3com 8807 User Guide

C

HAPTER

 30: RIP C

ONFIGURATION

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If the RIP route is not updated (a router receives the update packets from the 
neighbor) when the Timeout timer expires, this route is regarded as 
unreachable. The cost is set to 16.

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If the Garbage-Collection timer expires, and the unreachable route receives no 
update packet from the same neighbor, the route will be completely deleted 
from the routing table.

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By default, the values of Period Update and Timeout timers are 30 seconds and 
180 seconds respectively. The value of Garbage-collection timer is four times 
that of Period Update timer: 120 seconds.

The following section describes the procedure:

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If RIP is enabled on a router for the first time, the router will broadcast or 
multicast the request packet to the adjacent routers. Upon receiving the 
request packet, the RIP on each adjacent router responds with a packet 
conveying its local routing table.

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After receiving the response packets, the router, which has sent the request, 
will modify its own routing table. At the same time, the router sends trigger 
modification packets to its adjacent routers running RIP and broadcasts 
modification information, following split horizon mechanism. After receiving 
trigger modification packets, the adjacent routers send trigger modification 
packets to their respective adjacent routers. As a result, each router can obtain 
and maintain the latest routing information.

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RIP broadcasts its routing table to the adjacent routers every 30 seconds. The 
adjacent routers will maintain their own routing table after receiving the 
packets and will select an optimal route, and then advertise the modification 
information to their respective adjacent network so as to make the updated 
route globally known. Furthermore, RIP uses the timeout mechanism to handle 
the out-timed routes so as to ensure the real-timeliness and validity of the 
routes.

RIP has become one of the actual standards of transmitting router and host routes 
by far. It can be used in most of the campus networks and the regional networks 
that are simple yet extensive. For larger and more complicated networks, RIP is not 
recommended.

1 RIP basic configuration

RIP basic configuration includes:

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Enabling RIP

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Enabling RIP on specified network

If the link, which does not support broadcast or multicast packets, runs RIP, you 
need to configure RIP to send any packet to the specified destination, establishing 
RIP neighbors correctly.

2 RIP route management