Hello,
I have configured a remote office using a Linksys VPN router with cable modem connecting back to our main office to a 1720 with an IPSEC 3DES tunnel. That is configured and working fine.
Beyond the two routers on each end in an additional router running IP/PLUS 12.2.8T. These routers are endpoints for GRE tunnels extending through the VPN tunnel. Each is configured with EIGRP. I have configured floating static routes on the remote router to facilitate ISDN backup to the main internal router, thus bypassing the GRE/IPSEC tunnel.
Everything is working as expected except that for some reason, my ISDN backup comes up prematurely without the primary line failing. I have confirmed that the EIGRP routes are disappearing on the remote end and thus the floating static brings up the isdn interface. The problem is that the logs indicate that the GRE tunnel interface never goes down, nor does the IPSEC tunnel either.
So why do the EIGRP routes mysteriously disappear, and only occasionally?
Could it be bandwidth saturation causing the delay of hello packets? That's my first thought, so I added the EIGRP hold-time command to increase the hold time to 45 seconds, but it didn't seem to make a difference or even affect it one way or the other. I know that the bandwidth statement affects the behavior of EIGRP over certain links. Can someone with EIGRP and GRE experience please make some more suggestions as a possible cure or even a place to begin debugging the problem. I would think if the problem were in the Cable modem/ISP, the IPSEC tunnel would collapse and so would the GRE tunnel.
Thanks for any help you can provide.
Billy
