Date: Tue, 01 Jun 1999 13:24:38 -0400 From: Dennis <dennis@etinc.com> To: "Jonathan M. Bresler" <jmb@hub.freebsd.org> Cc: hackers@freebsd.org Subject: Re: xl driver for 3Com Message-ID: <199906011828.OAA24383@etinc.com> In-Reply-To: <19990601180304.A259715024@hub.freebsd.org> References: <199906011650.MAA24039@etinc.com>
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At 11:03 AM 6/1/99 -0700, you wrote: > >> >> If your nic driver chains packets (such that there is no time in between) >> you will see good throughput from the box but your overall network >> performance will suffer. A PCI card with continueous traffic can completely >> hog your lan (particularly at 10Mb/s)...which can cause a lot more >> collisions on your network as other devices will not have access until the >> hog is finished sending. For "Fairness" gaps in between frames are better >> as you approach capacity of your wire. >> >> Dennis > > > the interframce gap will allow other hosts to contend for the >wire. the ethernet capture effect decreases as the number of hosts on >the segment increases. the interpacket gap is 9.6uS (or 96 bit >times). an ethernet card listens to the wire before >transmitting a card that is not able to transmit because the wire is >busy will begin transmitting as soon as the wire goes quiet. the max >length of an ethernet is 46 bit times. so a waiting card will alaways >get first crack at the wire. capture effect is due to stations >colliding in trying to access the wire. those that dont collide, are >immune to the capture effect and get the wire first. and if you have 2 cards waiting? or 3? or 10? Im not sure why, but with certain PCI drivers there are a lot more collisions. Dennis To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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