Routing Information Protocol Version 2 – RIPv2.
RIPv2 is a classless, distance vector routing protocol as defined in RFC 1723. Being a classless routing protocol, means, it includes the subnet mask with the network addresses in its routing updates.
As with other classless routing protocols, RIPv2 supports CIDR supernets, VLSM and discontiguous networks.
Due to the deficiencies of RIPv1, RIP version 2 (RIPv2) was developed in 1993 and was equipped with the ability to support subnet information and support Classless Inter-Domain Routing (CIDR).
A router that receives routing updates from multiple routers advertising the same classful summary route cannot determine which subnets belong to which summary route. This inability leads to unexpected results including misrouted packets.
However, with RIPv2, automatic summarization can be disabled with the no auto-summary command.
Automatic summarization must be disabled to support discontiguous networks.
RIPv2 still maintains the hop count limit of 15 and incorporates a password authentication mechanism. However, passwords were transmitted in clear-text format, which was found insufficient for secure communications on the Internet.
The default version of RIP is version 1. The command version 2 is used to modify RIPv1 to RIPv2.
Use The show ip protocols command to view RIP sending and receiving version 2 updates and whether or not automatic summarization is in effect.
RIPv2 is an enhancement of RIPv1’s features and extensions rather than an entirely new protocol. Some of these enhanced features include:
* Next-hop addresses included in the routing updates
*Use of multicast addresses in sending updates
*Authentication option available
Like RIPv1, RIPv2 is a distance vector routing protocol. Both versions of RIP share the following features and limitations:
*Use of hold-down and other timers to help prevent routing loops.
*Use of split horizon or split horizon with poison reverse to also help prevent routing loops.
*Use of triggered updates when there is a change in the topology for faster convergence.
*Maximum hop count limit of 15 hops, with the hop count of 16 signifying an unreachable network.
Key points:
+ RIP uses hop counts to calculate optimal routes (a hop is a router).
+ RIP routing is limited to 15 hops to any location (16 hops mark the network as unreachable).
+ RIP uses the split horizon with poison reverse method to prevent the count-to-infinity problem.
+ RIP uses only classful routing, so it uses full address classes, not subnets.
+ RIP broadcasts updates to the entire network.
+ RIP can maintain up to six multiple paths to each network, but only if the cost is the same.
+ RIP supports load balancing over same-cost paths.
+ The update interval default is 30, the invalid timer default is 180, the holddown timer default is 180, and the flush timer default is 240.
How to Configure RIPv2 on Cisco Routers
