Cell Relay Archive

[Patrick Hurley <patrick.hurley@wco.com>]

marc langston wrote:
> 
> I have recently been in a discussion concerning how ATM would handle the
> case of a PVC/VCC reconnect in the event of an intermediate switch
> outage.  For example, if the PVC travelled from access switch A to
> intermediate switch B to intermediate switch C to access switch D, and
> switch B were to fail, what would happen to the PVC?  Would it "regrow,"
> or is that PVC just plain down?
> 
> I have always been under the impression that ATM "the protocol" does not
> have any way to "rebuild" the PVC in the event of a switch outage.  (If
> there was a trunk outage, SONET would re-route to the switch.)  But my
> recent discussions have brought up points to the tune of "How can you
> have a modern transport protocol that isn't able to recover from that
> sort of outage?"
> 
> I haven't been able to find any information in ATM books about what
> happens in outage situations, so thought of asking the question here.
> Any thoughts?
> 
> Thanks,
> marc

Soft PVCs will reroute with an intermediate switch failure.  Cisco
Stratacom switches have this functionality.   Also, PNNI will support
the same type of rerouting with crankback.
-- 
Patrick Hurley
Sr. Network Consulting Engineer
Kaiser Permanente Health Plan