Routing Information Protocol
From open-encyclopedia.com - the free encyclopedia.
de:Routing Information Protocol pl:Routing Information Protocol
This article is chiefly about the Routing Information Protocol for IPv4.
The Routing Information Protocol (RIP) is one of the most commonly used Interior Gateway Protocols on internal networks (and to a lesser extent, the internet), which helps routers dynamically adapt to changes of network connections by communicating information about which networks each router can reach and how far away those networks are. Although RIP is still actively used, it is generally considered to have been obsoleted by Link-state routing protocols such as OSPF EIGRP.
RIP was first developed in 1969 as part of ARPANET, and used 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. Each RIP router transmits full updates every 30 seconds by default, generating large amounts of network traffic in lower bandwidth networks. It runs above the network layer of the Internet protocol suite, using UDP port 520 to carry its data. A mechanism called split horizon with limited poison reverse is used to avoid routing loops. Routers of some brands also use a holddown mechanism known as heuristics, whose usefulness is arguable and is not a part of the standard protocol.
There are two versions of RIP, RIPv1 and RIPv2. RIPv1 uses classful routing. The routing updates do not carry subnet information, which means that a network's size is determined solely by the network class of its IP Address, and there is no way to split a network into smaller subnets, each routed along a different path.
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. Rudimentary Simple Text authentication was added to secure routing updates. RIP Routers may also implement MD5 authentication as specified in RFC 2082.
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. On the other hand, it is easier to configure.
RIPv1 is specified in RFC 1058. RIPv2 is specified in RFC 2453 or STD 56.
