pete at dunnington.plus.com
Tue Jan 2 05:38:27 CST 2007
Doc Shipley wrote:
> Sridhar Ayengar wrote:
>> How come there's no 1000Mbps half/full settings?
Because there's no such thing as half duplex Gigabit Ethernet. The
standard only permits 1000 full (but it does allow autonegotiation).
> The performance
>> problems I'm having are when I'm connecting to a gigabit network.
>> Will setting to 1000Mbps auto help?
> The biggest blessing of gigabit ethernet isn't 1000bps, it's a decent
> auto-negotiation standard. auto/auto is a hell of a lot more reliable
> between gigabit devices than 10/100 or 10Mbit, so your situation is a
> little odd.
I'm not sure I completely agree. The standard was changed some time
ago, and where once the default was 1000 full it is now 1000 auto. The
end result of course is always 1000 Mb/s full duplex but one setting
allows for (and should insist upon) negotiation and the other doesn't.
That's a problem with some things -- we have sporadic problems with
Suns, some of which seem to do it one way and some the other --
because if you pick the wrong option you get no traffic at all (as
happened recently when a telco replaced a piece of kit on one of our
Gigabit WAN links).
 I don't know if this is a hardware dependency or a Solaris
version/patch issue, because we (the network group) have no control over
the Suns, which are run by our Systems Group, and are, um, "a mixed bag".
> It sounds like XP has your adapter forced to something Not Right.
I agree, but it could also be a negotiation problem; we saw a lot of
that about a year ago on our student network, with Intel-chipset Gigabit
interfaces in certain new laptops connecting to 10/100 ports (other
chipsets worked fine). Typically the laptops got a connection, but an
extremely slow or erratic one. The workaround was to fix the adaptor
speed/duplex, but IIRC a recent driver update eventually improved things.
Pete Peter Turnbull
University of York
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