Cisco Etherchannel

Posted on 2007-10-07
Last Modified: 2012-07-17

When configuring Etherchannel between 2 3750 devices which protocol and mode should I use?
Question by:Ciderspine
    LVL 50

    Accepted Solution

    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.
    LVL 43

    Assisted Solution

    I myself get paranoid about "negotiation" so I always set it to "on" on both ends.
    LVL 50

    Expert Comment

    by:Don Johnston
    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.
    LVL 11

    Assisted Solution

    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.

    LVL 50

    Expert Comment

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

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