[c-nsp] WS-X6748-GE-TX auto negotiation anomalies

[Will Hargrave]

On 08/04/10 17:42, Jason Lixfeld wrote:

> 'speed auto 10' would be an acceptable 6748 workaround, but even that
> behaves differently on the 6748 vs ME/3550.  The 6748 needs two speeds for
> speed auto ie:  speed auto 10 100 whereas the ME/3550 need only one ie:
> speed auto 10

Right, so what you are doing here are two distinct things - it's confusing
because of the disparate platforms:

Case A: changing the capabilities advertised using autoneg to only advertise
10mbit speed

Case B: turning off autoneg altogether.

In the case of B, without autoneg visible the remote end cannot sense duplex
(it can of course sense speed) and thus you get the correct speed but half duplex.

This is because Cisco didn't put enough twiddly knobs in the CLI on 6500 to
configure what you want. I agree it is annoying, lots of cheaper devices allow
you to independently:

a. turn on or off autoneg
b. turn on or off auto-mdix
c. select capabilities (speed, duplex, flow control) advertised using autoneg
d. select capabilities (speed, duplex, flow control) actually accepted

I feel your pain; the lack of configurability invariably leads to people just
turning off autoneg altogether, which is worse.

Will