Configuration Guide User guide

FastIron Configuration Guide 1209
53-1002494-01
RIP parameter configuration
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 the RIP maximum valid route cost of 15.
Disabling poison-reverse
To disable poison reverse and enable split horizon on an interface, enter commands such as the
following.
Brocade(config)#interface ethernet 0/1/1
Brocade(config-if-0/1/1)#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.
Brocade(config)#interface ethernet 0/1/1
Brocade(config-if-0/1/1)#ip rip poison-reverse
Suppressing RIP route advertisement on a VRRP or
VRRP-E backup interface
NOTE
This section applies only if you configure the Layer 3 Switch for Virtual Router Redundancy Protocol
(VRRP) or VRRP Extended (VRRP-E). Refer to Chapter 39, “VRRP and VRRP-E”.
Normally, a VRRP or VRRP-E backup includes route information for the virtual IP address (the
backed-up interface) in RIP advertisements. As a result, other routers receive multiple paths for
the backed-up interface and might sometimes unsuccessfully use the path to the backup rather
than the path to the master.
You can prevent the backups from advertising route information for the backed-up interface by
enabling suppression of the advertisements.
To suppress RIP advertisements for the backed-up interface, enter the following commands.
Brocade(config)#router rip
Brocade(config-rip-router)#use-vrrp-path
Syntax: [no] use-vrrp-path
The syntax is the same for VRRP and VRRP-E.