Re: mst behaviour

Hi,

With MST, the STP state of an interface is per MST instance, NOT per VLAN.
When using MST and need to do VLAN filtering at the trunk level, you need to
ensure the VLAN filtering matches the VLAN-to-MST instance allocation,
otherwise you end up in such scenarios.

Regards,

Cristian Matei, 2 x CCIE #23684 (R&S/SC)
cmatei_at_INE.com<mailto:cmatei_at_INE.com>

Internetwork Expert, Inc.
http://www.INE.com<http://www.ine.com/>

On 13 Jun 2014, at 16:54, Rakesh M
<raaki.88_at_gmail.com<mailto:raaki.88_at_gmail.com>> wrote:

Hi,

Two switches are connected in my network with back-to-back port-channels.

port-channel 1 allows vlans 1-5 and port-channel 2 allows vlan 6 on both
the switches.

spanning-tree mode mst with instance 0 is configured globally.

What i find is by default, switch 2 has blocked the port-channel 1
interface for vlan 6.

i am slightly confused with this behavior , is it not based on vlans
per-interface , which should by default open Port-channel 1 for vlan 6 ?

when i place it in different instance, it comes into forwarding state
automatically

Thanks

Blogs and organic groups at http://www.ccie.net
Received on Fri Jun 13 2014 - 09:10:07 ART