Multicast and Routing Guide K/KA/KB.15.15

Table 11 RIP interface parameters (continued)
DefaultDescriptionParameter
Poison reverseThe method the routing switch uses to
prevent routing loops caused by
loop prevention
advertising a route on the same
interface as the one on which the
routing switch learned the route:
• Split horizon - The routing switch
does not advertise a route on the
same interface as the one on which
the routing switch learned the
route.
• Poison reverse - The routing 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 routing
switch learned the route.
V2-onlyDefine the RIP version for incoming
packets
receive
V2-onlyDefine the RIP version for outgoing
packets
send
Configuring RIP redistribution
You can configure the routing switch to redistribute connected, static, and OSPF routes into RIP.
When you redistribute a route into RIP, the routing switch can use RIP to advertise the route to its
RIP neighbors.
To configure redistribution, perform the following tasks:
1. Configure redistribution filters to permit or deny redistribution for a route based on the
destination network address or interface. (optional)
2. Enable redistribution.
Defining RIP redistribution filters
Route redistribution imports and translates different protocol routes into a specified protocol type.
On the switches, redistribution is supported for static routes, directly connected routes, and OSPF
routes. Redistribution of any other routing protocol into RIP is not currently supported. When you
configure redistribution for RIP, you can specify that static, connected, or OSPF routes are imported
into RIP routes. Likewise, OSPF redistribution supports the import of static, connected, or RIP routes
into OSPF routes.
Changing the route loop prevention method
RIP can use the following methods to prevent routing loops:
• Split horizon -the routing switch does not advertise a route on the same interface as the one
on which the routing switch learned the route.
• Poison reverse - the routing switch assigns a cost of 16 ("infinity" or "unreachable") to a route
before advertising it on the same interface as the one on which the routing switch learned the
route. This is the default.
These loop prevention methods are configurable on an individual VLAN interface basis.
NOTE: These methods are in addition to RIP's maximum valid route cost of 15.
Configuring RIP redistribution 139