Stands for "Routing Information Protocol." RIP is a protocol used by routers to exchange routing information on a network. Its primary functions are to 1) determine the most efficient way to route data on a network and 2) prevent routing loops.
RIP maintains a routing table, which lists all routers reachable within a network. Each router uses this table to determine the most efficient way to route data. RIP incorporates distance-vector routing, which calculates the best path based on the direction and distance between routers. Each packet is forwarded to the appropriate routers until the packet reaches its destination.
RIP also prevents endless routing loops by limiting the number of "hops" between the source and destination. A hop is recorded each time a packet is forwarded from one router to another. The maximum number of hops allowed by RIP is 15. If the hop count hits 16, RIP determines the destination is not reachable and the transfer is terminated.
Three different versions of RIP exist:
- RIPv1 - standardized in 1988; uses "classful" routing, which defines an IP class, but does not include subnet information
- RIPv2 - developed in 1993 and standardized in 1998; uses "classless" routing and carries subnet information; supports MD5 authentication
- RIPng - standardized in 1997; an extension of RIPv2 that supports IPv6
NOTE: Most modern networks use newer routing methods, such as OSPF (Open Shortest Path First), rather than RIP to route data.