How to track WAN interface and enable GRE tunnel when WAN down?

Unanswered Question
Oct 5th, 2009

I have one 3845 router each in site A and B. They have primary connection through WAN cloud and also GRE tunnel over IPSec in between as backup. WAN side has EIGRP and the tunnel has OSPF. Within each site, internal routing is OSPF too.

For some reason, I need to diable the tunnel when both site's WAN is up, and enable the tunnel when either site's WAN is down. How to configure object tracking to do it? I have not found a good reference.

Thanks a lot

I have this problem too.
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Jerry Ye Mon, 10/05/2009 - 13:09

You can configure backup interface on the serial interface. This will work if the WAN/Serial and the GRE/Tunnel is on the same router.

interface serialx/x/x

backup interface tunnel y

interface tunnel y



gwhuang5398 Thu, 10/08/2009 - 07:02

Thanks a lot. I'll try it. I once saw the "backup interface" command years ago. So I tried to find it in Cisco 12.4 command reference before I posted the question. But I didn't find it.

Would you please let me know where I can find the command? So I may be able to find a few different examples.

Thanks again



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