3.1 Introduction
RIP is a dynamic routing protocol used on small-scale networks. It is an Interior Gateway
Protocol (IGP) and uses the distance-vector routing algorithm.
3.1.1 Overview of RIP
RIP is widely used on small-scale network because it is simple to deploy and easier to configure
and maintain than OSPF and IS-IS.
The Routing Information Protocol (RIP) is a simple Interior Gateway Protocol (IGP). RIP is
mainly used on small-scale networks such as campus networks and simple regional networks.
RIP uses the distance-vector routing algorithm and exchanges routing information by using User
Datagram Protocol (UDP) packets through port 520.
RIP uses the hop count to measure the distance to the destination. The distance is called the
routing metric. In RIP, the hop count from a router to its directly connected network is 0, and
the hop count from a router to a network, which can be reached through another router, is 1. To
speed up route convergence, RIP defines the cost as an integer that ranges from 0 to 15. If the
hop count is equal to or exceeds 16, the destination network or host is unreachable because the
path is considered to have an infinite metric. It is this limitation to the hop count that makes RIP
inapplicable to large-scale networks.
To improve network performance and prevent routing loops, RIP supports both split horizon
and poison reverse.
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Split horizon is a method of preventing routing loops in a network and reducing bandwidth
consumption. The basic principle is simple: Information about the routing for a particular
packet is never sent back in the direction from which it was received.
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Poison reverse is that RIP sets the cost of the route learnt from an interface of a neighbor
to 16 (specifying the route as unreachable) and then sends the route from the interface back
to the neighbor. In this way, RIP can delete useless routes from the routing table of the
neighbor.
RIP has two versions:
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RIPv1
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RIPv2
RIPv1 is a classful routing protocol, whereas RIPv2 is a classless routing protocol. In RIPv2,
address 224.0.0.9 is the multicast address of a RIP router.
Compared with RIPv1, RIPv2 has the following advantages:
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Supports route tag and can flexibly control routes on the basis of the tag in the routing
policy.
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Provides packets that contain mask information and supports route aggregation and
Classless Inter-domain Routing (CIDR).
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Supports the next hop address and can select the optimal next hop address in the broadcast
network.
HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
3 RIP Configuration
Issue 02 (2014-09-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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