- Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols, Release 12.2
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Table Of Contents
distribute-list in (RIP, IGRP, EIGRP)
distribute-list out (RIP, IGRP, EIGRP)
IGRP Commands
Use the commands in this chapter to configure and monitor Interior Gateway Routing Protocol (IGRP). For IGRP configuration information and examples, refer to the "Configuring IGRP" chapter of the Cisco IOS IP Configuration Guide.
default-metric (IGRP)
To set metrics for IGRP or Enhanced IGRP (EIGRP), use the default-metric command in router configuration mode. To remove the metric value and restore the default state, use the no form of this command.
default-metric bandwidth delay reliability loading mtu
no default-metric bandwidth delay reliability loading mtu
Syntax Description
Defaults
Only connected routes and interface static routes can be redistributed without a default metric.
Command Modes
Router configuration
Command History
Usage Guidelines
A default metric is required to redistribute a protocol into IGRP or EIGRP, unless you use the redistribute command. Automatic metric translations occur between IGRP and EIGRP. You do not need default metrics to redistribute IGRP or EIGRP into itself.
Note
The default metric command does not affect EIGRP-to-EIGRP or IGRP-to-EIGRP distribution. To configure EIGRP-to-EIGRP or IGRP-to-EIGRP distribution, use route maps.
Metric defaults have been carefully set to work for a wide variety of networks. Take great carewhen changing these values.
Keeping the same metrics is supported only when redistributing from IGRP, EIGRP, or static routes.
Examples
The following example takes redistributed Routing Information Protocol (RIP) metrics and translates them into IGRP metrics with values as follows: bandwidth = 1000, delay = 100, reliability = 250, loading = 100, and MTU = 1500.
router igrp 109network 172.16.0.0redistribute ripdefault-metric 1000 100 250 100 1500Related Commands
redistribute (IP)
Redistributes routes from one routing domain into another routing domain.
distribute-list in (RIP, IGRP, EIGRP)
To filter networks received in updates, use the distribute-list in command in address family or router configuration mode. To disable this function, use the no form of this command.
distribute-list {access-list-number | prefix prefix-list-name [gateway prefix-list-name]} in [interface-type interface-number]
no distribute-list {access-list-number | prefix prefix-list-name [gateway prefix-list-name]} in [interface-type interface-number]
Syntax Description
Defaults
This command is disabled by default.
Command Modes
Address family configuration
Router configuration
Command History
Usage Guidelines
This command is not supported in Intermediate Sytem-to-Intermediate System (IS-IS) or Open Shortest Path First (OSPF).
Using a prefix list allows filtering based upon the prefix length, making it possible to filter either on the prefix list, the gateway, or both for incoming updates.
Specify either an access list or a prefix list with the distribute-list in command.
Use the gateway keyword only with the prefix-list keyword.
To suppress networks from being advertised in updates, use the distribute-list out command.
Examples
In the following example, the BGP routing process accepts only two networks—network 0.0.0.0 and network 192.168.0.0:
access-list 1 permit 0.0.0.0access-list 1 permit 192.168.0.0access-list 1 deny 0.0.0.0 255.255.255.255router bgpnetwork 192.168.0.0distribute-list 1 inIn the following example, The RIP process accepts only prefixes with prefix lengths of /8 to /24:
ip prefix-list max24 seq 5 permit 0.0.0.0/0 ge 8 le 24router ripnetwork 192.168.0.0distribute-list prefix max24 inIn the following example, the RIP process filters on packet length and accepts routing updates from address 192.168.1.1 only:
ip prefix-list max24 seq 5 permit 0.0.0.0/0 ge 8 le 24ip prefix-list allowlist seq5 permit 192.168.1.1/32router ripnetwork 10.108.0.0distribute-list prefix max24 gateway allowlist inRelated Commands
distribute-list out (RIP, IGRP, EIGRP)
To suppress networks from being advertised in updates, use the distribute-list out command in address family or router configuration mode. To disable this function, use the no form of this command.
distribute-list {access-list-number | prefix prefix-list-name [gateway prefix-list-name]} out [interface-name | routing-process | as-number]
no distribute-list {access-list-number | prefix prefix-list-name [gateway prefix-list-name]} out [interface-name | routing-process | as-number]
Syntax Description
Defaults
This command is disabled by default.
Command Modes
Address family configuration
Router configuration
Command History
Usage Guidelines
When redistributing networks, a routing process name can be specified as an optional trailing argument to the distribute-list command. Specifying an argument causes the access list or prefix list to be applied to only those routes derived from the specified routing process. After the process-specific access list or prefix list is applied, any access list or prefix list specified by a distribute-list command without a process name argument will be applied. Addresses not specified in the distribute-list command will not be advertised in outgoing routing updates.
Specify either an access list or a prefix list with the distribute-list in command.
Use the gateway keyword only with the prefix-list keyword.
Note
Examples
The following example causes only one network (network 192.168.0.0) to be advertised by a RIP routing process:
access-list 1 permit 192.168.0.0access-list 1 deny 0.0.0.0 255.255.255.255router ripnetwork 192.168.0.0distribute-list 1 outRelated Commands
ip split-horizon (IGRP)
To enable the split horizon mechanism, use the ip split-horizon command in interface configuration mode. To disable the split horizon mechanism, use the no form of this command.
ip split-horizon
no ip split-horizon
Syntax Description
This command has no arguments or keywords.
Defaults
Default behavior varies with media type.
Command Modes
Interface configuration
Command History
Usage Guidelines
For all interfaces except those for which either Frame Relay or Switched Multimegabit Data Service (SMDS) encapsulation is enabled, the default condition for this command is ip split-horizon; in other words, the split horizon feature is active. If the interface configuration includes either the encapsulation frame-relay or encapsulation smds command, then the default is for split horizon to be disabled. Split horizon is not disabled by default for interfaces using any of the X.25 encapsulations.
Note
Note
Note
Examples
The following simple example disables split horizon on a serial link. The serial link is connected to an X.25 network.
interface serial 0encapsulation x25no ip split-horizonRelated Commands
network (IGRP)
Specifies a list of networks for the IGRP or EIGRP routing process.
metric holddown
To keep new Interior Gateway Routing Protocol (IGRP) routing information from being used for a certain period of time, use the metric holddown command in router configuration mode. To disable this feature, use the no form of this command.
metric holddown
no metric holddown
Syntax Description
This command has no arguments or keywords.
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
Usage Guidelines
The holddown state keeps new routing information from being used for a certain period of time. This function can prevent routing loops caused by slow convergence. It is sometimes advantageous to disable the holddown state to increase the ability of the network to quickly respond to topology changes; this command provides this function.
Use the metric holddown command if other routers or access servers within the IGRP autonomous system are not configured with the no metric holddown command. If all routers are not configured the same way, you increase the possibility of routing loops being created.
Examples
The following example disables metric holddown:
router igrp 15network 10.108.0.0network 192.168.7.0no metric holddownRelated Commands
metric maximum-hops
To have the IP routing software advertise as unreachable those routes with a hop count higher than is specified by the command (Interior Gateway Routing Protocol [IGRP] only), use the metric maximum-hops command in router configuration mode. To reset the value to the default, use the no form of this command.
metric maximum-hops hops-number
no metric maximum-hops hops-number
Syntax Description
hops-number
Maximum hop count (in decimal). The default value is 100 hops; the maximum number of hops that can be specified is 255.
Defaults
100 hops
Command Modes
Router configuration
Command History
Usage Guidelines
This command provides a safety mechanism that breaks any potential count-to-infinity problems. It causes the IP routing software to advertise as unreachable routes with a hop count greater than the value assigned to the hops-number argument.
Examples
In the following example, a router in autonomous system 71 attached to network 10.0.0.0 wants a maximum hop count of 200, doubling the default. The network administrators configured the router hop count to 200 because they have a complex WAN that can generate a large hop count under normal (nonlooping) operations.
router igrp 71network 10.0.0.0metric maximum-hops 200Related Commands
metric holddown
Keeps new IGRP routing information from being used for a certain period of time.
metric weights (EIGRP)
Allows the tuning of the IGRP or EIGRP metric calculations.
metric weights (IGRP)
To allow the tuning of the IGRP or Enhanced IGRP (EIGRP) metric calculations, use the metric weights command in router configuration mode. To reset the values to their defaults, use the no form of this command.
metric weights tos k1 k2 k3 k4 k5
no metric weights
Syntax Description
tos
Type of service must always be zero.
k1 k2 k3 k4 k5
Constants that convert an IGRP or EIGRP metric vector into a scalar quantity.
Defaults
tos: 0
k1: 1
k2: 0
k3: 1
k4: 0
k5: 0
Command Modes
Router configuration
Command History
Usage Guidelines
Use this command to alter the default behavior of IGRP routing and metric computation and allow the tuning of the IGRP metric calculation for a particular type of service (ToS).
If k5 equals 0, the composite IGRP or EIGRP metric is computed according to the following formula:
metric = [k1 * bandwidth + (k2 * bandwidth)/(256 - load) + k3 * delay]
If k5 does not equal zero, an additional operation is performed:
metric = metric * [k5/(reliability + k4)]
Bandwidth is inverse minimum bandwidth of the path in BPS scaled by a factor of 2.56 * 1012. The range is from a 1200-bps line to 10 terabits per second.
Delay is in units of 10 microseconds. The range of delay is from 10 microseconds to 168 seconds. A delay of all ones indicates that the network is unreachable.
The delay parameter is stored in a 32-bit field, in increments of 39.1 nanoseconds. The range of delay is from 1 (39.1 nanoseconds) to hexadecimal FFFFFFFF (decimal 4,294,967,040 nanoseconds). A delay of all ones (that is, a delay of hexadecimal FFFFFFFF) indicates that the network is unreachable.
Table 4 lists the default values used for several common media.
Reliability is given as a fraction of 255. That is, 255 is 100 percent reliability or a perfectly stable link.
Load is given as a fraction of 255. A load of 255 indicates a completely saturated link.
Examples
The following example sets the metric weights to slightly different values than the defaults:
router igrp 109network 192.168.0.0metric weights 0 2 0 2 0 0Related Commands
neighbor (IGRP)
To define a neighboring router with which to exchange routing information, use the neighbor command in router configuration mode. To remove an entry, use the no form of this command.
neighbor ip-address
no neighbor ip-address
Syntax Description
Defaults
No neighboring routers are defined.
Command Modes
Router configuration
Command History
Usage Guidelines
This command permits the point-to-point (nonbroadcast) exchange of routing information. When used in combination with the passive-interface router configuration command, routing information can be exchanged between a subset of routers and access servers on a LAN.
Multiple neighbor commands can be used to specify additional neighbors or peers.
Examples
In the following example, Interior Gateway Routing Protocol (IGRP) updates are sent to all interfaces on network 192.168.0.0 except Ethernet interface 1. However, in this case a neighbor router configuration command is included. This command permits the sending of routing updates to specific neighbors. One copy of the routing update is generated per neighbor.
router igrp 109network 192.168.0.0passive-interface ethernet 1neighbor 192.168.20.4Related Commands
network (IGRP)
To specify a list of networks for the Enhanced Interior Gateway Routing Protocol (IGRP) routing process, use the network command in router configuration mode. To remove an entry, use the no form of this command.
network network-number
no network network-number
Syntax Description
Defaults
No networks are specified.
Command Modes
Router configuration
Command History
Usage Guidelines
The network number specified must not contain any subnet information. There is no limit to the number of network commands you can use on the router.
IGRP or Enhanced IGRP (EIGRP) sends updates to the interfaces in the specified networks. Also, if a network interface is not specified, it will not be advertised in any IGRP or EIGRP update.
Examples
The following example configures a router for IGRP and assigns autonomous system 109. The network commands indicate the networks directly connected to the router.
router igrp 109network 10.108.0.0network 192.168.7.0Related Commands
offset-list (IGRP)
To add an offset to incoming and outgoing metrics to routes learned via Interior Gateway Routing Protocol (IGRP), use the offset-list command in router configuration mode. To remove an offset list, use the no form of this command.
offset-list {access-list-number | access-list-name} {in | out} offset [interface-type interface-number]
no offset-list {access-list-number | access-list-name} {in | out} offset [interface-type interface-number]
Syntax Description
Defaults
This command is disabled by default.
Command Modes
Router configuration
Command History
10.0
This command was introduced.
10.3
The interface-type and interface-number arguments were added.
11.2
The access-list-name argument was added.
Usage Guidelines
The offset value is added to the routing metric. An offset list with an interface type and interface number is considered extended and takes precedence over an offset list that is not extended. Therefore, if an entry passes the extended offset list and the normal offset list, the offset of the extended offset list is added to the metric.
Examples
In the following example, the router applies an offset of 10 to the delay component of the router only to access list 121:
offset-list 21 out 10In the following example, the router applies an offset of 10 to routes learned from Ethernet interface 0:
offset-list 21 in 10 ethernet 0router igrp
To configure the Interior Gateway Routing Protocol (IGRP) routing process, use the router igrp command in global configuration mode. To shut down an IGRP routing process, use the no form of this command.
router igrp as-number
no router igrp as-number
Syntax Description
as-number
Autonomous system number that identifies the routes to the other IGRP routers. It is also used to tag the routing information.
Defaults
No IGRP routing process is defined.
Command Modes
Global configuration
Command History
Usage Guidelines
It is not necessary to have a registered autonomous system number to use IGRP. If you do not have a registered number, you are free to create your own. We recommend that if you do have a registered number, you use it to identify the IGRP process.
Examples
The following example configures an IGRP routing process and assigns process number 109:
router igrp 109Related Commands
network (IGRP)
Specifies a list of networks for the IGRP or EIGRP routing process.
set metric (IGRP)
To set the metric value for Interior Gateway Routing Protocol (IGRP) in a route map, use the set metric route-map configuration command. To return to the default metric value, use the no form of this command.
set metric bandwidth delay reliability loading mtu
no set metric bandwidth delay reliability loading mtu
Syntax Description
Defaults
No metric will be set in the route map.
Command Modes
Route-map configuration
Command History
Usage Guidelines
Note
Use the route-map global configuration command, and the match and set route-map configuration commands, to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria—the conditions under which redistribution is allowed for the current route-map command. The set commands specify the set actions—the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map.
The set route-map configuration commands specify the redistribution set actions to be performed when all of the match criteria of a route map are met. When all match criteria are met, all set actions are performed.
Examples
The following example sets the bandwidth to 10,000, the delay to 10, the reliability to 255, the loading to 1, and the MTU to 1500:
set metric 10000 10 255 1 1500Related Commands
route-map (IP)
Defines the conditions for redistributing routes from one routing protocol into another.
timers basic (IGRP)
To adjust Interior Gateway Routing Protocol (IGRP) network timers, use the timers basic command in router configuration mode. To restore the default timers, use the no form of this command.
timers basic update invalid holddown flush [sleeptime]
no timers basic
Syntax Description
Defaults
update: 90 seconds
invalid: 270 seconds
holddown: 280 seconds
flush: 630 seconds
sleeptime: 0 milliseconds
Command Modes
Router configuration
Command History
Usage Guidelines
The basic timing parameters for IGRP are adjustable. Because IGRP is executing a distributed, asynchronous routing algorithm, these timers must be the same for all routers and access servers in the network.
Note
Examples
The following example sets updates to be broadcast every 5 seconds. If a router is not heard from in 15 seconds, the route is declared unusable. Further information is suppressed for an additional 15 seconds. At the end of the suppression period, the route is flushed from the routing table.
router igrp 109timers basic 5 15 15 30
Note
Related Commands
show ip protocols
Displays the parameters and current state of the active routing protocol process.
traffic-share balanced
To balance traffic distribution among routes when there are multiple routes for the same destination network that have different costs, use the traffic-share balanced command in router configuration mode. To disable this function, use the no form of the command.
traffic-share balanced
no traffic-share balanced
Syntax Description
This command has no arguments or keywords.
Defaults
Traffic is distributed proportionately to the ratios of the metrics.
Command Modes
Router configuration
Command History
Usage Guidelines
This command applies to Interior Gateway Routing Protocol (IGRP) and Enhanced IGRP (EIGRP) routing protocols only. With the default setting, routes that have higher metrics represent less-preferable routes and get less traffic.
Examples
In the following example, traffic is balanced across multiple routes:
router igrp 5traffic-share balancedvariance 1Related Commands
variance (IGRP)
To control load balancing in an Enhanced IGRP-based internetwork, use the variance command in router configuration mode. To reset the variance to the default value, use the no form of this command.
variance multiplier
no variance
Syntax Description
multiplier
Metric value used for load balancing. It can be a value from 1 to 128. The default is 1, which means equal-cost load balancing.
Defaults
1 (equal-cost load balancing)
Command Modes
Router configuration
Command History
Usage Guidelines
Setting a variance value lets the Cisco IOS software determine the feasibility of a potential route. A route is feasible if the next router in the path is closer to the destination than the current router and if the metric for the entire path is within the variance. Only paths that are feasible can be used for load balancing and included in the routing table.
If the following two conditions are met, the route is deemed feasible and can be added to the routing table:
•
•
Examples
The following example sets a variance value of 4:
router igrp 109variance 4
