Date: Tue, 11 Jul 1995 10:38:44 -0500 (CDT) From: Karl Denninger <karl@Mcs.Net> To: dennis@et.htp.com (dennis) Cc: tom@sdf.com, freebsd-hackers@freebsd.org Subject: Re: Wanted: 100bT EISA ethernet recommendation Message-ID: <199507111538.KAA00381@Jupiter.mcs.net> In-Reply-To: <199507111518.LAA07160@mail.htp.com> from "dennis" at Jul 11, 95 11:18:12 am
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> > Tom's opinion.... > > > >On Tue, 11 Jul 1995, dennis wrote: > > > >> The question is, who would build one? EISA cards are too expensive to build > >> and EISA is too slow for a 100mbs medium. If someone is making them then > >> I'll bet they have a much bigger marketing dept than engineering. > > > > That's wrong. EISA is fast enough for 100mbs ethernet. > > It can't be wrong, because any way you slice it its an opinion. Under light > load anything will work, but under heavy load its nice if your bus > throughput is greater than the bandwidth. If your EISA card is bus mastering > it can take over your machine under heavy load. For a workstation, sure, but > not for a server. And EISA is too expensive for a workstation. > > db EISA has a bus bandwidth of 33 mega*bytes* per second. FDDI and friends (fast ethernet, etc) have a bandwidth of about 12 megaBYTES per second. Remember, the 100 is mega*bits*. Divide by 8 to get BYTES. Therefore, you cannot starve the bus with a single EISA 100mbps card. Not possible. It will work, and under very heavy load, with absolutely no problems at all. Similarly, we run multiple EISA 10MBps (megaBYTES) SCSI adapters on EISA bus systems. Very stable, very fast, and no problems. Now if you try to run more than 33 megabytes worth of bus bandwidth (actually, I wouldn't go over about 25) you'll run into trouble under some loading conditions. But heh, you know the design rules, and if you violate them, its your own fault. -- -- Karl Denninger (karl@MCS.Net)| MCSNet - The Finest Internet Connectivity Modem: [+1 312 248-0900] | (shell, PPP, SLIP, leased) in Chicagoland Voice: [+1 312 248-8649] | 7 Chicagoland POPs, ISDN, 28.8, much more Fax: [+1 312 248-9865] | Email to "info@mcs.net" WWW: http://www.mcs.net ISDN - Get it here TODAY! | Home of Chicago's only FULL AP Clarinet feed!
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