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45384
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Channel-group 1 mode on / desirable

acbenny
Level 1
Level 1

‎09-23-2007 08:17 AM - edited ‎03-03-2019 06:52 PM

Hi all,

As title, what's the difference ?

What condition I need to use on or desirable ?

thanks

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7 Replies 7

Kevin Dorrell
Level 10
Level 10

‎09-23-2007 08:52 AM

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

Edison Ortiz
Hall of Fame
Hall of Fame

‎09-23-2007 11:02 AM

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.

welcomeccie
Level 1
Level 1
In response to Edison Ortiz

‎10-31-2007 02:40 AM

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

0 Helpful

Edison Ortiz
Hall of Fame
Hall of Fame
In response to welcomeccie

‎10-31-2007 06:23 AM

Desirable at both ends...

0 Helpful

rgodden
Level 3
Level 3
In response to welcomeccie

‎10-31-2007 06:24 AM

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

0 Helpful

welcomeccie
Level 1
Level 1
In response to rgodden

‎10-31-2007 07:09 AM

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

0 Helpful

rgodden
Level 3
Level 3
In response to welcomeccie

‎10-31-2007 07:36 AM

about half way down the doc

under heading of cisco recommendations in bold type face

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