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

[Tony Varriale]

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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