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This chapter explains the function and syntax of the Interior Gateway Routing Protocol (IGRP) commands. For more information about defaults and usage guidelines, see the corresponding chapter of the Cisco IOS IP and IP Routing Command Reference, Release 12.1.
To enable the split horizon mechanism, use the ip split-horizon interface configuration command. To disable the split horizon mechanism, use the no form of this command.
ip split-horizonSyntax Description
This command has no arguments or keywords.
To keep new Interior Gateway Routing Protocol (IGRP) routing information from being used for a certain period of time, use the metric holddown router configuration command. To disable this feature, use the no form of this command.
metric holddownSyntax Description
This command has no arguments or keywords.
To have the IP routing software to 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 router configuration command. To reset the value to the default, use the no form of this command.
metric maximum-hops hops
Syntax Description
hops Maximum hop count (in decimal). The default value is 100 hops; the maximum number of hops that can be specified is 255.
To define a neighboring router with which to exchange routing information, use the neighbor router configuration command. To remove an entry, use the no form of this command.
neighbor ip-address
Syntax Description
ip-address IP address of a peer router with which routing information will be exchanged.
To specify a list of networks for the Enhanced Interior Gateway Routing Protocol (IGRP) routing process, use the network router configuration command. To remove an entry, use the no form of this command.
network network-number
Syntax Description
network-number IP address of the directly connected networks.
To add an offset to incoming and outgoing metrics to routes learned via Interior Gateway Routing Protocol (IGRP), use the offset-list router configuration command. To remove an offset list, use the no form of this command.
offset-list {access-list-number | name} {in | out} offset [type number]
Syntax Description
access-list-number | name Standard access list number or name to be applied. Access list number 0 indicates all access lists. If offset is 0, no action is taken. For IGRP, the offset is added to the delay component only. 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. type (Optional) Interface type to which the offset-list is applied. number (Optional) Interface number to which the offset-list is applied.
To configure the Interior Gateway Routing Protocol (IGRP) routing process, use the router igrp global configuration command. To shut down an IGRP routing process, use the no form of this command.
router igrp autonomous-system
Syntax Description
autonomous-system Autonomous system number that identifies the routes to the other IGRP routers. It is also used to tag the routing information.
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
Syntax Description
bandwidth Metric value or IGRP bandwidth of the route in kilobits per second. It can be in the range 0 to 4294967295. delay Route delay in tens of microseconds. It can be in the range 0 to 4294967295. reliability Likelihood of successful packet transmission expressed as a number between 0 and 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 0 to 4294967295.
To adjust Interior Gateway Routing Protocol (IGRP) network timers, use the timers basic router configuration command. To restore the default timers, use the no form of this command.
timers basic update invalid holddown flush [sleeptime]
Syntax Description
update Rate in seconds at which updates are sent. This is the fundamental timing parameter of the routing protocol. invalid Interval of time in seconds after which a route is declared invalid; it should be at least three times the value of update. A route becomes invalid when there is an absence of updates that refresh the route. The route then enters holddown. The route is marked inaccessible and advertised as unreachable. However, the route is still used for forwarding packets. holddown Interval in seconds during which routing information regarding better paths is suppressed. It should be at least three times the value of update. A route enters into a holddown 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. 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 invalid and holddown. 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. sleeptime (Optional) Interval in milliseconds for postponing routing updates in the event of a flash update. The sleeptime value should be less than the update time. If the sleeptime is greater than the update time, routing tables will become unsynchronized.
Syntax Description
balanced Distributes traffic proportionately to the ratios of the metrics. min Uses routes that have minimum costs.
Posted: Wed Jul 26 13:59:20 PDT 2000
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