PVST to RapidPVST

[mikegrous]

Migrating from PVST to RapidPVST. Has anyone done this in an existing network? Will it cause STP to recalculate ie downtime?

[sachinraja]

Hi Mike

PVST and Rapid PVST are backward compatible..the bpdu version 2 is compatible with 802.1D STP..

you will not have any downtimes, but it is better to do it a with a scheduled change window (Just in case !)

have a look at this URL for more info on this migration:

http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_example09186a00807b0670.shtml

Hope this helps.. all the best

Raj

[Jon Marshall]

mikegrous wrote:
Migrating from PVST to RapidPVST. Has anyone done this in an existing network? Will it cause STP to recalculate ie downtime?

Yes, it will cause an STP reconvergence and Cisco recommend migrating in a scheduled downtime. To be honest pretty much most things to do with STP should be done that way. There is a doc for migrating from PVST+ to Rapid-PVST, good idea to have a read -

http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_example09186a00807b0670.shtml

Jon

[Ganesh Hariharan]

Migrating from PVST to RapidPVST. Has anyone done this in an existing network? Will it cause STP to recalculate ie downtime?

Hi,

Migration from PVST to RPVST will require a downtime as Rapid-PVST+ uses the same BPDU format as the 802.1D and it is backward compatible.Because of the backward compatibility, you can convert phase by phase. It is recommended to implement the changes in the scheduled maintenance window because the spanning tree reconfiguration disrupts the traffic flow.

Spanning Tree UplinkFast and BackboneFast features are PVST+ features. These are disabled when you enable rapid-PVST+ because those features are built within rapid-PVST+. Therefore, during the migration you can remove those commands. The configuration of the features such as PortFast, BPDUguard, BPDUfilter, root guard, and loopguard are applicable in rapid-PVST+ mode also The usage of these features are the same as in PVST+ mode. If you have already enabled these features in the PVST+ mode, the features remain active after the migration to rapid-PVST+ mode.

Hope to help

Ganesh.H

[mikegrous]

I did not think it will cause downtime as sadly most of our closets do not have redundant links. I suppose we revert to the saying "better safe than sorry".

Thanks for the input.

[Ganesh Hariharan]

I did not think it will cause
downtime as sadly most of our closets do not have redundant links. I
suppose we revert to the saying "better safe than sorry".
Thanks for the input.

Mike,

Downtime means stp will re converge and in that case available ports can become blocking ports for the traffic and as per the recommendation from cisco if in switching environment you are playing with configuration of  stp you should better to have downtime planned so that convergence time can be used in the down time to overcome the panic state.

Hope to help

Ganesh.H

[glen.grant]

    The downtime should not be that long , we are talking a spanning tree recalc which is maybe 50 seconds at it longest and probably less than that .  Do it off hours .   Most networks have windows in which changes are allowed to be made.