I know I can configure any etherchannel on the command line but I guess I'm too stupid to do it via a friendly www/java interface.

The question came from a customer because he read it was possible.

In the topology manager you can select a link, right click and select "create etherchannel". It offers 1 or more links, select any combination of it, select create and you get an error that the admin priority value is not allowed, the spanning tree could need a new calculation or the operational mode of the trunk is not valid to be chancged.

It's a default error which I get for all links which could do etherchannel. These were 3560 routers. I recreated it in my the lab, fresh CW install, 2 switches, a 2950 and a 2940. The 2950 couldn't do DTP so I had to configure it statically. I got the same error.

The problem is that it's true that spanning tree needs a recalculation but the way I see it it would ALWAYS need a recalculation else both switches would not be in the spanning tree domain. (Unless you deconfigure spanning tree everywhere.)

There is very little documentation what the exact prerequisites are. There is also no usable error message except (probably) a static one.

Now the customer asks me why he could configure it via the CMS and not via CiscoWorks.

An experience exchange regarding this issue would be highly appreciated.

-Danny