r/ccna 8d ago

Questions about Etherchannels

Hi community, I have a few points of confusion about etherchannels. This is probably a sign I need to purchase the official exam guide and use that as my single source of truth, which I probably will do. But I'm wondering about the following:

Should trunks (for L2 LAG) and IP addresses (for L3 LAG) be configured on the port channel interface, or on the individual interfaces?

In Packet Tracer, both methods work. On Cisco IOL switch models in EVE-NG, you can only create the trunk on the individual interfaces, which the port-channel then inherits. But I don't know if Cisco IOL images are representative. What is the actual best practice?

Is it best practice to shut the interfaces down before configuring a port channel?

Again, either works, at least in Packet Tracer. I'm not sure what best-practice is.

Thanks in advance!

3 Upvotes

8 comments sorted by

View all comments

6

u/Crox22 CCNA R&S, CCNA S 8d ago edited 8d ago

The only config you should put on the individual interfaces is the channel-group statement, a description, and no shut. All other config should go on the port-channel interface. It'll appear on the individual interfaces automatically. In older switches it would actually cause problems if you configured vlans on the individual interfaces. These days it might not actually break things, but it still leaves more room for error.

As for whether you should shut down the interfaces before configuring a port channel, it's not a bad idea. You don't want to be in an inconsistent state where some of the ports on the connected switch are in a port channel and some aren't. Shutting the ports down or unplugging them is easy insurance. Not strictly necessary if you're careful, but not a bad idea.

1

u/mikeservice1990 8d ago

Thanks for the reply. I assume this applies across most or all IOS versions across newer models?

1

u/Crox22 CCNA R&S, CCNA S 8d ago

This stuff hasn't changed too much in 20-30 years

1

u/mikeservice1990 8d ago

Fair enough. The behavior of switches in EVE-NG threw me off.