EIGRP Fail over

[ciscoben2009]

Hi All

We currently have a site to site link between two of our offices and a backup VPN via the internet

the primary site to site link is connect to a primary router on each site and the VPN back is connected to a backup router on each site

If the primary link fails there is delay on the traffic moving over the backup link i think this is due to the hold timer waiting for the eigrp adjancey to fail

Is there anyone to speed this up i have read eigrp should do sub second fail over i know i am doing something wrong

Any help would be great

Thanks

Ben

[Jon Marshall]

Ben

Can you confirm that the backup router in London is actually getting routes from Sheffield ?

Jon

[ciscoben2009]

It is yes have checked the back up routes does prefer the routes from the primary router to sheffield but that because the link is 10MB compare to a 8MB back up

the primary route both ends wont add anything to there topology database from the back up routers

thanks

Ben

[Jon Marshall]

Ben

Just to clarify, the output you have posted is from the command "sh ip eigrp top all-links" and not just "sh ip eigrp top" isn't t ?

If the routes are not being installed it suggests the metric is being reported as unreachable ie. the metric is too large.

Are you manipulating the metrics anywhere with offset-lists for example ?

Jon

[ciscoben2009]

correct it is a all links and there is no maniplulating with of set lists

I have lower the delay from 500000 to 200 on the gre tunnell and up the bandwidth from 8 to 10000 encase it was that but no change

It is odd!

thanks

Ben

[Jon Marshall · Accepted solution]

Ben

I think you are going to have to do some debugging of eigrp to work out what is going on. You need to see the updates going between the backup and primary routers. Obviously this will have an impact on the router so do it during a quiet time if possible.

if your networks are summarisable from each site then there are alternatives ie.

1) don't send EIGRP updates down the VPN tunnel but instead use a floating static on each primary router pointing to it's relevant VPN backup router which will only kick in if the routes down the main link get lost

or

2) advertise a summary route down the VPN link only which should not conflict with any of the more specific routes and so hopefully should be installed in the routing table of the primary routers. But with the problem you are seeing this may or may not work.

But it would be good to try and work out why these routes are not installing.

Jon

[ciscoben2009]

Thanks for the help Jon will try some debugs and let you know

either way

thanks

Ben