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New Member

Frame Relay PVC State Changes

Probably really obvious this, but heres the scenario..

I've got two 3620's connecting into a frame relay network, both running IOS version 12.1(17). I've got the dlci's mapped onto a sub interface, when I shut the sub interface the pvc state ( using sh frame pvc ) remains active why ?? I would expect it to go inactive as the main interface is still up and responding to LMI messages, and if I shut this the pvc state changes to deleted as expected, so why doesnt the pvc state change when the sub interface that it is mapped to is admin shut. LMI type is cisco, frame relay lmi is nortel vendorforum these are compatable.frame encapulation is ietf

answers on a postcard.....

Thanks

Mike

1 ACCEPTED SOLUTION

Accepted Solutions
New Member

Re: Frame Relay PVC State Changes

Mike,

the pvc remains active, because the pvc is still active in the frame relay network. Within the LMI protocol the router asks the frame relay node

( default every 60 seconds) for a full status of all PVCs and the frame relay

node just replies to this requests. Check this with the "debug frame-relay lmi" command.

The router has no possibility to inform the frame relay switch that the pvc

is down, because the lmi intf-type is set per default to dte. Only in the case

you use frame relay in a router back to back scenario with one router configured as a frame relay switch you will see the pvc status to change to

inactive when you shut down the subinterface on the router which acts

as a frame relay switch:

Hope this answers your question.

regards Ulrich Marzoli

www.netaid.de

2 REPLIES
New Member

Re: Frame Relay PVC State Changes

Mike,

the pvc remains active, because the pvc is still active in the frame relay network. Within the LMI protocol the router asks the frame relay node

( default every 60 seconds) for a full status of all PVCs and the frame relay

node just replies to this requests. Check this with the "debug frame-relay lmi" command.

The router has no possibility to inform the frame relay switch that the pvc

is down, because the lmi intf-type is set per default to dte. Only in the case

you use frame relay in a router back to back scenario with one router configured as a frame relay switch you will see the pvc status to change to

inactive when you shut down the subinterface on the router which acts

as a frame relay switch:

Hope this answers your question.

regards Ulrich Marzoli

www.netaid.de

New Member

Re: Frame Relay PVC State Changes

Ulrich,

Thanks for reply.

Basically this seems very straight forward that aslong as the lmi is up at both ends of the circuit the pvc will always show that it is up. Which seems a shame if using sub interfaces.

All the best

Mike

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