Static routes & Sub-interfaces

[robyn]

Has anyone heard of a problem with pointing a static route to an out going sub-interface? I have a client with a 7204VXR with an ATM port adapter (PA-A3-OC3SMI) configured with sub-interfaces. The static route looks like this (for example): ip route 10.3.30.0 255.255.255.0 ATM2/0.6. There are other static routes configured for the purpose of forcing certian traffic over specific PVCs. The traffic flow works fine for about an hour, then the static routes start to fail -- trace routes show the traffic crossing from the PVC it should be taking to another.

Any ideas?

[Richard Burts]

The situation with static routes pointed at interfaces and subinterfaces is different depending on whether the interface or subinterface is point to point or is multi point. If the inteface is point to point then the operation of the static route is simple: there is no ambiguity about to whom or over which virtual circuit the data is to be sent and the data is sent.

If the interface or subinterface is multipoint then the operation of the static route is more complicated because there must be some mechanism that determines to which neighbor or over which virtual circuit the data will be sent.

It is not clear in your question whether these are point to point or multipoint subinterfaces. But I am going to assume that they are multipoint and that the mapping of address to PVC that was in place when the route was defined has changed when the static route stops working. Is there any chance of changing the static route and instead of pointing to the subinterface have it point to the next hop address of the neighbor to whom it should be sent?

HTH

Rick

[robyn]

The sub-interfaces/PVCs are point to point. I'll suggest that my customer point the static route to the next hop, but I'm still wondering why pointing it to an outgoing sub-interface didn't work.