Ticket #01

Ticket #01

Network diagram

IGP diagram


The problem:

R1 can't ping R3's Lo0 IP address.

The solution:

First lets try to ping R3's Lo0 IP address.

On R1:

R1#ping 4.100.99.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.100.99.3, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

Indeed, R1 can't ping R3's Lo0 IP address.


Does R1 have a route to R3's Lo0 IP address? Lets check it out.


On R1:

R1#sh ip route 4.100.99.3
% Subnet not in table

R1 has no route to R3's Lo0. Maybe R3 has a default gateway route?

On R1:

R1#sh ip route 0.0.0.0
% Network not in table

No default route either.

Looking at the network diagrams, we can see that R1 should have learned the route to R3's Lo0 via RIP. We can also see that R2 should have learned the route to R3's Lo0 via OSPF.

Lets have a look at how R2 was configured to redistribute the OSPF route to RIP.

On R2:

R2#sh run | sec router rip
router rip
 version 2
 redistribute ospf 1
 network 4.0.0.0
 no auto-summary

We can see that R2 was configured to redistribute OSPF routes into RIP. Lets check if the route to R3's Lo0 is in R2's RIP database.

On R2:

R2#sh ip rip database 
4.0.0.0/8    auto-summary
4.100.12.0/24    directly connected, FastEthernet0/0
4.100.23.0/24    directly connected, FastEthernet0/1
4.100.99.1/32
    [1] via 4.100.12.1, 00:00:06, FastEthernet0/0
4.100.99.2/32    directly connected, Loopback0

It's not there! Does R2 have an OSPF route to R3's Lo0 at all?

On R2:

R2#show ip route 4.100.99.3
Routing entry for 4.100.99.3/32
  Known via "ospf 1", distance 110, metric 2, type intra area
  Redistributing via rip
  Last update from 4.100.23.3 on FastEthernet0/1, 01:59:02 ago
  Routing Descriptor Blocks:
  * 4.100.23.3, from 4.100.99.3, 01:59:02 ago, via FastEthernet0/1
      Route metric is 2, traffic share count is 1

R2 do have a route to R3's Lo0. R2 learned it via OSPF and redistributes it to RIP. But we do not see the route in RIP. Why so?

Lets have another look at R2's RIP configuration.

On R2:

R2#sh run | sec router rip
router rip
 version 2
 redistribute ospf 1
 network 4.0.0.0
 no auto-summary

There is something missing in the redistribute command. There is no metric defined to the redistributed route! Lets reconfigure the redistribution and have another look at R1's routing table.

On R2:

R2(config)#router rip
R2(config-router)#redistribute ospf 1 metric 1

On R1:

R1#sh ip route 4.100.99.3
Routing entry for 4.100.99.3/32
  Known via "rip", distance 120, metric 1
  Redistributing via rip
  Last update from 4.100.12.2 on FastEthernet0/0, 00:00:13 ago
  Routing Descriptor Blocks:
  * 4.100.12.2, from 4.100.12.2, 00:00:13 ago, via FastEthernet0/0
      Route metric is 1, traffic share count is 1

Now R1 has a route to R3's Lo0. Lets try to ping to R3's Lo0 IP address from R1.

On R1:

R1#ping 4.100.99.3       

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.100.99.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/10/20 ms


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