Symptom
DAD links on a stackwise virtual pair are put into err-disable due to "spanning-tree portfast bpduguard" default configuration.
Conditions
Following global configurations (or equivalent) are present:
spanning-tree portfast bpduguard default
spanning-tree portfast default
This can happen upon reload of any member of a stackwise virtual setup.
This is a day 1 issue which can potentially affect any Cat9K platform running stackwise virtual setup.
Workaround
1) Do not configure "spanning-tree portfast bpduguard default" and instead configure it on a per port basis
Further Problem Description
The issue is a day 1 issue that can potentially affect any stackwise virtual running platform and is due to a racing condition during boot, where STP protocol is initialised on an interface which belongs to a DAD link group.
These protocols, under normal conditions, should not be initiated on these interfaces.
