nanog mailing list archives

Re: Cisco switch LACP + 802.1q


From: Randy Carpenter <rcarpen () network1 net>
Date: Thu, 29 Sep 2011 15:52:03 -0400 (EDT)


Thanks for all the suggestions.

I added the "switchport mode trunk" to the interfaces, and it did start working properly after a reload of the switch.
Before the reboot, it would not work.

-Randy


----- Original Message -----

I am tearing my hair out with an issue, and I hope someone can point
something out to me that I am missing.

I am setting up 2-port LACP sets on a Cisco 2960G-24TS-L, which then
need to be 802.1q trunk ports.

I have set it up as follows:

interface Port-channel1
  switchport mode trunk
!
interface Port-channel2
  switchport mode trunk
!
interface Port-channel3
  switchport mode trunk
!
interface Port-channel4
  switchport mode trunk
!
interface GigabitEthernet0/1
 channel-protocol lacp
 channel-group 1 mode active
!
interface GigabitEthernet0/2
 channel-protocol lacp
 channel-group 1 mode active
!
interface GigabitEthernet0/3
 channel-protocol lacp
 channel-group 2 mode active
!
interface GigabitEthernet0/4
 channel-protocol lacp
 channel-group 2 mode active
!
interface GigabitEthernet0/5
 channel-protocol lacp
 channel-group 3 mode active
!
interface GigabitEthernet0/6
 channel-protocol lacp
 channel-group 3 mode active
!
interface GigabitEthernet0/7
 switchport mode trunk
 channel-protocol lacp
 channel-group 4 mode active
!
interface GigabitEthernet0/8
 switchport mode trunk
 channel-protocol lacp
 channel-group 4 mode active


The problem is that after some period of time (sometimes minutes,
sometimes hours), port-channel1 loses the "switchport mode trunk"

It just disappears from the config.  If I try to put it back, it adds
"switchport mode trunk" to the member ports (Gi0/1, Gi0/2) as well,
which does not work. I have to tear it all out and start again. It
will then work for a while again.

port-channel2 and port-channel3 are not in use yet, but port-channel4
is, and works just fine.

It is running IOS 15.0(1)SE. It was running 12.2 before, and it was
doing the same thing, so I upgraded it to the latest available.

What could be the issue?

thanks,
-Randy



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