[178339] in North American Network Operators' Group
Re: Multiple Spanning Tree Instance 0
daemon@ATHENA.MIT.EDU (Chris Marget)
Fri Feb 27 06:03:27 2015
X-Original-To: nanog@nanog.org
In-Reply-To: <49EE1A35457387418410F97564A3752B013673ECC2@MSG6.westman.int>
Date: Fri, 27 Feb 2015 06:03:24 -0500
From: Chris Marget <chris@marget.com>
To: Graham Johnston <johnstong@westmancom.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On Wed, Feb 25, 2015 at 4:09 PM, Graham Johnston <johnstong@westmancom.com>
wrote:
> We are planning a migration from Rapid PVST+ to Multiple Spanning Tree to
> better support a mixed vendor environment. My question today is about MST
> Instance 0. In practice do you map any VLANs there other than VLAN 1?
I'd hoped to see some responses to this thread because I recently had some
awkward moments with a vendor after discovering that their switch wouldn't
allow me to map VLANs to STP instances in an arbitrary manner. I took the
position that the implementation was faulty, their position was more along
the lines of "Well, why would you want to do that anyway?"
Addressing the question directly, I know of two switching platforms which
force the operator to map VLANs other than 1 into instance 0.
Some Broadcom FASTPATH based platforms fail to mention VLAN 4094 in any
'show spanning-tree' commands, but always maps it to instance 0.
The implementation of MST available on Cumulus Linux only supports instance
0, maps all VLANs there. My Cumulus experience is a bit dated, this may
have changed in the last year.
/chris
