One way single redistribution loop.

[Vadym Belyayev]

Hello,

I wanted to know based on the simple example below the root cause for a loop or whatever is causing the traffic not to reach its destination.

I tried debug ip routing, debug ip icmp, but it doesnt show anything which could help me to troubleshoot this issue.

The routing tables on the target routers are ok, however, the traffic is not making it to the destination.

I seems easy at first sign, but I would like to know a root cause at a lower level.

1. lo0 and lo1 are routes redistributed into EIGRP domain.

2. One way redistribution is configured only on R2

3. R4 receives the route

4. (I suppose it sends the route to R2 via OSPF, however, I do not see it in the R2s database)

5. Why R4 cannot reach 1.1.1.1? The routing table in the R4 is ok pointing to R2, R2 has the route to 1.1.1.0 via R1, however, a ping from R4 to 1.1.1.1 doesnt pass.

I tried even doing wireshark on R4s interface to see what traffic leaves the interface, but I guess it is something that cannot be verified with a wireshark.

I fixed this turning one way redistribution into two way redistribution on R2, denying the 1.1.1.0 and all the other networks from EIGRP domain to be advertised by OSPF.

But I wanted to know what is going on inside the router R2 and why it doesnt allow the traffic to reach 1.1.1.0.

Please, help me, I have read many articles, googled, even found interesting things here, but was not able to get closer to understand the issue.

[paul driver · Accepted solution]

Hello

does R1 have a route to R4? for.the return path

res
Paul
Sent from Cisco Technical Support Android App

[Vadym Belyayev]

... I am so stupid.. It doesnt have, I dont know why I didnt think about that.

Thank you very much pdriver, I cannot believe I missed such a simple thing

[paul driver]

Hello Vadym
Don't worry about that sometimes the answer can be facing us we cannot see it -Do you now have connection.

Please don't forget to rate any post that may have been helpful

Res
Paul



Sent from Cisco Technical Support iPad App

[Vadym Belyayev]

pdriver

Yes, thank you very much, it works now. I am trying to go to every detail and reproduce all the CCNP labs, so I can understand it better.

This is my 2nd post here, so I did not rate. Sorry about 4 starts, I did it by accident, did not realize how it works..

[Julio Carvajal]

Hello Vadym,

Good to know that everyone is helping you here

FYI you can mark the question as answered every time you got a solution to your problem as this case

I will do it this time for you but again great to hear that everyone is helping you,

Remember to rate all of the helpful posts

Julio Carvajal Segura

Advanced Security Trainer