[c-nsp] Adding vlan to port-channel trunk causes port-channel toflap

[Jared Gillis]

"switchport trunk allowed vlan add 400" and I ran it under interface Port-Channel1.

Tony Varriale wrote:
> What was the command and where did you add it?
> 
> tv
> ----- Original Message ----- From: "Jared Gillis"
> <jared.a.gillis at gmail.com>
> To: <cisco-nsp at puck.nether.net>
> Sent: Thursday, January 07, 2010 2:23 PM
> Subject: [c-nsp] Adding vlan to port-channel trunk causes port-channel
> toflap
> 
> 
>> Hi all,
>>
>> I just ran into a strange problem on a 3750ME. I've got two gig ports
>> in an active LACP port-channel looking like this:
>>
>> interface GigabitEthernet1/0/1
>> switchport trunk encapsulation dot1q
>> switchport trunk allowed vlan 101,102,400,664,1000-2999
>> switchport mode trunk
>> speed 1000
>> duplex full
>> channel-group 1 mode active
>> end
>>
>> interface GigabitEthernet1/0/2
>> switchport trunk encapsulation dot1q
>> switchport trunk allowed vlan 101,102,400,664,1000-2999
>> switchport mode trunk
>> speed 1000
>> duplex full
>> channel-group 1 mode active
>> end
>>
>> interface Port-channel1
>> switchport trunk encapsulation dot1q
>> switchport trunk allowed vlan 101,102,400,664,1000-2999
>> switchport mode trunk
>> end
>>
>> When I added vlan 400 to the trunk allowed vlan list, one of the
>> underlying gig ports flapped, which caused the port-channel to flap as
>> well.
>> Jan  7 12:09:27.647 PST: %LINEPROTO-5-UPDOWN: Line protocol on
>> Interface GigabitEthernet1/0/1, changed state to down
>> Jan  7 12:09:27.656 PST: %LINEPROTO-5-UPDOWN: Line protocol on
>> Interface Port-channel1, changed state to down
>> Jan  7 12:09:28.654 PST: %LINK-3-UPDOWN: Interface Port-channel1,
>> changed state to down
>> Jan  7 12:09:31.464 PST: %LINEPROTO-5-UPDOWN: Line protocol on
>> Interface GigabitEthernet1/0/1, changed state to up
>> Jan  7 12:09:32.454 PST: %LINK-3-UPDOWN: Interface Port-channel1,
>> changed state to up
>> Jan  7 12:09:33.461 PST: %LINEPROTO-5-UPDOWN: Line protocol on
>> Interface Port-channel1, changed state to up
>> Jan  7 12:09:48.745 PST: %LINEPROTO-5-UPDOWN: Line protocol on
>> Interface Vlan400, changed state to up
>>
>> This definitely seems like something that should not happen. I'm
>> running Cisco IOS Software, C3750ME Software (C3750ME-I5K91-M),
>> Version 12.2(46)SE, RELEASE SOFTWARE (fc2).
>> Any thoughts on what I should be checking?
>>
>> --Jared
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> 
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