Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!cs.utexas.edu!uunet!fernwood!asylum!romkey From: romkey@asylum.SF.CA.US (John Romkey) Newsgroups: comp.protocols.nfs Subject: Re: IO Errors with Sun PC-NFS Keywords: PC-NFS Message-ID: <5602@asylum.SF.CA.US> Date: 28 Sep 89 06:42:44 GMT References: <309@massey.ac.nz> <2701@com50.C2S.MN.ORG> Reply-To: romkey@asylum.UUCP (John Romkey,The Asylum) Organization: The Asylum; Belmont, CA Lines: 47 In article <2701@com50.C2S.MN.ORG> craig@com2serv.c2s.mn.org (Craig S. Wilson) writes: >I use the 3Com 3C501 cards, >which have no on board intelligence. I have found that even when I am >the only user on the network, I get a number of delays. In fact, it >seems to be worse, when there are fewer users. I figure that my pc >can't keep up with the message rate and throws some messages away. > >Am I close? I can't say that I have investigated this phenomenon too >closely. If I had an ethernet controller with onboard intelligence, >would I have the same problems? Sort of. The problem is necessarily one of intelligent vs. dumb cards, though. The problem is that the 3C501 is probably the worst performing ethernet card on the market. The 3C501 is basically a 3C500 on a smaller card, with fewer components. No architectural changes. The 3C500 was the first ethernet card available for the IBM PC. It had a lot of bugs (not surprising) and a major problem with the way buffering is done - it has only one packet buffer, shared for transmit and receive. Because of this, you can't receive packets in rapid succession (never mind back to back) and you can't receive packets while you're loading the buffer with a packet to transmit. So, performance is pretty bad. My experience with intelligent ethernet cards is the only reason you'd want to run most of them under DOS is to save memory (get the TCP stack out of DOS memory). Often the programming interface is so cumbersome that there's more overhead talking to the card than there is doing the TCP protocol. The best performing smart card I've seen is the CMC ethernet card, and it does outperform the card I recommend below, but it's also more expensive. I must admit to not having done any kind of comprehensive tests among various smart cards, so I can't give you exact numbers. For a while, there was an argument that you could use a smart card with a faster processor in it than your PC and thereby gain in performance. Recently they've been lagging way behind in this area, though, and frankly, I'd much rather run my TCP on my 16MHz 80386 than on an 8MHz 80286 or even slower chip. I'd instead recommend a different dumb card, like the Western Digital WD8003E, which is one of the best performing 8 bit ethernet cards, and also one of the cheapest. -- - john romkey USENET/UUCP: romkey@asylum.sf.ca.us Internet: romkey@ftp.com "Live the life you love, Use a god you trust, and don't take it all too seriously." - Love & Rockets