Network question

[Doc Shipley]

Pete Turnbull wrote:
> 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).

   I certainly wouldn't claim that the standard's perfect, much less 
perfectly implemented....

   I really just meant that with gigabit, as opposed to 10/100, it's 
more likely a software problem than hardware autonegotiation.

> [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".

   Given my experience with SPARCs in this I'd say it's hardware.  I 
have an e250 whose onboard HME has to be forced with one of my switches, 
and won't make a link at all with another unless it's set auto/auto.

> 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.

   Yup.  I have a dual-Xeon board right here with 2 onboard 1000Mbps 
ports.  It attaches to a cheap AOpen switch, and won't link on boot.  I 
have to plug the cable into a 10/100 hub, let it negotiate, then plug it 
back into the gigE switch, where it will then DTRT.  'Splain *that* 
bizness, please....

   Makes PXE booting a little problematic.  ;)



	Doc