Routing information protocol

Routing Information Protocol was the most commonly used interior gateway protocol in the Internet. RIP was first developed in 1969 as part of ARPANET using the Bellman-Ford[?] algorithm. RIP is a distance-vector routing protocol which employs hop count as a routing metric. The maximum number of hops allowed with RIP is 15. RIP updates every 30 seconds, generating lots of network traffic in larger networks. As with all routing protocols it is at the network layer of the OSI model. It operates over UDP on port 520. Holddowns, split horizon and poison reverse[?] are used to avoid routing loops.

There are two versions of RIP, namely RIPv1 and RIPv2. RIPv1, is only capable of classful routing. The routing updates do not carry subnet information and therefore relies on the default classful networks built into IP addresses.

Due to the original deficiencies in addressing, RIPv2 was developed in 1994 to use CIDR (Classless interdomain routing). However to maintain backwards compatibility the 15 hop count limit remained. Authentication was added to secure routing updates.

In many current networking environments RIP would not be the first choice of routing protocol as its convergence times and scalability are poor compared to OSPF or IS-IS, and the hop limit severely limits the size of network it can be used in.

RIPv2 is specified in RFC 2453 or STD 56.