[c-nsp] Ethernet autonegotiation issue between Cat3560 and Cat2960

[Nick Hilliard]

On 22/11/2009 12:46, Juuso Lehtinen wrote:
> Any ideas what might be causing this. I wonder if I'm running into some kind
> of minimum cable length problem. Switches are sitting adjacent to each other
> in a rack and connected with very short cables (0.5m ~ 2 ft).

Are you sure you're using the correct cable type?  Either you should use a 
regular 568-B straight-thru cable, or else you should use a full GE 
crossover cable, which is wired like this:

1.	white/orange	->	white/green
2.	orange/white	->	green/white
3.	white/green	->	white/orange
4.	blue/white	->	brown/white
5.	white/blue	->	white/brown
6.	green/white	->	orange/white
7.	white/brown	->	white/blue
8.	brown/white	->	blue/white

Note that for a 100M cross-over, you only cross orange with green, but for 
GE, you need to cross blue with brown too.

Even if you're sure about the cabling, it's no harm to test it out with a 
decent cable tester.  Maybe there's something strange going on with the UTP 
termination plugs?

Cable length is only a problem where you use co-ax, as the co-axial cable 
medium can encourage all sorts of strange effects (signal reflection, 
timing problems, etc).

Nick