Cisco Etherchannel


When configuring Etherchannel between 2 3750 devices which protocol and mode should I use?
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Don JohnstonConnect With a Mentor InstructorCommented:
PAgP or LACP. As long as you use the same protocol on each end, they're both about the same.

I'm partial to PAgP in Desirable mode.
JFrederick29Connect With a Mentor Commented:
I myself get paranoid about "negotiation" so I always set it to "on" on both ends.
Don JohnstonInstructorCommented:
I agree about negotiation... Except here. The problem with "on" where etherchannel is concerned is that if there's a problem, "on" may not errdisable the ports. Then you've got yourself a good old fashioned broadcast storm. Desirable mode is better at dealing with this.
grsteedConnect With a Mentor Commented:
I've also seen the problem that donjohnston mentions with "on" mode in PAgP, so now I use "desirable"  

I also had one recently where the link (between a 6913 and an HP Blade Chassis w/built-in Cisco switches, 3020?) where the links set for desirable wouldn't come up because they were errdisabled by udld. A check of another working chassis showed that udld wasn't enabled. When I set it to disable, the links came up.

Don JohnstonInstructorCommented:
Yep. That's what I tell people in class: With etherchannel, EVERYTHING must match. :-)
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