Which is more practical in production:MST vs Rapid PVST

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Aug 15th, 2009
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In my environment we use 802.1w.

From my studies I see that 802.1s actually incorporates 802.1w.

In practical terms, is people deploying MST successfully instead of using PVST+ or rapid PVST?

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Peter Paluch Sat, 08/15/2009 - 04:43
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Personally, I would go for MSTP. It is slightly more bandwidth efficient and I believe it saves a lot more of switch resources as it does not require maintaining separate STP instances and timers for each single VLAN like PVST/PVRST do. Also, MSTP is basically built upon RSTP and thus all the rapid convergence features are there. The possibility to map VLANs into MSTP instances provides you with a reasonable level of granularity when choosing the root bridge, root ports, and thereby allows for a fairly good load-balancing feature. Also the backward compatibility, at least in Cisco switches, is very good.

For me personally, in a larger network with a larger number of VLANs, the MSTP is highly preferred.

Best regards,


Jon Marshall Sat, 08/15/2009 - 08:26
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I agree with Peter in that if you have a large amount of vlans MST is the way to go. Having said that from my experience most of the networks i have come across have either been running PVST+ or rapid PVST and not MST.

I suspect the reason is because configuring rapid PVST is trivial whereas to configure MST takes a bit more thought, admittedly not a huge amount but still..


Peter Paluch Sat, 08/15/2009 - 10:06
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Hi Jon,

I agree completely with you. Running the RSTP is as easy as typing "span mode rapid" and that's it. Configuring a well-working MSTP is slightly more difficult and less experienced network administrators probably just stick to the saying "if it ain't broke, don't fix it". Also, the MSTP might not be supported on all switches, especially the low-end ones. Nevertheless, I think that the MSTP is very nicely designed and a lot of networks could benefit from it.

Best regards,



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