Converting static L3 EtherChannel to LACP (mode active) on Catalyst 85

[Enabler]

Hello everyone,

I’m currently dealing with an EtherChannel issue between a Cisco Catalyst 8500 (IOS XE) router and a non-Cisco switch.

On the Catalyst side, the Port-Channel (channel-group 1) is configured as a static L3 EtherChannel, while on the switch side it’s configured as LACP. Because of this mismatch, we had to disable one physical link — otherwise, the entire Port-Channel would go down when both links were active.

I’m planning to correct the configuration by changing the existing static Port-Channel on the Catalyst to LACP (channel-group 1 mode active).

Question:
What are the implications of making this change on a live system?
Will the Port-Channel momentarily drop (causing a traffic interruption) when switching from static to LACP on the same channel-group, or will the transition be seamless if both sides are aligned to LACP?

Any insights or best practices from your experience would be greatly appreciated.

Thank you!

[Enes Simnica · Accepted solution]

gDay @Enabler (looks like will answer ur question too, and jump out of the laptop for today... LOL). 

U’re right to align both sides to LACP, that’s the best practice. However, when u change the EtherChannel mode from static (on) to LACP (active) on the Catalyst, the bundle will momentarily go down as the LACP negotiation starts. That means u’ll see a brief traffic interruption (a few seconds) while the links renegotiate and the port-channel comes back up. To minimize impact, schedule the change during a maintenance window or move traffic off temporarily. After both sides are set to LACP, you’ll have a more stable and fault-tolerant link.

(OR SHUT DOWN THE PORTS THAT WILL BE IN ETHERCHANNEL, CONFIGURE THE ETHERCHANNEL LACP OR PAGP, AND THEN USE THE #NO SHUT, SO LIKE THAT U WILL NOT HAVE ANY PROBLEM MY g)

hope it helps and PEACE, im out for real this time (for today LOOOL)

-Enes

[David Ruess]

Hello,

When changing the port from static to LACP it will go through the negotiation of the port channel and cause a temporary disruption in communications.

Best practice would be to submit something like an ASI (Authorized Service Interruption) to let everyone know it will be interrupted. Also best practice would be to make the change after duty hours in order to minimize customer impact.

-David

[Enabler]

Great answers! Thank you guys!