3Com Switch 8800 Configuration Guide
Chapter 18 RIP Configuration
18-2
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Period update is triggered periodically to send all RIP routes to all neighbors.
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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.
18.1.2 RIP Enabling and Running
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.
18.2 Configuring RIP
1)
RIP basic configuration
RIP basic configuration includes:
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Enabling RIP
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Enabling RIP on specified network
