Re: purpose of fddi mailing list
Vernon Schryver <vjs%rhyolite.wpd.sgi.com@sgi.com> Wed, 28 November 1990 23:39 UTC
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Date: Wed, 28 Nov 1990 15:38:10 -0800
From: Vernon Schryver <vjs%rhyolite.wpd.sgi.com@sgi.com>
Message-Id: <9011282338.AA26912@rhyolite.wpd.sgi.com>
To: Ed Arnold <era@ncar.ucar.edu>
Subject: Re: purpose of fddi mailing list
Cc: fddi@merit.edu
Status: O
> From fddi-relay Wed Nov 28 13:03:01 1990 > Subject: purpose of fddi mailing list > > Not knowing the function of the fddi@merit.edu mailing list ... I'm > interested in knowing if it is an appropriate forum for discussing > performance of commercially-available fddi products. Please e-mail > me if performance issues are *not* an appropriate topic for the list. > > Thanks, > era@ncar.ucar.edu Many of the readers of this list care a lot about the performance of certain commercial FDDI products. Generally, we each have a few products we want to be faster and a lot we want to be slower. It would be nice if we could come up with some generally agreed benchmark or benchmarks. Unfortunately, I have no hope for such a happy outcome. Silicon Graphics sales has been hearing the usual baloney via customers and prospects, so are requesting the same baloney from me. The usually baloney is any of: -quoting UDP instead of TCP, and often UDP transmit rates, sometimes Without checksums. Depending on hardware, checksums can make a big difference. Almost no one now runs UDP without checksums for anything but benchmarks. Many systems can queue UDP packets faster than they can transmit them. Standard BSD-style drivers discard output frames when they get behind. If you are not careful, you end up doing what one ethernet board vendor did in a presentation to me, claiming UDP transmission rates higher than the media speed. Of course, UDP is an important protocol, and I personally care how certain products do UDP. The baloney quoting UDP instead of TCP. -running many TCP circuits, sometimes on several machines, and simply adding the numbers. For example, one board vendor presented a number to me that turned out to be the sum of all of the TCP traffic among three machines. This might be a good benchmark, if what you intend to measure is some kind of aggregate system performance, and if the load is more interesting than simply a bunch of simultaneous ttcp's. -making "minor" changes in the most common TCP benchmark ("ttcp from BRL), and not mentioning that fact, let alone describing the nature of the changes. -running with novel tweaks, such as 32kByte IP packets, over the 4KB FDDI MTU, but not mentioning it. For your purposes, there is little hope. We always ask each other for numbers. To get numbers, you have to give some, but this is all very private. Many of us have products released or in beta sites. The beta sites measure things in their own ways, but are usually constrained by non-disclosure agreements from saying anything publically. At another extreme, we can expect any day to see individual users with FDDI cards in PC's announcing that FTP over FDDI does twice as well as ethernet, achieving all of 100KBytes/second. Many of us have bags of tricks intended to make things faster. We'd be happy to add your suggestions to our own bags, but our bosses would not be pleased if we publically disclosed our own tricks. The numbers I've heard from various sources for products from companies other than mine range from <10Mbits/sec to >80Mbits/sec for TCP. For various reasons, I think the former is a soon to be fixed bug, and the latter is a naked lie. Vernon Schryver, vjs@sgi.com
- purpose of fddi mailing list Ed Arnold
- Re: purpose of fddi mailing list Vernon Schryver