Rip Overview; Basic Concepts; Chapter 3 Rip Configuration - Huawei Quidway S3900 Series Operation Manual

Operation Manual – Routing Protocol
Quidway S3900 Series Ethernet Switches-Release 1510

Chapter 3 RIP Configuration

3.1 RIP Overview

Routing information protocol (RIP) is a simple interior gateway protocol (IGP) suitable
for small-sized networks.

3.1.1 Basic Concepts

I. RIP
RIP is a distance-vector (D-V) algorithm-based protocol. It exchanges routing
information via UDP packets.
RIP uses hop count (also called routing cost) to measure the distance to a destination
address. In RIP, the hop count from a router to its directly connected network is 0, and
that to a network which can be reached through another router is 1, and so on. To
restrict the time to converge, RIP prescribes that the cost is an integer ranging from 0
and 15. The hop count equal to or exceeding 16 is defined as infinite; that is, the
destination network or host is unreachable.
To improve performance and avoid routing loop, RIP supports split horizon. Besides,
RIP can import routes from other routing protocols.
II. RIP routing database
Each router running RIP manages a routing database, which contains routing entries
to all the reachable destinations in the internetwork. Each routing entry contains the
following information:
Destination address: IP address of a host or network.
Next hop address: IP address of an interface on the adjacent router that IP
packets should pass through to reach the destination.
Interface: Interface on this router, through which IP packets should be forwarded
to reach the destination.
Cost: Cost for the router to reach the destination.
Routing time: Time elapsed after the routing entry is updated last time. This time
is reset to 0 whenever the routing entry is updated.
III. RIP timers
As defined in RFC 1058, RIP is controlled by three timers: Period update, Timeout,
and Garbage-collection.
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Chapter 3 RIP Configuration