GRE Tunnel flaps over multilink on one side only (EIGRP)

[gajanangavli]

Hi All,

We have 1 multilink (T1+T1) used as source for two GRE tunnels (build over EIGRP).These tunnels are flapping on one side only.

Telco tested both T1 , dont found any issue, we have expert checked config , dont found any issue.Can somebody help for such issue ?

1) No errors or drop on tunnels

2) Output drops & input errors observed on multilink

3) No multilink flaps during tunnel flaps

4) Both tunnels flaps at different time.

Attached tunnel & multilink config.

[John Blakley]

According to the log it looks like there's a K-value mismatch. If you only changed it on the remote sites and not all of the other neighbors, the adjacency won't come up. You can do a "sho ip protocol" on all routers and it will show you the k-values that you have set. The defautls are "metric weights 0 1 0 1 0 0". You can also, on R1, under the eigrp process type "default metric weights" to get them back to defaults. (This could also be set on the core and not the remote sites which is why I suggest looking at the weights with "show ip protocol"). I would just set them at the default unless you have a very good reason not to, but they have to match everywhere...

HTH,

John

[gajanangavli]

K-value mismatch is not the reason as the IOS of router send this message due to old version.

[gajanangavli]

Hi All,

After upgrading the hardware , issue got resolved.It is observed no input errors on mutilink.

Though output drops are still there , it is not causing tunnel to be down.

I was suspecting the buffer capacity of old router was the real issue...

Now tunnels are stable ..

Thanks