Dell PowerConnect B-RX BigIron RX Series Configuration Guide v02.7.02 - Page 741

Configuring RIP parameters 24 • Learning of standard RIP routes - By default, the device can learn RIP routes from all its RIP neighbors. You can configure RIP neighbor filters to explicitly permit or deny learning from specific neighbors. Enabling learning of RIP default routes By default, the device does not learn default RIP routes. You can enable learning of RIP default routes on a global or interface basis. To enable learning of default RIP routes on a global basis, enter the following command. BigIron RX(config-rip-router)# learn-default Syntax: [no] learn-default To enable learning of default RIP routes on an interface, enter commands such as the following. BigIron RX(config)# interface ethernet 1/1 BigIron RX(config-if-e10000-1/1)# ip rip learn-default Syntax: [no] ip rip learn-default Configuring a RIP neighbor filter By default, a BigIron RX 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. BigIron RX(config-rip-router)# neighbor 1 deny any Syntax: [no] neighbor permit | deny | any This command configures the device so that the device does not learn any RIP routes from any RIP neighbors. The following commands configure the device to learn routes from all neighbors except 192.168.1.170. 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. Thus, to deny learning from a specific neighbor but allow all other neighbors, you must add a filter that allows learning from all neighbors. Make sure you add the filter to permit all neighbors as the last filter (the one with the highest filter number). Otherwise, the software can match on the permit all filter before a filter that denies a specific neighbor, and learn routes from that neighbor. BigIron RX(config-rip-router)# neighbor 2 deny 192.16.1.170 BigIron RX(config-rip-router)# neighbor 1024 permit any Changing the route loop prevention method RIP uses the following methods to prevent routing loops: • Split horizon - The device does not advertise a route on the same interface as the one on which the router learned the route. • Poison reverse - The device 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. BigIron RX Series Configuration Guide 669 53-1001810-01