Ripv2; Preventing Routing Loops In Rip; Rip Distribution Access Lists - Avaya G250 Administration

Configuring the router

RIPv2

RIPv2 is a newer version of the RIP routing protocol. RIPv2 solves some of the problems
associated with RIPv1. The most important change in RIPv2 is the addition of a subnetwork
mask field which allows RIPv2 to support variable length subnetworks. RIPv2 also includes an
authentication mechanism similar to the one used in OSPF. RIPv2 is defined in RFC 2453.
Table 60: RIPv1 vs. RIPv2
Table 60: RIPv1 vs. RIPv2
RIPv1
Broadcast addressing
Timer-based – updated every 30 seconds
Fixed subnetwork masks
No security
No provision for external protocols

Preventing routing loops in RIP

You can use the following features in RIP to help avoid routing loops:
Split-horizon
●
Poison-reverse
●
The split-horizon technique prevents information about routes from exiting the router interface
through which the information was received. This prevents small routing loops. Use the
ip rip split-horizon command to enable the split-horizon mechanism. Use the no form
of this command to disable the split-horizon mechanism. By default, split-horizon is enabled.
Poison-reverse updates explicitly indicate that a network or subnet is unreachable.
Poison-reverse updates are sent to defeat large routing loops. Use the ip rip
poison-reverse command to enable split-horizon with poison-reverse on an interface. Use
the no form of this command to disable the poison-reverse mechanism.

RIP distribution access lists

RIP distribution access lists consist of rules that specify how a router distributes and accepts
RIP routing information from other routers. Before sending an update, the router consults an
access list to determine if it should include specific routes in the update. When receiving an
update, the router first checks a set of rules which apply to incoming updates to determine if it
should insert those routes into its routing table. You can assign the rules per interface and per
direction.
436 Administration for the Avaya G250 and Avaya G350 Media Gateways
on page 436 summarizes the differences between RIP and RIP2.
RIPv2
Multicast addressing
Timer-based – updated every 30 seconds
VLSM support – subnet information transmitted
Security (authentication)
Provision for EGP/BGP (Route tag)