[c-nsp] Odd Etherchannel behavior between 7507 and cat 4006

[Alastair Johnson]

Bill Wichers wrote:
> I typically set both ends (router and switch) of these links to 100/full
> since I've seen weird autonegotiation problems before. This works just
> fine for individual FE links, but as soon as I bring up the Etherchannel
> group both member links on the router end drop back to "unknown duplex"
> (which the switch says is 100/half), and I can't figure out why my
> "full-duplex" config entry on each port magically disappears as soon as
> the Etherchannel group is brought up. That's the weird problem I'm
> trying to figure out...

My experience with 7500 and Etherchannel, particularly if it's across 
multiple PA is to just give up.  I was never able to keep it running 
reliably under 12.0S, whether the the other end was a C2924 or C4006.

Best case is it would work for a while, then some magic duplex problem 
would pop up and make it explode spectacularly - usually after a reload 
or an OIR or other CxBus restart, and occasionally after DCEF dying... 
Usually it would involve one end being in FDX, the other end being in 
HDX or no-duplex at all - despite both ends being configured for 100/Full.

I hope you have better luck, but I wouldn't count on it.  ISTR that 12.0 
mainline and some of the sub-tree variants (12.1E?) had slightly less 
problematic issues with it.

aj