RIP General Operation, Messaging, and Timers
RIP is a protocol for exchanging routing information, so its operation can best be described in terms of the messages used to exchange this information and the rules for when messages are sent. The RIP software in each router sends messages and takes other actions both in reaction to certain events and in response to triggers set off by timers. Timers are also used to determine when routing information should be discarded if it is not updated.
RIP Messages and Basic Message Types
Communication between RIP software elements in routers on an internetwork is accomplished through the use of RIP messages. These messages are sent using the UDP, with the UDP port number 520 reserved for RIP-1 and RIP-2, and ...