etherchannel

say you have 2 switches and your going to use ports 1 and 2 on both switches to create an ether channel.

Do you have to set encapsulation on both ends?

The example I have (lammles book) shows it on just one end.

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Comments

cdad2000

Yup, you have to set the trunking mode. There are different mode types like on, negotiate, and auto.

mikearama

Absolutely on both ends.

They don't have to match though... just be compatible. IE, one side could be set to desirable, while the other could be auto.

Netstudent

But never auto on both sides.

But can't you set switchport trunk encap negotiate? IN this case you would setup the trunks but the actual encapsulation could automatically negotiate? You would only set encapsualtion on one link partner?

mikearama

NS... what you describe is trunking, and you're right. What liven is asking about is etherchannel.

And you're right... auto and auto is a no-no, definately not compatible.

phreak

Yep, with auto on both sides they will never negotiate (according to the books).

Netstudent

Gotcha, I think the encapsulation question got me mixed up. Wasn't it you Mike that was asking a while back about port channel numbers not needing to match with link partners, but only on the local bundle? Some discussion with a boss maybe. I think that is a quirky little feature about ethernchannel.

mikearama

Yep, ya got me.

I frequently confuse the negotiation settins for portchannels with trunking... thank god for "?".

liven

Hey thanks everyone for the nice discussion.

Pash

Netstudent wrote:

But never auto on both sides.

I made that mistake a while back also before our infrastructure went live at customer site. As NS said, don't forget this, its crucial

There are some good cisco white papers on this, have a search when you have time.

Cheers,