Changing the route loop prevention method, Configuring a rip neighbor filter – Brocade TurboIron 24X Series Configuration Guide User Manual

Page 633

Advertising
background image

Brocade TurboIron 24X Series Configuration Guide

599

53-1003053-01

Configuring RIP parameters

Configuring a RIP neighbor filter

By default, a Layer 3 Switch learns RIP routes from all its RIP neighbors. Neighbor filters allow you
to specify the neighbor routers from which the device can receive RIP routes. Neighbor filters apply
globally to all ports.

To configure a RIP neighbor filters, enter a command such as the following.

TurboIron(config-rip-router)#neighbor 1 deny any

Syntax: [no] neighbor <filter-num> permit | deny <source-ip-address> | any

This command configures the Layer 3 Switch so that the device does not learn any RIP routes from
any RIP neighbors.

The following commands configure the Layer 3 Switch to learn routes from all neighbors except
10.168.1.170. Once you define a RIP neighbor filter, the default action changes from learning all
routes from all neighbors to denying all routes from all neighbors except the ones you explicitly
permit. To deny learning from a specific neighbor but allow all other neighbors, you must add a
filter that allows learning from all neighbors. Be sure to add the filter to permit all neighbors last
(the one with the highest filter number). Otherwise, the software can match on the permit all filter
instead of a filter that denies a specific neighbor, and learn routes from that neighbor.

TurboIron(config-rip-router)#neighbor 2 deny 10.168.1.170

TurboIron(config-rip-router)#neighbor 1024 permit any

Changing the route loop prevention method

RIP can use the following methods to prevent routing loops:

Split horizon – The Layer 3 Switch does not advertise a route on the same interface as the one
on which the router learned the route.

Poison reverse – The Layer 3 Switch assigns a cost of 16 (“infinite” or “unreachable”) to a
route before advertising it on the same interface as the one on which the router learned the
route. This is the default.

These loop prevention methods are configurable on an individual interface basis. One of the
methods is always in effect on an interface enabled for RIP. If you disable one method, the other
method is enabled.

NOTE

These methods may be used in addition to RIP maximum valid route cost of 15.

To disable poison reverse and enable split horizon on an interface, enter commands such as the
following.

TurboIron(config)#interface ethernet 1

TurboIron(config-if-1)#no ip rip poison-reverse

Syntax: [no] ip rip poison-reverse

To disable split horizon and enable poison reverse on an interface, enter commands such as the
following.

TurboIron(config)#interface ethernet 1

TurboIron(config-if-1)#ip rip poison-reverse

Advertising