Adding vlan to a trunk in port channel on cat 6500 switch with CAT OS

[anand ukey]

Hi All,

  I need some urgent assistance with adding a vlan to the trunks bundled in port channel. I know how to add vlans to a port channel with cisco IOS but with CAT OS i'm a bit nervous.

I have 2 ports bundled to form ether channel in switch which is running CAT OS. There are already few vlans allowed in the trunk of each interface. now I need to add one more vlan.

For Example:-

vlan 135 needs to be added in addtion to the existing vlans.

clear trunk1/2 1-112,115,117-134,136-4094

set trunk 1/2 on dot1q 113-114,116,135

and similarly on the 2nd interface

so if I add vlan135 to the trunk one after another will it cause any service disruption?

Please Help.

Thanks in Advance

[rsimoni]

Hi Anand,

vlan 135 needs to be added in addtion to the existing vlans.
clear trunk1/2 1-112,115,117-134,136-4094
set trunk 1/2 on dot1q 113-114,116,135

Vlan 135 is already in the trunk!

set trunk 1/2 on dot1q 113-114,116,135

In general the command to add a vlan to an existing trunk is

set trunk 1/2 on dot1q 140
 

While you add or remove vlans there is no impact for the other vlans carried in the trunk (beside the ones you are removing, obviously)

check also this out

http://topic-rtp.cisco.com/taccc/lanswitching_K11881886.html

Please rate and close the thread if helpful

Riccardo

[anand ukey]

Ricardo, Thank you for your reply.

  Since i'm changing the config one port at a time (since the port channel includes 2 ports) and this port channel is the only uplink to the distribution.

will it cause any impact/outage or will i loose connectivity since i'm configuring it remotely?

Thanks

[rsimoni · Accepted solution]

Hi Anand,

yes, the EC might go down as also indicated in the configuration guide:

"An EtherChannel supports the same allowed range of VLANs on all the ports in a trunking EtherChannel. If the allowed range of VLANs is not the same for a port list, the ports do not form an EtherChannel even when set to the auto or desirable mode with the set port channel command."

http://www.cisco.com/en/US/partner/docs/switches/lan/catalyst6500/catos/8.x/configuration/guide/channel.html#wp1026624

consider for the worst case scenario a short manteincance window for the change. If you are fast enough the EC might not 'notice' the change and stay up, but it might go down.

Riccardo