The modern open standard version of RIP, sometimes referred to as IP RIP, is formally detailed in two separate documents. The first is known as Request for Comments (RFC) 1058 and the other as Internet Standard (STD) 56.

RIP has evolved over the years from a Classful Routing Protocol, RIP Version 1 (RIP v1), to a Classless Routing Protocol, RIP Version 2 (RIP v2). RIP v2 enhancements include:

• Ability to carry additional packet routing information.
• Authentication mechanism to secure table updates.
• Supports variable length subnet masking (VLSM).

RIP prevents routing loops from continuing indefinitely by implementing a limit on the number of hops allowed in a path from the source to a destination. The maximum number of hops in a path is 15. When a router receives a routing update that contains a new or changed entry, the metric value is increased by 1 to account for itself as a hop in the path. If this causes the metric to be incremented beyond 15, it is considered to be infinity and the network destination is considered unreachable. RIP includes a number of features that are common in other routing protocols. For example, RIP implements split horizon and holddown mechanisms to prevent incorrect routing information from being propagated.

Web Links Configuring RIP http://www.cisco.com/en/US/products/sw/ iosswrel/ps1831/products_configuration_guide_ chapter09186a00800d97f7.html#xtocid1