EIGRP downstream updates via DMVPN

[Ven Taylor]

We have several DMVPN-connected sites that are connected to our 2821 ISR pair.

They're all configured as eigrp stub connected summary.  Yesterday, a few of the sites went inaccessible, but the VPN tunnels were still up and running. 

Upon further investigation, we noticed that the remote sites stopped receiving routing updates from our 2821's.  As a quick fix, we added static routes to bring the sites back up.

Later that night, we removed the static routes and cleared the eigrp neighbors, hoping it would fix the problem.  When it didn't, we cleared them two more times.

Suddenly, the router lost all downstream adjacencies.  While we were adding statics to at least bring the sites back up, all of the adjacencies came back.

Does anyone have any idea why this would happen?

I've attached a drawing in case anyone wants to see how it's laid out.

Thanks!

Ven

[Rahul Kukreja]

Hi,

Here are few troubleshooting tips -

Remote Sites were not receiving the routes from the DMVPN Hub. Did you checked following -

Was there an entry for that subnet in the EIGRP topology table on Spoke Site
sh ip eigrp topology 10.10.10.0 255.255.255.0

If yes - What was the status of that route active or passive ? (although the probablity of SIA is very less as you have spokes configured as stub)

If no - was the same subnet there in the routing table on Hub ?

In DMVPN Environment - EIGRP Convergence may take some time depending on the number of spokes/routes

Also as all the neighbors are build over a single interface - please check following :

Bandwidth configured on Hub tunnel (as EIGRP by default will be able to send the updates upto 50%) if required - you may change the bandwidth-percent in EIGRP ..

- HTH
  Rahul

[Abzal]

Hi,

Enable EIGRP routing protocol and check with debug:

debug eigrp packets

Maybe you will see some errors.

Have you defined a static neighbor in the EIGRP routing process?

Try to increase hello and hold timers.

Have a look this link

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094613.shtml