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

[Bill Wichers]

[snip]
> > ... and the context of *this* discussion is likely involving
PA-FE-TX's,
> > which are "quite old hardware", and cannot do any sort of autoneg.
> >
> True, so the ports should probably be nailed to full at both sides.

Correct, they are PA-FE-TX's. There are two such PAs in a VIP2-50, and
those are running the port channel. We use the 7507 as a DoS mitigator
since the CPU on the VIP can't handle typical DoS traffic very well and
effectively self-limits DoS traffic flow to around 20-30Mb/s or so. For
"normal" traffic it can do around 150ish Mb/s or so usually without
trouble. The packet size makes all the difference :-)

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...

  -Bill