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Rapid-PVST and uplinkfast interoperability

I have a distribution layer consisting of Cat 4506 switches running rapid-PVST. I have an old Cat 2924XL access switch running standard STP and uplinkfast. The access-switch is uplinked to two (adjacent) distribution switches.

It seems that when the primary uplink is interrupted for 3 seconds and then reconnected, the machines on the access switch lose contact with the rest of the network for 53 seconds. The access switch reports that the uplinkfast mechanism is working correctly.

Is there some interoperability issue between rapid-PVST and uplinkfast, e.g. the access switch not flooding its MAC addresses out the backup port correctly?

Kevin Dorrell



Re: Rapid-PVST and uplinkfast interoperability

is it happening only when primary uplink fails for 3 secs and come back immediately?

what about if primary uplink fails and does not come up for sometime, are machines losing connectivity in this case too?

maybe it is happening because when primary uplink fail, UplinkFast moves the original blocked port on backup uplink to the forwarding state without going through the listening and learning states and during this process primary link comes up so again UplinkFast moves to original port in primary uplink again due to which it is taking time for your network to re-converge.

rate me if it helps ...

Re: Rapid-PVST and uplinkfast interoperability

I was wondering about that as well, but after the interruption this morning I do not have enough brownie points left to be able to risk the experiment - at least not on that access switch. I would have to set up another non-production access switch to do the experiment.

Also, the timing is a bit bizarre. The clocks on all the switches are synchronised, but here is the apparent sequence of events:

10:42:46 Access switch "experiencing errors" on primary uplink

10:42:48 Primary distribution switch (root) reports link down to access switch

10:42:52 Primary distribution switch (root) reports link up to access switch

10:42:54 Server node on access switch reports apparent NIC failure (partner missing?)

10:43:03 Access switch reports moving secondary uplink to forwarding state

10:43:08 Access switch reports moving primary uplink to forwarding state

10:43:47 Server node on access switch recovers from error

It all seems to be happening in the wrong order.

I think I'll have to install another access switch and do the experiment.

Kevin Dorrell


Re: Rapid-PVST and uplinkfast interoperability

that will be good if another access switch can be placed and experiment can be done on that instead on production switch.

do update us with the result ... Good Luck..