IGRP Commands
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IGRP Commands

Table Of Contents

IGRP Commands

default-metric (IGRP)

distribute-list in (RIP, IGRP, EIGRP)

distribute-list out (RIP, IGRP, EIGRP)

ip split-horizon (IGRP)

metric holddown

metric maximum-hops

metric weights (IGRP)

neighbor (IGRP)

network (IGRP)

offset-list (IGRP)

router igrp

set metric (IGRP)

timers basic (IGRP)

traffic-share balanced

variance (IGRP)


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

bandwidth

Minimum bandwidth of the route (in kbps). It can be 0 or any positive integer.

delay

Route delay (in tens of microseconds). It can be 0 or any positive number that is a multiple of 39.1 nanoseconds.

reliability

Likelihood of successful packet transmission expressed as a number from 0 to 255. The value 255 means 100 percent reliability; 0 means no reliability.

loading

Effective bandwidth of the route expressed as a number from 0 to 255 (255 is 100 percent loading).

mtu

Maximum transmission unit (MTU) size of the route in bytes. It can be 0 or any positive integer.


Defaults

Only connected routes and interface static routes can be redistributed without a default metric.

Command Modes

Router configuration

Command History

Release
Modification

10.0

This command was introduced.


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 109
 network 172.16.0.0
 redistribute rip
 default-metric 1000 100 250 100 1500

Related Commands

Command
Description

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

access-list-number

Standard IP access list number. The list defines which networks are to be received and which are to be suppressed in routing updates.

prefix prefix-list-name

Name of a prefix list. The list defines which networks are to be received and which are to be suppressed in routing updates, based upon matching the network prefix to the prefixes in the list.

gateway prefix-list-name

(Optional) Name of the prefix list to be applied to the gateway of the prefix being updated.

in

Applies the access list to incoming routing updates.

interface-type

(Optional) Interface type.

interface-number

(Optional) Interface number on which the access list should be applied to incoming updates. If no interface is specified, the access list will be applied to all incoming updates.


Defaults

This command is disabled by default.

Command Modes

Address family configuration

Router configuration

Command History

Release
Modification

10.0

This command was introduced.

11.2

The access-list-number, interface-type, and interface-number arguments were added.

12.0

The prefix-list-name argument was added.

12.0(7)T

Address family configuration mode was added.


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 0.0.0.0
access-list 1 permit 192.168.0.0
access-list 1 deny 0.0.0.0 255.255.255.255
router bgp 
 network 192.168.0.0
 distribute-list 1 in

In 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 24
router rip
 network 192.168.0.0
 distribute-list prefix max24 in

In 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 24
ip prefix-list allowlist seq5 permit 192.168.1.1/32
router rip
 network 10.108.0.0
 distribute-list prefix max24 gateway allowlist in

Related Commands

Command
Description

access-list (IP extended)

Defines an extended IP access list.

distribute-list out (RIP, IGRP, EIGRP)

Suppresses networks from being advertised in updates.

ip prefix-list

Creates an entry in a prefix list.

redistribute (IP)

Redistributes routes from one routing domain into another routing domain.


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

access-list-number

Standard IP access list number. The list defines which networks are to be received and which are to be suppressed in routing updates.

prefix prefix-list-name

Name of a prefix list. The list defines which networks are to be received and which are to be suppressed in routing updates, based upon matching the network prefix to the prefixes in the list.

gateway prefix-list-name

(Optional) Name of the prefix list to be applied to the gateway of the prefix being updated.

out

Applies the access list to outgoing routing updates.

interface-name

(Optional) Name of a particular interface.

routing-process

(Optional) Name of a particular routing process, or the keyword static or connected.

as-number

(Optional) Autonomous system number.


Defaults

This command is disabled by default.

Command Modes

Address family configuration

Router configuration

Command History

Release
Modification

10.0

This command was introduced.

11.2

The access-list-number argument was added.

12.0

The prefix-list-name argument was added.

12.0(7)T

Address family configuration mode was added.


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 To filter networks received in updates, use the distribute-list in command.


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 192.168.0.0
access-list 1 deny 0.0.0.0 255.255.255.255
router rip
 network 192.168.0.0
 distribute-list 1 out

Related Commands

Command
Description

access-list (IP extended)

Defines an extended IP access list.

distribute-list in (RIP, IGRP, EIGRP)

Filters networks received in updates.

ip prefix-list

Creates an entry in a prefix list.


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

Release
Modification

10.0

This command was introduced.


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 For networks that include links over X.25 packet-switched networks (PSNs), the neighbor router configuration command can be used to defeat the split horizon feature. You can as an alternative explicitly specify the no ip split-horizon command in your configuration. However, if you do so you must similarly disable split horizon for all routers in any relevant multicast groups on that network.



Note If split horizon has been disabled on an interface and you want to enable it, use the ip split-horizon command to restore the split horizon mechanism.



Note In general, changing the state of the default for the ip split-horizon command is not recommended, unless you are certain that your application requires a change in order to advertise routes properly. If split horizon is disabled on a serial interface (and that interface is attached to a PSN), you must disable split horizon for all routers and access servers in any relevant multicast groups on that network.


Examples

The following simple example disables split horizon on a serial link. The serial link is connected to an X.25 network.

interface serial 0
 encapsulation x25
 no ip split-horizon

Related Commands

Command
Description

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

Release
Modification

10.0

This command was introduced.


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 15
 network 10.108.0.0
 network 192.168.7.0
 no metric holddown

Related Commands

Command
Description

metric maximum-hops

Causes the IP routing software to advertise as unreachable those routes with a hop count higher than is specified by the command (IGRP only).

metric weights (EIGRP)

Allows the tuning of the IGRP or EIGRP metric calculation.

timers basic (IGRP)

Adjusts IGRP network timers.


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

Release
Modification

10.0

This command was introduced.


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 71
 network 10.0.0.0
 metric maximum-hops 200

Related Commands

Command
Description

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

Release
Modification

10.0

This command was introduced.


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.

Table 4 Bandwidth Values by Media Type 

Media Type
Delay
Bandwidth

Satellite

5120 (2 seconds)

5120 (500 megabits)

Ethernet

25600 (1 [ms])

256000 (10 megabits)

1.544 Mbps

512000 (20,000 [ms])

1,657,856 bits

64 kbps

512000 (20,000 [ms])

40,000,000 bits

56 kbps

512000 (20,000 [ms])

45,714,176 bits

10 kbps

512000 (20,000 [ms])

256,000,000 bits

1 kbps

512000 (20,000 [ms])

2,560,000,000 bits


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 109
 network 192.168.0.0
 metric weights 0 2 0 2 0 0

Related Commands

Command
Description

bandwidth (interface)

Sets a bandwidth value for an interface.

delay (interface)

Sets a delay value for an interface.

metric holddown

Keeps new IGRP routing information from being used for a certain period of time.

metric maximum-hops

Causes the IP routing software to advertise as unreachable those routes with a hop count higher than is specified by the command (IGRP only).


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

ip-address

IP address of a peer router with which routing information will be exchanged.


Defaults

No neighboring routers are defined.

Command Modes

Router configuration

Command History

Release
Modification

10.0

This command was introduced.


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 109
 network 192.168.0.0
 passive-interface ethernet 1
 neighbor 192.168.20.4

Related Commands

Command
Description

passive-interface

Disables sending routing updates on an interface.


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

network-number

IP address of the directly connected networks.


Defaults

No networks are specified.

Command Modes

Router configuration

Command History

Release
Modification

10.0

This command was introduced.


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 109
 network 10.108.0.0
 network 192.168.7.0

Related Commands

Command
Description

router igrp

Configures the IGRP routing process.


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

access-list-number

Standard access list number to be applied. Access list number 0 indicates all access lists. If the offset argument is 0, no action is taken. For IGRP, the offset is added to the delay component only.

access-list-name

Standard access name to be applied.

in

Applies the access list to incoming metrics.

out

Applies the access list to outgoing metrics.

offset

Positive offset to be applied to metrics for networks matching the access list. If the offset is 0, no action is taken.

interface-type

(Optional) Interface type to which the offset list is applied.

interface-number

(Optional) Interface number to which the offset list is applied.


Defaults

This command is disabled by default.

Command Modes

Router configuration

Command History

Release
Modification

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 10

In the following example, the router applies an offset of 10 to routes learned from Ethernet interface 0:

offset-list 21 in 10 ethernet 0

router 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

Release
Modification

10.0

This command was introduced.


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 109

Related Commands

Command
Description

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

bandwidth

Metric value or IGRP bandwidth of the route, in kbps. It can be in the range from 0 to 4294967295.

delay

Route delay (in tens of microseconds). It can be in the range from 0 to 4294967295.

reliability

Likelihood of successful packet transmission expressed as a number from 0 to 255. The value 255 means 100 percent reliability; 0 means no reliability.

loading

Effective bandwidth of the route expressed as a number from 0 to 255 (255 is 100 percent loading).

mtu

Minimum maximum transmission unit (MTU) size of the route, in bytes. It can be in the range from 0 to 4294967295.


Defaults

No metric will be set in the route map.

Command Modes

Route-map configuration

Command History

Release
Modification

10.0

This command was introduced.


Usage Guidelines


Note We recommend that you consult your Cisco technical support representative before changing the default value.


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 1500

Related Commands

Command
Description

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

update

Rate (in seconds) at which updates are sent. This is the fundamental timing parameter of the routing protocol. The default is 90 seconds.

invalid

Interval of time (in seconds) after which a route is declared invalid; it should be at least three times the value of the update argument. A route becomes invalid when there is an absence of updates that refresh the route. The route then enters holddown state. The route is marked inaccessible and advertised as unreachable. However, the route is still used for forwarding packets. The default is 270 seconds.

holddown

Interval (in seconds) during which routing information regarding better paths is suppressed. It should be at least three times the value of the update argument. A route enters into a hold-down state when an update packet is received that indicates the route is unreachable. The route is marked inaccessible and advertised as unreachable. However, the route is still used for forwarding packets. When holddown expires, routes advertised by other sources are accepted and the route is no longer inaccessible. The default is 280 seconds.

flush

Amount of time (in seconds) that must pass before the route is removed from the routing table; the interval specified must be at least the sum of the invalid argument and the holddown argument. If it is less than this sum, the proper holddown interval cannot elapse, which results in a new route being accepted before the holddown interval expires. The default is 630 seconds.

sleeptime

(Optional) Interval (in milliseconds) for postponing routing updates in the event of a flash update. The value of the sleeptime argument should be less than the update value. If the sleeptime value is greater than the update value, routing tables will become unsynchronized. The default is 0 milliseconds.


Defaults

update: 90 seconds

invalid: 270 seconds

holddown: 280 seconds

flush: 630 seconds

sleeptime: 0 milliseconds

Command Modes

Router configuration

Command History

Release
Modification

10.0

This command was introduced.


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 The current and default timer values can be seen by inspecting the output of the show ip protocols EXEC command. The relationships of the various timers should be preserved as described previously.


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 109
 timers basic 5  15  15  30


Note By setting a short update period, you run the risk of congesting slow-speed serial lines; however, this is not a serious concern on faster-speed Ethernets and T1-rate serial lines. Also, if you have many routes in your updates, you can cause the routers to spend an excessive amount of time processing updates.


Related Commands

Command
Description

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

Release
Modification

10.0

This command was introduced.


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 5
 traffic-share balanced
 variance 1

Related Commands

Command
Description

variance (IGRP)

Controls load balancing in an EIGRP and IGRP internetwork.



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

Release
Modification

10.0

This command was introduced.


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:

The local best metric must be greater than the metric learned from the next router.

The multiplier times the local best metric for the destination must be greater than or equal to the metric through the next router.

Examples

The following example sets a variance value of 4:

router igrp 109
 variance 4