What Is The RIP Protocol?

Date First Published: 26th March 2022

Topic: Computer Networking

Subtopic: Internet Protocols

Article Type: Computer Terms & Definitions

Difficulty Level: 10/10

Learn more about what the RIP protocol is in this article.

Short for the routing information protocol, RIP is an application-layer protocol that routers use to exchange routing data on a network. It uses the hop count as a routing metric to identify the best path between the source and destination and prevents routing loops by limiting the number of hops allowed in a path from source to destination. 15 hops are the maximum that the RIP protocol can support.

The purpose of this protocol is to define how routers transfer information when moving traffic amongst an interconnected group of LANs. The algorithms that are used in RIP were first developed in 1969 and at that time, they were used to route information in ARPANET. However, the RIP protocol has been replaced by OSPF (Open Shortest Path First) due to its inability to handle very large and complex networks. Another protocol used to transfer routing information across autonomous systems on the internet is BGP (Border Gateway Protocol).

The RIP protocol has six key features. Network updates are occasionally exchanged, routing information is always sent, authentication is supported, the most efficient way of routing data on a network is determined, the hop count is used as a path selection metric, and different mechanisms are used to avoid loops in the network.

Note:

A hop is known as a router or a gateway that is an intermediary device between two different remote hosts, nodes, or networks. The more hops, the longer it takes for data to travel from source to its final destination.

RIP Protocol Modes

There are two modes of the RIP protocol that define how they share information with each other.

• Active - Routers share their routing table information with other routers in this mode.
• Passive - The router takes routing information with other routers, but it does not share its routing table information with other routers in this mode.

RIP Protocol Timers

The RIP protocol uses four different types of timers when it is operating.

• Holddown timer - This contains the number of seconds that the router waits before it accepts any updates. The value is 180 seconds by default. No updates can be performed to that routing entry during this time period.
• Update timer - To occasionally send updates. Every 30 seconds, a copy of its routing table is sent to all routers.
• Invalid timer - Also called a timeout timer. It is used for specifying how long a routing entry can be in the routing table without being updated. The value is 180 seconds by default. After this, it will be considered an invalid timer and the router will go to holddown period.
• Flush timer - This controls the time period between the invalidation of the router and the router being marked as unreachable and being removed from the routing table. The value is 240 seconds by default.

RIP Protocol Versions

There are three standardised versions of the RIP protocol that exist, which include:

RIP Version 1

The first version of the RIP standard was introduced in 1988. A router with RIPv1 implementation sends a request message to 255.255.255.255 every 30 seconds when it starts up and every 30 seconds afterwards. Receiving the request message, nearby routers respond with a RIPv1 segment providing their routing table. The requesting router adds the reachable IP network address, hop count, and next hop, which is the router interface IP address the RIPv1 response was sent to, to its own routing table. In addition, the requesting router updates its own routing table.

RIP Version 2

RIP version 2 (RIPv2) was developed in 1993, introduced in 1994, and approved as Internet Standard 56 in 1998 due to errors in the original RIP version. It supported Classless Inter-Domain Routing by including the ability to transport subnet information (CIDR). The hop count limit of 15 remained in place in order to maintain backwards compatibility. If all Must Be Zero protocol fields in RIPv1 messages are properly provided, RIPv2 has the ability to fully interact with the older specification. A compatibility switch feature enables acceptable compatibility modifications as well.

RIPng

RIPng (Routing Information Protocol Next Generation) is an extension of RIPv2, which offers support for IPv6, a newer version of the Internet Protocol, designed to replace IPv4. There are a number of differences between RIPv2 and RIPng. RIPng supports IPv6 networking. The next hop is transmitted in each route entry in RIPv2, but RIPng requires specific encoding of the next hop for a collection of route entries. RIPV2 supports RIPv1 updates authentication, but RIPng does not.

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