On Fri, 23 Jul 1999 11:46:23 +0100 (GMT Daylight Time) "Hugh M. Conner"
<hmc_at_cee.hw.ac.uk> wrote:
> We have a coupe of Alpha servers a 2100 and a 2000. Both are running DU 4.0B.
> Both have a DEC Fast Ethernet card and a DEC Tulip combo ethernet card. The
> fast cards are set to 100Mb half duplex. On the 2100 the combo card is not used
> and on the 2000 is it connected to a thin lan, with the Alpha acting as the
> gateway. The fast ethernet cards are connected to swicthes which also feed
> other machines with 100Mb UTP cards. I have been running some tests using rcp
> to copy a 36Mb file around various machines, and the figures I get from the
> Alphas are worrying. Here's some typical numbers
>
> 2 other machines both with 100Mb half duplex network connection - under 30
> seconds
> Other 100Mb half duplex to other 10Mb thin machine - ~ 1 minute
> Other 100Mb half duplex to Alpha 2100 - ~ 1 min 50 seconds
> Other 100Mb half duplex to Alpha 2000 100Mb - over 3 minutes
>
> What's even more confusing is when I use the 2000 as a gateway, or use the thin
> lan side of it only
>
> 100Mb half duplex to thin lan using Alpha as gateway - ~ 1 min 20 seconds
> thin lan machine to Alpha 2000 thin lan - ~ 50 seconds
>
> Can anyone suggest what is going on here. Why do the 100Mb cards on the Alphas
> give such poor performance, and why is one of them twice as fast as the other.
> Also is there is a problem with the cards, why are the figures with the Alpha
> acting as a gateway ok.
>
> Is there something in the kernel that I need to change to improve the
> performance, or what?
>
> Any help greatly appreciated.
>
Thanks to those who replied. The answer was to do with the autonegotiation on
the card. Although the Alphas and the switch they were connected to claimed to
have negotiated 100Mb half duplex, it seems they didn't really. Turning off
autonegotiation and fixing both sides at 100Mb resulted in greatly improved
transfer times.
And it isn't just Alphas which have this problem. We discovered similar
problems with Suns and a PC running Solaris. Our entire network is now behaving
a lot better.
--
Hugh M. Conner
Computing & Electrical Eng.
Heriot-Watt University
hmc_at_cee.hw.ac.uk
"Life is a lemon, and I want my money back"
Received on Fri Aug 13 1999 - 13:24:49 NZST