ISDN IDLE TIME OUT NOT WORKING IN CASE OF GRE TUNNEL

[vivek_mohta]

In case of the LL with ISDN backup conectivity. The Idle time out of the ISDN is not taking into affect even though when there is no traffic .A tunnel is created and the traffic is flowing via the tunel in case of ISDN backup. Does the tunnel creates any traffic on its own to establish the tunnel connectivity.

When debug dialer packets was applied it showed traffic with souce as Tunnel Souce and destination IP as PE Router.

How can we overcome this under this scenrio .Will an extended access list mentioning the Intersting traffic only from the customer LAN pool only triger the ISDN help to overcome this issue.

[Richard Burts]

Generally there is not any traffic generated by the tunnel itself to establish tunnel connectivity. There are some features, most especially the recent addition of tunnel keepalives, which would generate periodic traffic which would look like interesting traffic to the ISDN timeout.

I am not clear from your message whether it is a simple GRE tunnel or whether you have something like IPSec running through the tunnel. If you do have something like IPSec running in the tunnel it might have its own keepalives which would become interesting traffic in the GRE tunnel.

Another possibility to consider is whether you are running any dynamic routing protocols over the tunnel. The HELLO messages from OSPF or EIGRP would look like interesting traffic to the ISDN timer.

Perhaps you can be more specific about how the tunnel is configured and what is running over it and we might be able to find an answer for you.

HTH

Rick

[vivek_mohta]

I am using a simple GRE Tunnel and their is no routing protocol running in the CPE . Its a static routing where the default route is pointing towards tunnel and the tunnel destination is poitng towards serial and higher metric towards BRI.

I have tried by removing the Keep Alive from the tunnel .I had shut down the Ethernet to check whether the Idle time out was working or not.

when the idle time out expires the BRI disconeects and then after 5-10 seconds it reconnects and the debug shows the traffic is generated by the Tunnel source and its destination is the Tunnel Destination IP.

[Richard Burts]

It might be helpful at this point if you would post some additional information: output from show inteface tunnel, output from show ip protocol, configuration of the tunnel.

HTH

Rick