Migration from PVST to RSTP mode in switches

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Jul 30th, 2008
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I am planning to Migrate STP mode from PVST TO RSTP in cisco 2950/3548 switches( ALL the switches are access Switches)

Apart from the below link, can any body suggest precautions and mesures that i have to

take before implementing the change.


2) i will start with access switches, will be there be any down time in the network???

any body can shre there experience with me

Please suggest me the list of actions

Thanks & reagrds


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Rik Guyler Wed, 07/30/2008 - 04:48
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I think you better re-read the requirements for Rapid-PVST+. 3500XL series switches don't support it so connected devices running Rapid-PVST+ will fall back to PVST mode anyway. In other words the upgrade will do nothing for you so long as you have the 3548XL switches in there.

As for the downtime question, there will likely be a disruption since you would be building an all new tree with the different STP version.

UCBNOCWAN Wed, 07/30/2008 - 17:43
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Thanks very much for your inputs, yes i am aware that 3500XL wont support RSTP, i am migrating 2950 switches from PVST to RSTP, please advice on the same



UCBNOCWAN Mon, 08/04/2008 - 04:05
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I am doing migration from PVST to RSTP for about 50 switches, can any one tell me how much down time will be there on network


Francois Tallet Mon, 08/04/2008 - 09:20
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Depends on so many factors that no one can answer this I'm afraid.

If the bridges you are migrating are just access bridges and the rest of the network is running rapid-pvst, the host attached to the switch you are migrating will experience some traffic disruption for few seconds probably.

If the distribution is running PVST, add a good 30 seconds to that (and be careful about how inefficient stp/rstp interaction is).

If the bridge you are upgrading is not an access switch, meaning that there are other bridges downstream connected to it, it becomes much more complex to evaluate how long it will take. What is your expectation?



UCBNOCWAN Tue, 08/05/2008 - 00:58
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Hi ftallet,

Thanks very much for the reply.

the Switches that i am migrating are access switches



marmanet Tue, 08/05/2008 - 07:26
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i would suggest you to take a moment to upgrade old 2950 switches before migrating (lot af bug corrected) don't use 2950 prior to 12.1(22)EA1 in RSTP.

For information, last IOS version of 2950 is 12.1(22)EA12.

Latest IOS for 3500XL is 12.0(5)WC17 but no RSTP, STP will be used with the 3500XL (that's not a problem).


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