What's RIP

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History

The Routing Information Protocol (RIP) was one of the earliest intra-AS Internet routing protocols and is still in widespread use today. It traces its origins and its name to the Xerox Network Systems (XNS ) architecture. The widespread deployment of RIP was due in great part to its inclusion in 1982 of the Berkley Software Distribution (BSD) version of UNIX supporting TCP/IP. RIP version 1 is defined in RFC 1058, with a backward- compatible ver.2 defined in RFC 2453.

Distance Vector Routing Algorithm

Now recall the distance vector (DV), and look at its features.
DV algorithm is iterative, asynchronous and distributed one;

It is distributed in that each node receives some information from one or more of its directly attached neighbors performs a calculation, and may then distribute the results of its calculation back to its neighbors.
It is iterative in that this process continues on until no more information is exchanged between neighbors.
This algorithm is asynchronous in that it does not require all of the nodes to operate in lockstep with each other.

Main Features of RIP

RIP is a Distance Vector protocol that operates in a manner very close to the idealized protocol, which allows neighboring routers to exchange the routing information with each other. The features of RIP are as follows;

RIP for IPv4 ; RFC 1058/1721/1722/1723/1724
RIP for IPv6 ; RFC 2080
Routed in BSD, SunOS
Maximum hopping; 15
Cold-Start ; It takes at most 450s(=15x30 ) for calculate.
Exchange Distance Vector database (routing table) information every 30 sec.( using UDP port 520)
->transfer about the condition change of node/link
If there is no response for 180 sec, the network is down (keep-alive)

Expression for Minimum Distance Path;
D(i,j) ; distance vector
d(i,j) ; distance between node_i and node_j
D(i,j) = min [d(i,k) + D(k,j)] (for all k)

Bellman-Ford’s Algorithm

Bellman-Ford’s algorithm was developed by Xerox-PARC as XNS-RIP. It define the optimum path to the destination; minimum distance and attribute distance vector information. This algorithm is mathematically expressed as following table.

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