Unanswered Question
Jan 15th, 2009
User Badges:

Hello everybody

It is my first time writing here and I would like to thank you for spending your time on my question.

So,I am a CCNA candidate and I came up with a problem.I connected back to back two cisco routers (2610XM using the low speed serial int and 2600 using the serial and providind the clocking at 64000).The problem is that if I have nat configured,EIGRP is not working and when I use debug it shows that one router is finding the other but after a while looses the adjajency.At the show ip route, I am getting no EIGRP routes.If I use OSPF everything's working.No auto-summary is configured fo EIGRP.If I disable nat,EIGRP is working fine.Any ideas what could be the problem?


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
lejoe.thomas Thu, 01/15/2009 - 17:53
User Badges:
  • Silver, 250 points or more

Hi Emmanouel,

It would be helpful if you could post the running-configuration when EIGRP is configured.


Giuseppe Larosa Fri, 01/16/2009 - 05:43
User Badges:
  • Super Silver, 17500 points or more
  • Hall of Fame,

    Founding Member

Hello Emmanouel,

in a real world scenario a dynamic routing protocol is not used at a NAT device interface that is usually at a border router.

you can make EIGRP working by changing NAT configuration so that you can use an extended ACL.

access-list 101 deny eigrp any any

access-list 101 permit ip net wildcard any

route-map sel-nat

match ip address 101

ip nat inside source route-map sel-nat ...

What I don't understand is how OSPF works with NAT enabled.

Hope to help



This Discussion