I have had this happen on a couple installs recently and am not clear why (but I suspect something with auto smart ports).
In the most recent example I have a SF300-28P and a SF300-52P connected via fiber on gi4 of each switch. Config is very simple. VLAN 100 for voice and native VLAN 1 for data. on gig4 of each switch I did switchport trunk allowed vlan add 100
and nothing else. Show run would result in:
interface gigabitethernet4
spanning-tree link-type point-to-point
macro description switch
switchport trunk allowed vlan add 100
!next command is internal.
macro auto smartport dynamic_type switch
The switch lost power and all config came back except switchport trunk allowed vlan add 100 was missing and therefor IP phones on that switch went down.
I am 99.9% sure I had done copy run start before the power outage. Assuming that is accurate is there a reason this would happen? Should I be disabling auto smart ports on these switches? They seem to sometimes also cause grief with IP phones for no apparent reason.
thanks in advance,
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