Figure
shows a network
that produces a RIP hop-count limit problem. Router R2 is receiving an update
for a RIP route, which is more than 15 hops away. R2 does not install that
route in the routing table, as demonstrated in the output.

Debugs and Verification
The most logical way to start
troubleshooting this problem is to look at the routing table of the
intermediary routers along the way (R1 in this example) and determine whether
they are receiving a route for the 131.108.6.0/24 network. Figure
shows that
router R1 is receiving RIP routes for the 131.108.6.0/24 network.
Router
R1 is receiving the route in question, but with a metric of 15. R1 will add 1
more to 15 when it advertises this route to R2, which results in an infinite
metric, consequently preventing the route from being placed in the routing
table.
To verify this, use the output of debug ip
rip command on R1.
The RIP update
for the 131.108.6.0/24 network is being sent with a metric of 16 out its
Ethernet 1 interface towards router R2.
Figure
shows the output
of debug ip rip command on router R2. Router R2 receives
this update and discards it because the metric shows that this network has an
infinite distance and is therefore unreachable.
Solution
Use a routing protocol that does not have a 15-hop
limitation.