3com 5500-SI Manual De Usuario

RIP 225

■

Cost—The cost for the router to reach the destination, which should be an integer 
in the range of 0 to 16.

■

Timer—The length of time from the last time that the routing entry was modified 
until now. The timer is reset to 0 whenever a routing entry is modified.

■

Route tag—The indication whether the route is generated by an interior routing 
protocol or by an exterior routing protocol.

The process of RIP startup and operation is as follows:

1 If RIP is enabled on a router for the first time, the router broadcasts or multicasts a 

request packet to the adjacent routers. When they receive the request packet, 
adjacent routers (on which RIP is also enabled) respond to the request by returning 
response packets containing information about their local routing tables.

2 After receiving the response packets, the router that sent the request modifies its own 

routing table.

3 RIP broadcasts its routing table to the adjacent routers every 30 seconds. The adjacent 

routers maintain their own routing table after receiving the packets and elect an 
optimal route. They then advertise the modification information to their adjacent 
network to make the updated route globally available. RIP uses the timeout 
mechanism to handle timed out routes to ensure the timeliness and validity of the 
routes. With these mechanisms, RIP, an interior routing protocol, enables the router to 
learn the routing information of the entire network.

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

RIP configuration is described in the following sections:

■

■

Only after RIP is enabled can other functional features be configured. But the 
configuration of the interface-related functional features is not dependent on 
whether RIP has been enabled. 

The RIP configuration tasks are described in the following sections:

■

■

■

■

■

■

■

■

■

■

■