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Community Member

Channel-group 1 mode on / desirable

Hi all,

As title, what's the difference ?

What condition I need to use on or desirable ?

thanks

7 REPLIES

Re: Channel-group 1 mode on / desirable

on means force channelling on, but do not negotiate with the other side.

desirable means try and negotiate with the other side, and if he agrees, then enable the channel.

If you have on on one side and desirable on the other, then it will not form a channel because no negotiation will take place. In fact, it is likel?y to cause problems because one side will think it's channelling, and the other side will think it's not.

Use on when you are talking to a switch that does not understand negotiation but which has channel configured on, or if you want to bypass the negotiation to make the link come up quicker.

Kevin Dorrell

Luxembourg

Hall of Fame Super Bronze

Re: Channel-group 1 mode on / desirable

In addition to Kevin's post, you often use 'on' when the device in the remote end does not support etherchanneling negotiation. You often see this configuration when channeling server ports or non-cisco devices. The channeling mode on both devices must be 'on/on' in order to work.

The desirable option is often used between Cisco switches. Desirable employs the PAgP protocol which is Cisco proprietary. When you use Desirable, the remote end must be set to Desirable or Auto. Those are the only compatible settings (Desirable/Desirable or Desirable/Auto).

There is also another channeling option, LACP. LACP is industry standard and it's supported widely on most 3rd party switches and certain server NICs. LACP uses the Active/Active or Active/Passive modes.

Community Member

Re: Channel-group 1 mode on / desirable

So what is the recommended mode on or desirable if there are 2 cisco switches?

Hall of Fame Super Bronze

Re: Channel-group 1 mode on / desirable

Desirable at both ends...

Community Member

Re: Channel-group 1 mode on / desirable

Cisco Recommendations

Cisco recommends that you enable PAgP on channel connections between Cisco switches

http://www.cisco.com/en/US/products/hw/switches/ps700/products_white_paper09186a00801b49a4.shtml#cg6

Desirable, Desirable

Community Member

Re: Channel-group 1 mode on / desirable

Thank you ver much for your reply but where can i find that recommendation in the doc ?

Community Member

Re: Channel-group 1 mode on / desirable

about half way down the doc

under heading of cisco recommendations in bold type face

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