Etherchannel adding VLANS Best Practise?

phil.g.james · ‎04-14-2010

Could someone clarify the best practice to use when adding VLANS to Etherchannel connections on a pair of Cisco 6500 switch-routers running IOS.

Although the configuration shows the existing VLANS on any physical ports bound to the Etherchannel as well as the Etherchannel itself I understand that you should only add any new VLANS to the Portchannel using the switchport trunk allowed vlan add command and not add the VLANS to the physical ports bound to the Etherchannel as the configuration will add these automatically.

However during the change one side of the Etherchannel will have the new VLANS and one will not, until the VLANS are added to the second switch connected to the other side of the Etherchannel. Does this cause any instability on the Etherchannel? Would it be best to leave the new VLANS in a shutdown state until the Etherchannel VLAN additions have been made?

I need to implement this change without causing the Etherchannel to go down.

Would appreciate any advice.

Thanks

Phil

Jon Marshall · ‎04-14-2010

Phil

The key thing is to apply the command to the port-channel interface and not the individual links because if you apply it to the individual links they can drop out of the etherchannel.

You should be fine to apply it on one end and then on the other without affecting the portchannel but as with everything else if you are nervous about it best to do it out of hours.

Jon

phil.g.james · ‎04-14-2010

Thanks Jon and Giuslar. That has put my mind to rest, I will be doing this change out of hours just in case.

Giuseppe Larosa · ‎04-14-2010

Hello Phil,

once the bundle is up you should make changes only to the port-channel interface.

Attempting to add or remove Vlans to member links can even cause bridging loops (it happened twice in our customer network with C6500 involved)

The IOS will then add the Vlans to member links in the correct way and in a timely manner.

Hope to help

Giuseppe

bhisham84 · ‎04-14-2010

Do all settings on PO interface!!!!

Thanks/Bhisham