Dialer watch on underutilized lines

borek · ‎07-25-2003

When primary line on a router fails, dialer watch causes backup to dial out. But: when there is no traffic on the line, the backup line will go eventually down (idle-timeout kicks in) - immediately after the backup line goes down dialer watch brings it up again. This will happen continuously until there is traffic or the primary line goes up. Is there way to avoid this?

rais · ‎07-25-2003

You can either increase your dialer idle time or your can benefit from dialer watch connect delay feature.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide09186a00800e9753.html

Thanks.

borek · ‎07-25-2003

But does not "connect delay" increase time without any connectivity at all? When I set connect delay to say, 120 secs, these 120 secs there will be no connectivity. And in fact, both solutions only mitigate the problem, they do not solve it.

One has to think why the dialer watch doesn't work just like "backup interface" - it is putting the backup interface to "standby mode" and only enabling it in time specified routes are not seen in routing table. Then you could use either dynamic protocol to keep the line up, or even OSPF demand circuit, to dial it only when necessary.

d-rivers · ‎07-28-2003

I've seen this problem with certain versions of code. Dialer-watch is supposed to check for the existence of the route(s) being watched if the idle-timeout is reached, and if the route is still missing the call remains up for another idle-time period.