Changing The Route Loop Prevention Method - Dell PowerConnect B-RX Configuration Manual

Syntax: [no] ip rip learn-default
Configuring a RIP neighbor filter
By default, a device 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 <filter-num> permit | deny <source-ip-address> | 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:
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These loop prevention methods are configurable on a global basis as well as on an individual
interface basis. One of the methods is always in effect on an interface enabled for RIP. Thus, if you
disable one method, the other method is enabled.
NOTE
These methods are in addition to RIP's maximum valid route cost of 15.
To disable poison reverse and enable split horizon on a global basis, enter the following command.
BigIron RX(config-rip-router)# no poison-reverse
Syntax: [no] poison-reverse
To disable poison reverse and enable split horizon on an interface, enter commands such as the
following.
BigIron RX(config-if-e10000-1/1)# no ip rip poison-reverse
Syntax: [no] ip rip poison-reverse
BigIron RX Series Configuration Guide
53-1002253-01
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.
Configuring RIP parameters
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