the next
rate-limit command.
set-prec-transmit--Set
the IP precedence (0 to 7) and transmit the packet.
set-qos-continue--Set
the quality of service (QoS) group ID (1 to 99) and evaluate the next
rate-limit command.
set-qos-transmit--Set
the QoS group ID (1 to 99) and transmit the packet.
transmit--Transmit
the packet.
exceed-actionexceed-action
Action to take on packets that exceed the specified rate
limit. Specify one of the following keywords:
continue--Evaluate
the next
rate-limit command.
drop--Drop
the packet.
set-dscp-continue--Set
the DSCP (0 to 63) and evaluate the next
rate-limit command.
set-dscp-transmit--Transmit
the DSCP and transmit the packet.
set-mpls-exp-imposition-continue--Set
the MPLS experimental bits (0 to 7) during imposition and evaluate the next
rate-limit command.
set-mpls-exp-imposition-transmit--Set
the MPLS experimental bits (0 to 7) during imposition and transmit the packet.
set-prec-continue--Set
the IP precedence (0 to 7) and evaluate the next
rate-limit command.
set-prec-transmit--Set
the IP precedence (0 to 7) and transmit the packet.
set-qos-continue--Set
the QoS group ID (1 to 99) and evaluate the next
rate-limit command.
set-qos-transmit--Set
the QoS group ID (1 to 99) and transmit the packet.
transmit--Transmit
the packet.
Command Default
CAR and DCAR are disabled.
Command Modes
Interface configuration
Command History
Release
Modification
11.1 CC
This command was introduced.
12.1(5)T
The
conform and
exceed keywords for the MPLS
experimental field were added.
12.2(4)T
This command was implemented on the Cisco MGX 8850 switch
and the MGX 8950 switch with a Cisco MGX RPM-PR card.
12.2(4)T2
This command was implemented on the Cisco 7500 series
routers.
12.2(33)SRA
This command was integrated into Cisco IOS Release
12.2(33)SRA.
12.2SX
This command is supported in the Cisco IOS Release 12.2SX
train. Support in a specific 12.2SX release of this train depends on your
feature set, platform, and platform hardware.
Usage Guidelines
Use this command to configure your CAR policy on an interface. To
specify multiple policies, enter this command once for each policy.
CAR and DCAR can be configured on an interface or subinterface.
Policing Traffic with CAR
CAR embodies a rate-limiting feature for policing traffic. When
policing traffic with CAR, Cisco recommends the following values for the normal
and extended burst parameters:
normal burst (in bytes) = configured rate (in bits per second) * (1
byte)/(8 bits) * 1.5 seconds
With the listed choices for parameters, extensive test results have
shown CAR to achieve the configured rate. If the burst values are too low, then
the achieved rate is often much lower than the configured rate.
For more information about using CAR to police traffic, see the
“Policing with CAR” section of the “Policing and Shaping Overview” in the
Cisco IOS Quality of Service Solutions Configuration Guide .
Examples
In the following example, the recommended burst parameters for CAR
are used:
In the following example, the rate is limited by the application in
question:
All World Wide Web
traffic is transmitted. However, the MPLS experimental field for web traffic
that conforms to the first rate policy is set to 5. For nonconforming traffic,
the IP precedence is set to 0 (best effort). See the following commands in the
example:
FTP traffic is
transmitted with an MPLS experimental field value of 5 if it conforms to the
second rate policy. If the FTP traffic exceeds the rate policy, it is dropped.
See the following commands in the example:
rate-limit input access-group 102 10000000 24000 32000
conform-action set-mpls-exp-transmit 5 exceed-action drop
access-list 102 permit tcp any any eq ftp
Any remaining traffic is
limited to 8 Mbps, with a normal burst size of 1,500,000 bytes and an excess
burst size of 3,000,000 bytes. Traffic that conforms is sent with an MPLS
experimental field of 5. Traffic that does not conform is dropped. See the
following command in the example:
rate-limit input 8000000 1500000 3000000 conform-action set-mpls-exp-transmit 5
exceed-action drop
Notice that two access lists are created to classify the web and FTP
traffic so that they can be handled separately by the CAR feature.
Router(config)# interface Hssi0/0/0
Router(config-if)# description 45Mbps to R2
Router(config-if)# rate-limit input rate-limit access-group 101 20000000 3750000 7500000conform-action set-mpls-exp-transmit 5 exceed-action set-mpls-exp-transmit 0
Router(config-if)# rate-limit input access-group 102 10000000 1875000 3750000conform-action set-mpls-exp-transmit 5 exceed-action drop
Router(config-if)# rate-limit input 8000000 1500000 3000000 conform-actionset-mpls-exp-transmit 5 exceed-action drop
Router(config-if)# ip address 10.1.1.1 255.255.255.252
!
Router(config-if)# access-list 101 permit tcp any any eq www
Router(config-if)# access-list 102 permit tcp any any eq ftp
In the following example, the MPLS experimental field is set, and the
packet is transmitted:
Configures an access list for use with CAR policies.
showaccess-listsrate-limit
Displays information about rate-limit access lists.
showinterfacesrate-limit
Displays information about CAR for a specified interface.
rcv-queue bandwidth
To define the bandwidths for ingress (receive) WRR queues through scheduling weights in interface configuration command mode, use the
rcv-queuebandwidthcommand. To return to the default settings, use the
no form of this command.
rcv-queuebandwidthweight-1... weight-n
norcv-queuebandwidth
Syntax Description
weight-1...weight-n
WRR weights; valid values are fr om 0 to 255.
Command Default
The defaults are as follows:
QoS enabled--4:255
QoS disabled--255:1
Command Modes
Interface configuration
Command History
Release
Modification
12.2(17a)SX
This command was introduced on the Supervisor Engine 720.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2(50)SY
Support for this command was introduced.
Usage Guidelines
Note
In Cisco IOS Release 12.2(50)SY and later releases, you can enable this command only if either the
platform qos queueing-only command or the
auto qos default command is configured.
This command is not supported on Cisco 7600 series router that are configured with a Supervisor Engine 2.
This command is supported on 2q8t and 8q8t ports only.
You can configure up to seven queue weights.
Examples
This example shows how to allocate a three-to-one bandwidth ratio:
Sets the size ratio between the strict-priority and standard receive queues.
showqueueinginterface
Displays queueing information.
rcv-queue cos-map
To map the class of service (CoS) values to the standard receive-queue drop thresholds, use the
rcv-queuecos-map command in interface configuration mode. To remove the mapping, use the
no form of this command.
Support for this command was introduced on the Supervisor Engine 720.
12.2(17d)SXB
This command was implemented on the Supervisor Engine 2 and integrated into Cisco IOS Release 12.2(17d)SXB.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2(50)SY
Support for this command was introduced.
Usage Guidelines
Note
In Cisco IOS Release 12.2(50)SY and later releases, you can enable this command only if either the
platform qos queueing-only command or the
auto qos default command is configured.
The
cos-n value is defined by the module and port type. When you enter the cos-n value, note that the higher values indicate higher priorities.
Use this command on trusted ports only.
Examples
This example shows how to map the CoS values 0 and 1 to threshold 1 in the standard receive queue:
To set the size ratio between the strict-priority and standard receive queues, use the
rcv-queuequeue-limit command in interface configuration mode. To return to the default settings, use the
no form of this command.
rcv-queuequeue-limitq-limit-1q-limit-2
norcv-queuequeue-limit
Syntax Description
q-limit-1
Standard queue weight; valid values are from 1 and 100 pe rcent.
q-limit-2
Strict-priority queue weight; see the “Usage Guidelines” section for valid values.
Command Default
The defaults are as follows:
80 percent is for low priority.
20 percent is for strict priority.
Command Modes
Interface configuration
Command History
Release
Modification
12.2(14)SX
Support for this command was introduced on the Supervisor Engine 720.
12.2(17d)SXB
This command was implemented on the Supervisor Engine 2 and integrated into Cisco IOS Release 12.2(17d)SXB.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2(50)SY
Support for this command was introduced.
Usage Guidelines
Note
In Cisco IOS Release 12.2(50)SY and later releases, you can enable this command only if either the
platform qos queueing-only command or the
auto qos default command is configured.
Valid strict-priority weight values are fro m 1 to 100 percent, excep t on 1p1q8t ingress LAN ports, where valid values for the strict-priority queue are from 3 to 100 perce nt.
The
rcv-queuequeue-limit command configures ports on a per-ASIC basis.
Estimate the mix of strict-priority-to-standard traffic on your network (for example, 80-percent standard traffic and 20-percent strict-priority traffic) and use the estimated percentages as queue weights.
Examples
This example shows how to set the receive-queue size ratio for Gigabit Ethernet interface 1/2:
To specify the minimum and maximum threshold for the specified receive queues, use the
rcv-queuerandom-detect command in interface configuration mode. To return to the det fault settings, use the
no form of this command.
Threshold weights; valid values are from 1 to 100 percent.
Command Default
The defaults are as follows:
min-threshold -- 80 percent
max-threshold -- 20 percent
Command Modes
Interface configuration
Command History
Release
Modification
12.2(17a)SX
Support for this command was introduced on the Supervisor Engine 720.
12.2(17d)SXB
This command was implemented on the Supervisor Engine 2 and integrated into Cisco IOS Release 12.2(17d)SXB.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2(50)SY
Support for this command was introduced.
Usage Guidelines
Note
In Cisco IOS Release 12.2(50)SY and later releases, you can enable this command only if either the
platform qos queueing-only command or the
auto qos default command is configured.
This command is supported on 1p1q8t and 8q8t ports only.
The 1p1q8t interface indicates one strict queue and one standard queue with eight thresholds. The 8q8t interface indicates eight standard queues with eight thresholds. The threshold in the strict-priority queue is not configurable.
Each threshold has a low- and a high-threshold value. The threshold values are a percentage of the receive-queue capacity.
For additional information on configuring receive-queue thresholds, refer to the "QoS" chapter in the
Cisco 7600 Series Router Cisco IOS Software Configuration Guide.
Examples
This example shows how to configure the low-priority receive-queue thresholds:
To configure the drop-threshold percentages for the standard receive queues on 1p1q4t and 1p1q0t interfaces, use the
rcv-queuethreshold command in interface configuration mode. To return the thresholds to the default settings, use the
no form of this command.
Threshold ID; valid values are from 1 to 100 percent .
Command Default
The defaults for the 1p1q4t and 1p1q0t configurations are as follows:
Quality of service (QoS) assigns all traffic with class of service (CoS) 5 to the strict-priority queue.
QoS assigns all other traffic to the standard queue.
The default for the 1q4t configuration is that QoS assigns all traffic to the standard queue.
If you enable QoS, the following default thresholds apply:
1p1q4t interfaces have this default drop-threshold configuration:
Frames with CoS 0, 1, 2, 3, 4, 6, or 7 go to the standard receive queue.
Using standard receive-queue drop threshold 1, the Cisco 7600 series router drops incoming frames with CoS 0 or 1 when the receive-queue buffer is 50 percent or more full.
Using standard receive-queue drop threshold 2, the Cisco 7600 series router drops incoming frames with CoS 2 or 3 when the receive-queue buffer is 60 percent or more full.
Using standard receive-queue drop threshold 3, the Cisco 7600 series router drops incoming frames with CoS 4 when the receive-queue buffer is 80 percent or more full.
Using standard receive-queue drop threshold 4, the Cisco 7600 series router drops incoming frames with CoS 6 or 7 when the receive-queue buffer is 100 percent full.
Frames with CoS 5 go to the strict-priority receive queue (queue 2), where the Cisco 7600 series router drops incoming frames only when the strict-priority receive-queue buffer is 100 percent full.
1p1q0t interfaces have this default drop-threshold configuration:
Frames with CoS 0, 1, 2, 3, 4, 6, or 7 go to the standard receive queue. The Cisco 7600 series router drops incoming frames when the receive-queue buffer is 100 percent full.
Frames with CoS 5 go to the strict-priority receive queue (queue 2), where the Cisco 7600 series router drops incoming frames only when the strict-priority receive-queue buffer is 100 percent full.
Note
The 100-percent threshold may be actually changed by the module to 98 percent to allow Bridge Protocol Data Unite (BPDU) traffic to proceed. The BPDU threshold is factory set at 100 percent.
Command Modes
Interface configuration
Command History
Release
Modification
12.2(14)SX
Support for this command was introduced on the Supervisor Engine 720.
12.2(17d)SXB
This command was implemented on the Supervisor Engine 2 and integrated into Cisco IOS Release 12.2(17d)SXB.
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2(50)SY
Support for this command was introduced.
Usage Guidelines
Note
In Cisco IOS Release 12.2(50)SY and later releases, you can enable this command only if either the
platform qos queueing-only command or the
auto qos default command is configured.
The
queue-id value is always 1.
A value of 10 indicates a threshold when the buffer is 10 percent full.
Always set threshold 4 to 100 percent.
Receive thresholds take effect only on ports whose trust state is trust cos.
Configure the 1q4t receive-queue tail-drop threshold percentages with the
wrr-queuethresholdcommand.
Examples
This example shows how to configure the receive-queue drop thresholds for Gigabit Ethernet interface 1/1:
Configures the drop-threshold percentages for the standard receive and transmit queues on 1q4t and 2q2t interfaces.
recoverable-loss
To enable Enhanced Compressed Real-Time Transport Protocol (ECRTP), use the recoverable-loss command in IPHC-profile configuration mode. To disable ECRTP, use the no form of this command.
recoverable-loss
{ dynamic | packet-drops }
norecoverable-loss
Syntax Description
dynamic
Indicates that the dynamic recoverable loss calculation is used.
packet-drops
Maximum number of consecutive packet drops. Range is from 1 to 8.
Command Default
ECRTP is disabled.
Command Modes
IPHC-profile configuration (config-iphcp)
Command History
Release
Modification
12.4(9)T
This command was introduced.
12.4(11)T
Support was added for Frame Relay encapsulation.
Usage Guidelines
The recoverable-loss command is part of the ECRTP feature.
ECRPT Functionality
ECRTP reduces corruption by managing the way the compressor updates the context information at the decompressor. The compressor sends updated context information periodically to keep the compressor and decompressor synchronized. By repeating the updates, the probability of context corruption because of packet loss is minimized.
The synchronization of context information between the compressor and the decompressor can be performed dynamically (by specifying the dynamic keyword) or whenever a specific number of packets are dropped (by using the packet-dropsargument).
The number of packet drops represents the quality of the link between the hosts. The lower the number of packet drops, the higher the quality of the link between the hosts.
The packet drops value is maintained independently for each context and does not have to be the same for all contexts.
Note
If you specify the number of packet drops with the packet-drops argument, the recoverable-losscommand automatically enables ECRTP.
Intended for Use with IPHC Profiles
The recoverable-losscommand is intended for use as part of an IP Header Compression (IPHC) profile. An IPHC profile is used to enable and configure header compression on a network. For more information about using IPHC profiles to configure header compression, see the “Header Compression” module and the “Configuring Header Compression Using IPHC Profiles” module of the Cisco IOS Quality of Service Solutions Configuration Guide
, Release 12.4T.
Examples
The following example shows how to configure an IPHC profile called profile2. In this example, ECRTP is enabled with a maximum number of five consecutive packet drops.
To configure a traffic class to redirect packets belonging to a specific class to the interface that is specified in the command, use the redirect interface command in policy-map class configuration mode. To prevent the packets from getting redirected, use the no form of this command
redirectinterfaceinterfacetypenumber
noredirectinterfaceinterfacetypenumber
Syntax Description
interfacetypenumber
The type and number of the interface to which the packets need to be redirected.
Command Default
If this command is not specified, the packets are not redirected to an interface
Command Modes
Policy-map class configuration (config-pmap-c)
Command History
Release
Modification
12.2(18)ZYA1
This command was introduced.
Usage Guidelines
Use this command to redirect packets to a predefined interface. You can also configure the redirect interface command with the log command but not with a drop or copy interface command. This command cannot be configured with a service policy for a stack class. The packets can be redirected only to the following interfaces:
Ethernet
Fast Ethernet
Gigabit Ethernet
Ten Gigabit Ethernet
Examples
In the following example, a traffic class called cmtest has been created and configured for use in a policy map called pmtest. The policy map (service policy) is attached to Fast Ethernet interface 4/15. All packets in the cmtest are redirected to FastEthernet interface 4/18.
Generates a log of messages in the policy-map class configuration mode or class-map configuration mode.
showclass-map
Displays all class maps and their matching criteria.
showpolicy-map
Displays the configuration of all classes for a specified service policy map or all classes for all existing policy maps.
showpolicy-mapinterface
Displays the packet statistics of all classes that are configured for all service policies either on the specified interface or subinterface or on a specific PVC on the interface.
refresh max-period
To set the number of packets sent between full-header refresh occurrences, use the refreshmax-periodcommand in IPHC-profile configuration mode. To use the default number of packets, use the no form of this command.
Number of packets sent between full-header refresh occurrences. Range is from 0 to 65535. Default is 256.
infinite
Indicates no limitation on the number of packets sent between full-header refresh occurrences.
Command Default
The number of packets sent between full-header refresh occurrences is 256.
Command Modes
IPHC-profile configuration
Command History
Release
Modification
12.4(9)T
This command was introduced.
Usage Guidelines
Use the refreshmax-period command to set the number of non-TCP packets sent between full-header refresh occurrences. The refreshmax-period command also allows you to specify no limitation on the number of packets sent between full-header refresh occurrences. To specify no limitation on the number of packets sent, use the infinite keyword.
Prerequisite
Before you use the refreshmax-periodcommand, you must enable non-TCP header compression by using thenon-tcp command.
Intended for Use with IPHC Profiles
The refreshmax-periodcommand is intended for use as part of an IPHC profile. An IPHC profile is used to enable and configure header compression on your network. For more information about using IPHC profiles to configure header compression, see the “Header Compression” module and the “Configuring Header Compression Using IPHC Profiles” module of the Cisco IOS Quality of Service Solutions Configuration Guide
, Release 12.4T.
Examples
The following is an example of an IPHC profile called profile2. In this example, the number of packets sent before a full-header refresh occurrence is 700 packets.
Enables non-TCP header compression within an IPHC profile.
refresh max-time
To set the amount of time to wait before a full-header refresh occurrence, use the refreshmax-timecommand in IPHC-profile configuration mode. To use the default time, use the no form of this command.
refreshmax-time
{ seconds | infinite }
norefreshmax-time
Syntax Description
seconds
Length of time, in seconds, to wait before a full-header refresh occurrence. Range is from 0 to 65535. Default is 5.
infinite
Indicates no limitation on the time between full-header refreshes.
Command Default
The amount of time to wait before a full-header refresh occurrence is set to 5 seconds.
Command Modes
IPHC-profile configuration
Command History
Release
Modification
12.4(9)T
This command was introduced.
Usage Guidelines
Use the refreshmax-timecommand to set the maximum amount of time to wait before a full-header refresh occurs. The refreshmax-time command also allows you to indicate no limitation on the time between full-header refresh occurrences. To specify no limitation on the time between full-header refresh occurrences, use the infinite keyword.
Prerequisite
Before you use the refreshmax-time command, you must enable non-TCP header compression by using the non-tcp command.
Intended for Use with IPHC Profiles
The refreshmax-timecommand is intended for use as part of an IPHC profile. An IPHC profile is used to enable and configure header compression on your network. For more information about using IPHC profiles to configure header compression, see the “Header Compression” module and the “Configuring Header Compression Using IPHC Profiles” module of the Cisco IOS Quality of Service Solutions Configuration Guide
, Release 12.4T.
Examples
The following is an example of an IPHC profile called profile2. In this example, the maximum amount of time to wait before a full-header refresh occurs is 500 seconds.
Enables non-TCP header compression within an IPHC profile.
refresh rtp
To enable a context refresh occurrence for Real-Time Transport Protocol (RTP) header compression, use the refreshrtp command in IPHC-profile configuration mode. To disable a context refresh occurrence for RTP header compression, use the no form of this command.
refreshrtp
norefreshrtp
Syntax Description
This command has no arguments or keywords.
Command Default
Context refresh occurrences for RTP header compression are disabled.
Command Modes
IPHC-profile configuration
Command History
Release
Modification
12.4(9)T
This command was introduced.
Usage Guidelines
Use the refreshrtp command to enable a context refresh occurrence for RTP header compression. A context is the state that the compressor uses to compress a header and that the decompressor uses to decompress a header. The context is the uncompressed version of the last header sent and includes information used to compress and decompress the packet.
Prerequisite
Before you use the refreshrtpcommand, you must enable RTP header compression by using the rtpcommand.
Intended for Use with IPHC Profiles
The refreshrtpcommand is intended for use as part of an IP header compression (IPHC) profile. An IPHC profile is used to enable and configure header compression on your network. For more information about using IPHC profiles to configure header compression, see the “Header Compression” module and the “Configuring Header Compression Using IPHC Profiles” module of the Cisco IOS Quality of Service Solutions Configuration Guide
, Release 12.4T.
Examples
The following is an example of an IPHC profile called profile2. In this example, the refreshrtp command is used to enable a context refresh occurrence for RTP header compression.
Enables RTP header compression within an IPHC profile.
rtp
To enable Real-Time Transport Protocol (RTP) header compression within an IP Header Compression (IPHC) profile, use the
rtp command in IPHC-profile configuration mode. To disable RTP header compression within an IPHC profile, use the
no form of this command.
rtp
nortp
Syntax Description
This command has no arguments or keywords.
Command Default
RTP header compression is enabled.
Command Modes
IPHC-profile configuration
Command History
Release
Modification
12.4(9)T
This command was introduced.
Usage Guidelines
The
rtp command enables RTP header compression and automatically enables non-TCP header compression (the equivalent of using the
non-tcp command).
Intended for Use with IPHC Profiles
The
rtpcommand is intended for use as part of an IP Header Compression (IPHC) profile. An IPHC profile is used to enable and configure header compression on a network. For more information about using IPHC profiles to configure header compression, see the “Header Compression” module and the “Configuring Header Compression Using IPHC Profiles” module of the
Cisco IOS Quality of Service Solutions Configuration Guide, Release 12.4T.
Examples
The following example shows how to configure an IPHC profile called profile2. In this example, RTP header compression is configured.