Network question

[Pete Turnbull]

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[1] -- 
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).

[1] 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
						Network Manager
						University of York