interoperate between PVST+ or MST (802.1s) and CST (802.1d) region?

interoperate between PVST+ or MST (802.1s) and CST (802.1d) region?

Post by nit.. » Sun, 24 Jul 2005 13:59:42


I am confused on interoperate between PVST+ and CST (802.1d) region or
MST (802.1s) and CST (802.1d) region. Suppose I have access switch A
with 2 VLANs redundantly connected to 2 distribution/core switches, B
and C, in PVST+ or MST region. And I configure spanning tree to half of
VLANs forward on each uplink, such as VLAN 100 through switch B and
VLAN 200 through switch C. So, when I connect this region to CST
region, which's spanning tree topology to operate within the CST

Please advice me.

Thanks for advance,


1. MSTP RSTP - slow convergence in mixed environnement 802.1S 802.1W

Hi All,

My topology is easy, I have 2 core switches 3550 (running 802.1s 802.1w).
Both 3550 are connected via a trunk and all other ports are in access mode.
The distribution switches are dual attached (one link on each 3550)
I have 5 vlans and 4 instances. The others switches are 3524 and SMC.
802.1d is disabled in the SMC.

Everything is working fine, except the convergence time which is always
the old vlaues. I plan to migrate a large number of sites.

My question is:
Is it possible to run a mix 802.1d and 802.1w in differents instance ?
my assumption is that the switch detects 802.1d format and use this
protocol in all the instance ... Am I right ?

Any help will be appreciated

Philippe ~~~

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