[plug] gigabit lan

Kev kdownes at tpg.com.au
Fri Jan 11 12:10:39 WST 2008

regfrem at connect.net.au wrote:
> Hi Kev,
> Is all the cabling correctly installed and terminated? If you have poor
> termination or a source of interference you will not achieve maximum
> transfer rate. EMF / RFI.

Yes it's all been checked and checked again.  The 2 machines I'm 
experimenting with are right here on my desk.  I've used CO cleaner on 
all the connections and I now have cat6 cables in use.  The cables are 
2m long.  The only crossover cable I can find is cat5E, but that seems, 
so far, to make no difference.  EMF/RFI did cross my mind, but 
implementing some makeshift cabling, /well/ clear of all other cables 
negates that I believe.

> If you try a test PC - PC with a cross-over cable make sure that the
> NICs are set to a speed rather than 'auto'. I've seen instances where
> the auto sensing doesn't work to well and the speed 'hunts'.

This could be a clue, and I'll get around to trying it in the next day 
or 2.  The speed /does/ hunt - between about 10Mbyte/sec and 
25Mbyte/sec.  The crossover cable gave identical results to going 
through the switch.

The way it looks right now is:  Marvell gb nic -> cat6 cable -> gb 
switch -> cat6 cable -> nVidia gb nic  -  and visa versa of course.

> Cat 6 has better noise rejection than Cat 5 and 5E.

Cat6 now in use - no change in performance.

One previous suggestion might be a problem though, and that's the pci 
bus.  Both machines have AGP graphics (pci bus), onboard sound (pci bus) 
and all the hard drives are PATA, which I /think/ is on the pci bus 
also, isn't it(?).  The on-board nics are also on the pci bus I 
believe.  The mobo with the nVidia nic is a LanParty nf3 Ultra-D with an 
AMD Athlon64 3200+ CPU and 2gig of RAM.  The other machine (Marvell nic) 
has an Asus_A7N8X-E_Deluxe mobo with an AMD Athlon 2500+ CPU and 1gig of 

You've all been very forthcoming with helpful info, which will take me a 
while to work my way through, particularly given that I'm also involved 
in moving to Albany at the mo.  I'll be off the air spasmodically, but 
will eventually get back with results - if any.

Thanx heaps

Kev Downes
kdownes at tpg.com.au  ph 0404 7 0808 2
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