Example 394 debug ip rip Output Displays 1661661660 Is Not Being Advertised by R1

R1#debug ip rip

RIP protocol debugging is on

RIP: sending v1 update to 255.255.255.255 via Ethernet0 (131.108.1.1) RIP: build update entries network 155.155.0.0 metric 1

Solution

This problem occurs because the next hop of 166.166.166.0/24 is 131.108.1.2. With split horizon, RIP will suppress this update from going out the same interface that 166.166.166.0/24 is learned. Notice that the route 155.155.155.0/24 was advertised by R1 because the next-hop address of that route was 10.10.10.4, which is a different interface on R1.

The solution lies in turning off split horizon on the Ethernet 0 interface of R1.

A similar situation would arise if 166.166.166.0/24 was defined as a secondary interface address on R1, which will not advertise this secondary interface address in its RIP update unless split horizon is turned off.

Example 3-95 shows the new configuration on Router R1 to solve this problem. Example 3-95 Disabling Split-Horizon on R1's Ethernet 0 Interface

interface Ethernet0 ip address 131.108.1.1 255.255.255.0 no ip split-horizon

Example 3-96 shows that after making the configuration changes, R2 is receiving 166.166.166.0/24 in the RIP updates.

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