Date: Thu, 30 Nov 2000 10:36:27 -0600 From: David Kelly <dkelly@HiWAAY.net> To: bob@sfcei.com Cc: freebsd-questions@freebsd.org Subject: Re: ftp transfer rates on my LAN Message-ID: <20001130103627.B22943@HiWAAY.net> In-Reply-To: <B9FB8C769C17D411892D00B0D021653203F6D1@sf_pdc>; from bob@sfcei.com on Thu, Nov 30, 2000 at 09:33:24AM -0500 References: <B9FB8C769C17D411892D00B0D021653203F6D1@sf_pdc>
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On Thu, Nov 30, 2000 at 09:33:24AM -0500, bob@sfcei.com wrote: > Just my .02 here. IIRC, Windows seems to max out around 1472 for the MTU, > otherwise there are lots of collisions on the net. I set the MTU on my FBSD > box to 1472 and no collisions. This may affect your throughput, if only > marginally. Ethernet collisions are not bad. Don't sweat 'em until/if they reach 150% to 200%. A 1500 octet packat takes a while to send. But a"collision" happens in the first 64, takes very little wire time. Many NICs do not report these collisions at all. Don't believe I've seen them on 3com NICs I have used. Rather those NICs report *late* collisions which are bad, very bad, indicating a protocol implementation error, hardware failure, or a network which is too long. Yup, the network can get so big the speed of light is no longer fast enough to meet the ethernet timing specs. An analysis I no longer can find the URL for showed a 200% collision rate on 10 Mbps ethernet resulted in an 8% reduction in network capacity. So don't sweat the collisions. In this thread the user has two machines connected point-to-point with a crossed cable. No way for collisions to occur. There might be some advantage to turning on full duplex, which I've never seen auto-negotiated when connected that way, only when connected to a switch which does something to suggest to the machine that full duplex is available. -- David Kelly N4HHE, dkelly@hiwaay.net (hm) ====================================================================== The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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