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Cisco IOS Quality of Service Solutions Command Reference, Release 12.2
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About Cisco IOS Software Documentation
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Using Cisco IOS Software
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Commands: access-list rate-limit -- fair-queue (WFQ)
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Commands: fair-queue aggregate-limit -- ip nbar pdlm
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Commands: ip nbar port-map -- ip rsvp reservation
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Commands: ip rsvp reservation-host -- match ip dscp
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Commands: match ip precedence -- police
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Commands: policy-map -- qos pre-classify
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Commands: queue-limit -- random-detect precedence
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Commands: rate-limit -- set qos-group
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Commands: shape -- show ip nbar pdlm
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Commands: show ip nbar port-map -- show qdm status
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Commands: show queue -- vc-hold-queue
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Feedback
Table Of Contents
policy-map
To create or modify a policy map that can be attached to one or more interfaces to specify a service policy, use the policy-map global configuration command. To delete a policy map, use the no form of this command.
policy-map policy-map-name
no policy-map policy-map-name
Syntax Description
Defaults
This command has no default behavior or values.
Command Modes
Global configuration
Command History
Usage Guidelines
Use the policy-map command to specify the name of the policy map to be created, added to, or modified before you can configure policies for classes whose match criteria are defined in a class map. Entering the policy-map command enables QoS policy-map configuration mode in which you can configure or modify the class policies for that policy map.
You can configure class policies in a policy map only if the classes have match criteria defined for them. You use the class-map and match commands to configure the match criteria for a class. Because you can configure a maximum of 64 class maps, no policy map can contain more than 64 class policies.
A single policy map can be attached to multiple interfaces concurrently. When you attempt to attach a policy map to an interface, the attempt is denied if the available bandwidth on the interface cannot accommodate the total bandwidth requested by class policies comprising the policy map. In this case, if the policy map is already attached to other interfaces, it is removed from them.
Whenever you modify class policy in an attached policy map, CBWFQ is notified and the new classes are installed as part of the policy map in the CBWFQ system.
Examples
The following example creates a policy map called policy1 and configures two class policies included in that policy map. The class policy called class1 specifies policy for traffic that matches access control list (ACL) 136. The second class is the default class to which packets that do not satisfy configured match criteria are directed.
! The following commands create class-map class1 and defines its match criteria:class-map class1match access-group 136! The following commands create the policy map, which is defined to contain policy! specification for class1 and the default class:policy-map policy1class class1bandwidth 2000queue-limit 40class class-defaultfair-queue 16queue-limit 20The following example creates a policy map called policy9 and configures three class policies to belong to that map. Of these classes, two specify policy for classes with class maps that specify match criteria based on either a numbered ACL or an interface name, and one specifies policy for the default class called class-default to which packets that do not satisfy configured match criteria are directed.
policy-map policy9class acl136bandwidth 2000queue-limit 40class ethernet101bandwidth 3000random-detect exponential-weighting-constant 10class class-default fair-queue 10queue-limit 20Related CommandsRelated Commands
precedence (VC bundle)
To configure precedence levels for a virtual circuit (VC) class that can be assigned to a VC bundle and thus applied to all VC members of that bundle, use the precedence vc-class configuration command. To remove the precedence levels from the VC class, use the no form of this command.
To configure the precedence levels for a VC member of a bundle, use the precedence bundle-vc configuration command. To remove the precedence levels from the VC, use the no form of this command.
precedence [other | range]
no precedence
Syntax Description
Defaults
Defaults to other, that is, any precedence levels in the range from 0 to 7 that are not explicitly configured.
Command Modes
VC-class configuration (for a VC class)
Bundle-vc configuration (for ATM VC bundle members)
Command History
Usage Guidelines
Assignment of precedence levels to VC bundle members allows you to create differentiated service because you can distribute the IP Precedence levels over the different VC bundle members. You can map a single precedence level or a range of levels to each discrete VC in the bundle, thereby enabling VCs in the bundle to carry packets marked with different precedence levels. Alternatively, you can configure a VC with the precedence other command to indicate that it can carry traffic marked with precedence levels not specifically configured for it. Only one VC in the bundle can be configured with the precedence other command to carry all precedence levels not specified. This VC is considered the default one.
To use this command in vc-class configuration mode, enter the vc-class atm global configuration command before you enter this command. This command has no effect if the VC class that contains the command is attached to a standalone VC, that is, if the VC is not a bundle member.
To use this command to configure an individual bundle member in bundle-vc configuration mode, first enter the bundle command to enact bundle configuration mode for the bundle to which you want to add or modify the VC member to be configured. Then, use the pvc-bundle command to specify the VC to be created or modified and enter bundle-vc configuration mode.
VCs in a VC bundle are subject to the following configuration inheritance guidelines (listed in order of next highest precedence):
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VC configuration in bundle-vc mode
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Examples
The following example configures a class called control-class that includes a precedence command that, when applied to a bundle, configures all VC members of that bundle to carry IP Precedence level 7 traffic. Note, however, that VC members of that bundle can be individually configured with the precedence command at the bundle-vc level, which would supervene.
vc-class atm control-classprecedence 7The following example configures permanent virtual circuit (PVC) 401 (with the name of control-class) to carry traffic with IP Precedence levels in the range of 4-2, overriding the precedence level mapping set for the VC through vc-class configuration:
pvc-bundle control-class 401precedence 4-2Related Commands
precedence (WRED group)
To configure a Weighted Random Early Detection (WRED) or VIP-distributed WRED (DWRED) group for a particular IP Precedence, use the precedence random-detect-group configuration command. To return the values for each IP Precedence for the group to the default values, use the no form of this command.
precedence precedence min-threshold max-threshold mark-probability-denominator
no precedence precedence min-threshold max-threshold mark-probability-denominator
Syntax Description
Defaults
For all IP Precedences, the mark-probability-denominator argument is 10, and the max-threshold argument is based on the output buffering capacity and the transmission speed for the interface.
The default min-threshold argument depends on the IP Precedence. The min-threshold argument for IP Precedence 0 corresponds to half of the max-threshold argument. The values for the remaining IP Precedences fall between half the max-threshold argument and the max-threshold argument at evenly spaced intervals. See Table 9 in the "Usage Guidelines" section of this command for a list of the default minimum value for each IP Precedence.
Command Modes
Random-detect-group configuration
Command History
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).
If used, this command is issued after the random-detect-group command.
When you configure the random-detect group command on an interface, packets are given preferential treatment based on the IP Precedence of the packet. Use the precedence command to adjust the treatment for different IP Precedences.
If you want WRED or DWRED to ignore the IP Precedence when determining which packets to drop, enter this command with the same parameters for each IP Precedence. Remember to use reasonable values for the minimum and maximum thresholds.
Note
Table 9 lists the default minimum value for each IP Precedence.
Table 9 Default WRED Minimum Threshold Values
(Fraction of Maximum Threshold Value)0
8/16
1
9/16
2
10/16
3
11/16
4
12/16
5
13/16
6
14/16
7
15/16
Examples
The following example specifies parameters for the WRED parameter group called sanjose for the different IP Precedences:
random-detect-group sanjoseprecedence 0 32 256 100precedence 1 64 256 100precedence 2 96 256 100precedence 3 128 256 100precedence 4 160 256 100precedence 5 192 256 100precedence 6 224 256 100precedence 7 256 256 100Related Commands
priority
To give priority to a class of traffic belonging to a policy map, use the priority policy-map class configuration command. To remove a previously specified priority specified for a class, use the no form of this command.
priority bandwidth-kbps [burst]
no priority bandwidth-kbps [burst]
Syntax Description
Defaults
This command has no default behavior or values.
Command Modes
Policy-map class configuration
Command History
Usage Guidelines
This command configures low latency queueing (LLQ), providing strict priority queueing (PQ) for class-based weighted fair queueing (CBWFQ). Strict PQ allows delay-sensitive data such as voice to be dequeued and sent before packets in other queues are dequeued.
The priority command allows you to set up classes based on a variety of criteria (not just User Datagram Ports (UDP) ports) and assign priority to them, and is available for use on serial interfaces and ATM permanent virtual circuits (PVCs). A similar command, ip rtp priority, allows you to stipulate priority flows based only on UDP port numbers and is not available for ATM PVCs.
When the device is not congested, the priority class traffic is allowed to exceed its allocated bandwidth. When the device is congested, the priority class traffic above the allocated bandwidth is discarded.
The burst argument is used to specify the burst size and, therefore, configure the network to accommodate temporary bursts of traffic. The default burst value, which is computed as 200 milliseconds of traffic at the configured bandwidth rate, is used when the burst argument is not specified.
The bandwidth and priority commands cannot be used in the same class, within the same policy map. These commands can be used together in the same policy map, however.
Within a policy map, you can give one or more classes priority status. When multiple classes within a single policy map are configured as priority classes, all traffic from these classes is queued to the same, single, priority queue.
Remember the following guidelines when using the priority command:
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•
•
•
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policy-map policy1class voice1priority 24class voice2priority 48class databandwidth 20In this example, voice1 and voice2 classes of traffic go into the high priority queue and get priority queueing over data traffic. However, voice1 traffic will be rate-limited to 24 kbps and voice2 traffic will be rate-limited to 48 kbps.
Examples
The following example configures PQ with a guaranteed bandwidth of 50 kbps and a one-time allowable burst size of 60 bytes for the policy map called policy1:
Router(config)# policy-map policy1Router(config-pmap)# class voiceRouter(config-pmap-c)# priority 50 60In the following example, 10 percent of the available bandwidth is reserved for the class called voice on interfaces that have attached the policy map called policy1:
Router(config)# policy-map policy1Router(config-pmap)# class voiceRouter(config-pmap-c)# priority percent 10Related Commands
priority-group
To assign the specified priority list to an interface, use the priority-group interface configuration command. To remove the specified priority group assignment, use the no form of this command.
priority-group list-number
no priority-group list-number
Syntax Description
Defaults
This command is disabled by default.
Command Modes
Interface configuration
Command History
Usage Guidelines
Only one list can be assigned per interface. Priority output queueing provides a mechanism to prioritize packets sent on an interface.
Use the show queueing and show interfaces commands to display the current status of the output queues.
Examples
The following example causes packets for transmission on serial interface 0 to be classified by priority list 1:
interface serial 0priority-group 1The following example shows how to establish queueing priorities based on the address of the serial link on a serial tunnel (STUN) connection. Note that you must use the priority-group interface configuration command to assign a priority group to an output interface.
stun peer-name 131.108.254.6stun protocol-group 1 sdlc!interface serial 0! Disable the ip address for interface serial 0:no ip address! Enable the interface for STUN:encapsulation stun!stun group 2stun route address 10 tcp 131.108.254.8 local-ack priority!! Assign priority group 1 to the input side of interface serial 0:priority-group 1! Assign a low priority to priority list 1 on serial link identified! by group 2 and address A7:priority-list 1 stun low address 2 A7Related Commands
priority-list default
To assign a priority queue for those packets that do not match any other rule in the priority list, use the priority-list default global configuration command. To return to the default or assign normal as the default, use the no form of this command.
priority-list list-number default {high | medium | normal | low}
no priority-list list-number default
Syntax Description
list-number
Any number from 1 to 16 that identifies the priority list.
high | medium | normal | low
Priority queue level. The normal queue is used if you use the no form of this command.
Defaults
This command is not enabled by default.
Command Modes
Global configuration
Command History
Usage Guidelines
When you use multiple rules, remember that the system reads the priority settings in order of appearance. When classifying a packet, the system searches the list of rules specified by priority-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.
Examples
The following example sets the priority queue for those packets that do not match any other rule in the priority list to a low priority:
priority-list 1 default lowRelated Commands
priority-list interface
To establish queueing priorities on packets entering from a given interface, use the priority-list interface global configuration command. To remove an entry from the list, use the no form of this command with the appropriate arguments.
priority-list list-number interface interface-type interface-number {high | medium | normal | low}
no priority-list list-number interface interface-type interface-number {high | medium | normal | low}
Syntax Description
Defaults
No queueing priorities are established by default.
Command Modes
Global configuration
Command History
Usage Guidelines
When you use multiple rules, remember that the system reads the priority settings in order of appearance. When classifying a packet, the system searches the list of rules specified by priority-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.
Examples
The following example assigns a list entering on serial interface 0 to a medium priority queue level:
priority-list 3 interface serial 0 medium
Note
Related Commands
priority-list protocol
To establish queueing priorities based upon the protocol type, use the priority-list protocol global configuration command. To remove a priority list entry assigned by protocol type, use the no form of this command with the appropriate arguments.
priority-list list-number protocol protocol-name {high | medium | normal | low} queue-keyword keyword-value
no priority-list list-number protocol [protocol-name {high | medium | normal | low} queue-keyword keyword-value]
Syntax Description
Defaults
No queueing priorities are established.
Command Modes
Global configuration
Command History
Usage Guidelines
When you use multiple rules for a single protocol, remember that the system reads the priority settings in order of appearance. When classifying a packet, the system searches the list of rules specified by priority-list commands for a matching protocol 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.
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 stun keywords refer only to direct encapsulation.
Use Table 10, Table 11, and Table 12 to configure the queueing priorities for your system.
Table 10 Protocol Priority Queue Keywords and Values
fragments
Assigns the priority level defined to fragmented IP packets (for use with IP only). More specifically, this command matches IP packets whose fragment offset field is nonzero. The initial fragment of a fragmented IP packet has a fragment offset of zero, so such packets are not matched by this command.
Note
gt byte-count
Specifies a greater-than count. The priority level assigned goes into effect when a packet size exceeds the value entered for the byte-count argument.
Note
list list-number
Assigns traffic priorities according to a specified list when used with AppleTalk, bridging, IP, IPX, VINES, or XNS. The list-number argument is the access list number as specified by the access-list global configuration command for the specified protocol-name. For example, if the protocol is AppleTalk, list-number should be a valid AppleTalk access list number.
lt byte-count
Specifies a less-than count. The priority level assigned goes into effect when a packet size is less than the value entered for the byte-count argument.
Note
tcp port
Assigns the priority level defined to TCP segments originating from or destined to a specified port (for use with IP only). Table 11 lists common TCP services and their port numbers.
udp port
Assigns the priority level defined to UDP packets originating from or destined to a specified port (for use with IP only). Table 12 lists common UDP services and their port numbers.
Table 11 Common TCP Services and Their Port Numbers
FTP data
20
FTP
21
Simple Mail Transfer Protocol (SMTP)
25
Telnet
23
Table 12 Common UDP Services and Their Port Numbers
Domain Name System (DNS)
53
Network File System (NFS)
2049
remote-procedure call (RPC)
111
SNMP
161
TFTP
69
Note
For some protocols, such as TFTP and FTP, only the initial request uses port 69. Subsequent packets use a randomly chosen port number. For these types of protocols, the use of port numbers fails to be an effective method to manage queued traffic.Examples
The following example assigns 1 as the arbitrary priority list number, specifies DECnet as the protocol type, and assigns a high-priority level to the DECnet packets sent on this interface:
priority-list 1 protocol decnet highThe following example assigns a medium-priority level to every DECnet packet with a size greater than 200 bytes:
priority-list 2 protocol decnet medium gt 200The following example assigns a medium-priority level to every DECnet packet with a size less than 200 bytes:
priority-list 4 protocol decnet medium lt 200The following example assigns a high-priority level to traffic that matches IP access list 10:
priority-list 1 protocol ip high list 10The following example assigns a medium-priority level to Telnet packets:
priority-list 4 protocol ip medium tcp 23The following example assigns a medium-priority level to UDP DNS packets:
priority-list 4 protocol ip medium udp 53The following example assigns a high-priority level to traffic that matches Ethernet type code access list 201:
priority-list 1 protocol bridge high list 201The following example assigns a high-priority level to data-link switching plus (DLSw+) traffic with TCP encapsulation:
priority-list 1 protocol ip high tcp 2065The following example assigns a high-priority level to DLSw+ traffic with direct encapsulation:
priority-list 1 protocol dlsw high
Note
Related Commands
priority-list queue-limit
To specify the maximum number of packets that can be waiting in each of the priority queues, use the priority-list queue-limit global configuration command. To select the normal queue, use the no form of this command.
priority-list list-number queue-limit [high-limit [medium-limit [normal-limit [low-limit]]]]
no priority-list list-number queue-limit
Syntax Description
Defaults
This command is not enabled by default.
See Table 13 in the "Usage Guidelines" section of this command for a list of the default queue limit arguments.
Command Modes
Global configuration
Command History
Usage Guidelines
If a priority queue overflows, excess packets are discarded and messages can be sent, if appropriate, for the protocol.
The default queue limit arguments are listed in Table 13.
Table 13 Default Priority Queue Packet Limits
high-limit
20
medium-limit
40
normal-limit
60
low-limit
80
Note
Examples
The following example sets the maximum packets in the priority queue to 10:
priority-list 2 queue-limit 10 40 60 80Related Commands
protect
To configure a virtual circuit (VC) class with protected group or protected VC status for application to a VC bundle member, use the protect command in vc-class configuration mode. To remove the protected status from the VC class, use the no form of this command.
To configure a specific VC as part of a protected group of the bundle or to configure it as an individually protected VC bundle member, use the protect command in bundle-vc configuration mode. To remove the protected status from the VC, use the no form of this command.
protect {group | vc}
no protect {group | vc}
Syntax Description
group
Configures the VC bundle member as part of the protected group of the bundle.
vc
Configures the VC member as individually protected.
Defaults
The VC neither belongs to the protected group nor is it an individually protected VC.
Command Modes
VC-class configuration (for a VC class)
Bundle-vc configuration (for ATM VC bundle members)
Command History
Usage Guidelines
Use this command in vc-class configuration mode to configure a VC class to contain protected group or individual protected VC status. When the class is applied to the VC bundle member, that VC is characterized by the protected status. You can also apply this command directly to a VC in bundle-vc configuration mode.
When a protected VC goes down, it takes the bundle down. When all members of a protected group go down, the bundle goes down.
To use this command in vc-class configuration mode, first enter the vc-class atm global configuration command.
This command has no effect if the VC class that contains the command is attached to a standalone VC, that is, if the VC is not a bundle member.
To use this command in bundle-vc configuration mode, first enter the bundle command to enact bundle configuration mode for the bundle containing the VC member to be configured. Then enter the pvc-bundle configuration command to add the VC to the bundle as a member of it.
VCs in a VC bundle are subject to the following configuration inheritance guidelines (listed in order of next highest precedence):
•
•
•
Examples
The following example configures a class called control-class to include a protect command, which, when applied to a VC bundle member, configures the VC as an individually protected VC bundle member. When this protected VC goes down, it takes the bundle down.
vc-class atm control-classprotect vcRelated Commands
pvc-bundle
To add a virtual circuit (VC) to a bundle as a member of the bundle and enter bundle-vc configuration mode in order to configure that VC bundle member, use the pvc-bundle bundle configuration command. To remove the VC from the bundle, use the no form of this command.
pvc-bundle pvc-name [vpi/] [vci]
no pvc-bundle pvc-name [vpi/] [vci]
Syntax Description
Defaults
This command has no default behavior or values.
Command Modes
Bundle configuration
Command History
Usage Guidelines
Each bundle can contain multiple VCs having different QoS attributes. This command associates a VC with a bundle, making it a member of that bundle. Before you can add a VC to a bundle, the bundle must exist. Use the bundle command to create a bundle. You can also use this command to configure a VC that already belongs to a bundle. You enter the command in the same way, giving the name of the VC bundle member.
The pvc-bundle command enters bundle-vc configuration mode, in which you can specify VC-specific and VC class attributes for the VC.
Examples
The following example specifies an existing bundle called chicago and enters bundle configuration mode. Then it adds two VCs to the bundle. For each added VC, bundle-vc mode is entered and a VC class is attached to the VC to configure it.
bundle chicago pvc-bundle chicago-control 207 class control-class pvc-bundle chicago-premium 206 class premium-classThe following example configures the PVC called chicago-control, an existing member of the bundle called chicago, to use class-based weighted fair queueing (CBWFQ). The example configuration attaches the policy map called policy1 to the PVC. Once the policy map is attached, the classes comprising policy1 determine the service policy for the PVC chicago-control.
bundle chicago pvc-bundle chicago-control 207 class control-class service-policy output policy1Related Commands
qos pre-classify
To enable QoS preclassification, use the qos pre-classify interface configuration command. To disable the QoS preclassification feature, use the no form of this command.
qos pre-classify
no qos pre-classify
Syntax Description
This command has no arguments or keywords.
Defaults
This command is disabled by default.
Command Modes
Interface configuration
Command History
12.0(5)XE3
This command was introduced.
12.1(5)T
This command was integrated into Cisco IOS Release 12.1(5)T.
Usage Guidelines
This command is restricted to tunnel interfaces, virtual templates, and crypto maps. The qos pre-classify command is unavailable on all other interface types.
The qos pre-classify command can be enabled for IP packets only.
Examples
The following example enables the QoS for Virtual Private Networks (VPNs) feature on tunnel interfaces and virtual templates:
Router(config-if)# qos pre-classifyThe following example enables the QoS for VPNs feature on crypto maps:
Router(config-crypto-map)# qos pre-classifyRelated Commands
show interfaces
Displays the statistical information specific to a serial interface.
show queue
Displays the contents of packets inside a queue for a particular interface or VC.
