Date: Wed, 21 Mar 2001 20:47:26 +0100 (MET) From: Helge Oldach <Helge.Oldach@de.origin-it.com> To: conrad@th.physik.uni-bonn.de (Jan Conrad) Cc: gordont@bluemtn.net, bright@wintelcom.net, dillon@earth.backplane.com, rdm@cfcl.com, freebsd-stable@FreeBSD.ORG Subject: Re: NFS performance Message-ID: <200103211947.UAA03351@galaxy.de.cp.philips.com> In-Reply-To: <Pine.BSF.4.33.0103211856270.1867-100000@merlin.th.physik.uni-bonn.de> from Jan Conrad at "Mar 21, 2001 6:57:39 pm"
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Jan Conrad: >On Wed, 21 Mar 2001, Gordon Tetlow wrote: >> On Wed, 21 Mar 2001, Jan Conrad wrote: >> >> > ifconfig fxp0: >> > fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 >> > inet 131.220.161.127 netmask 0xfffffc00 broadcast 131.220.163.255 >> > ether 00:90:27:1c:f3:79 >> > media: 100baseTX status: active >> > supported media: autoselect 100baseTX <full-duplex> 100baseTX >> > 10baseT/UTP <full-duplex> 10baseT/UTP >> > >> > server: >> > fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 >> > inet 131.220.161.121 netmask 0xfffffc00 broadcast 131.220.163.255 >> > ether 00:02:b3:1f:f8:c5 >> > media: 100baseTX status: active >> > supported media: autoselect 100baseTX <full-duplex> 100baseTX >> > 10baseT/UTP <full-duplex> 10baseT/UTP >> >> As an aside you probably want to force to 100baseTx <full-duplex> if you >> are using a switch. > >I'll try to convince the administrator of that switch (very difficult) There is a chance that you could do it without bothering the admin. The first thing to do is to look at the collisions (netstat -in). If they are huge (say, >5% of packet total), the switch probably is already at full-duplex, but your machine didn't recognize. In that case you could just ifconfig your NIC and see how it goes. If the collision counter doesn't change even under load, you're done. Otherwise you could try to *force* the switch to "100BaseTX <full-duplex>" using the mediaopt option on ifconfig. Make sure to have the link physically disconnected for a second from the switch, so that the switch observes a trigger to re-negotiate. If you are lucky, the switch will understand your NIC's full-duplex offering and align itself properly. In any case you definitely need to verify that the switch went full-duplex, in particular if you can't look at the port setting by means of LEDs or a management station. A simple test would be a flood ping (-f option) to another machine at the same switch (or, better, to the switch's internal management address). If you see significant packet loss, the switch probably didn't grok it. In that case there is no option but to revert to half-duplex. Background: 10/100 auto-negotiation usually works reliably, but duplex negotiation doesn't (and conceptually can't). This is a Bad Thing: While failing 10/100 auto-negotiation will be immediately visible because the NIC just doesn't work at all, failing duplex negotiation won't be immediately obvious. In fact you probably will see all sorts of strange performance issues if one party is at full and the other is at half, but they won't be obviously pointing to the network cable. So be warned. As a side note I've seen good auto-negotiation results with fxp NICs and assorted Catalysts. Helge To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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