hagen@cernvax.cern.ch (per hagen) (05/14/91)
Some of our users in CERN have PCs with 3C500 cards. I have never managed to have them working well with Packet Drivers (tried version 1, 8 and 9) with Novell (BYU IPX.COM) or FTP Software Inc PC/TCP 2.05 ethdrv. The card seems to work better when used with specific 3C500 driver from FTP Software Inc with DMA disabled. The symptom is that the application runs many slower (say 10) with Novell or FTP. A dir on a network drive may take minute(s). I have not yet had a look with a network analyzer as I expect there to be something fundamental wrong with the setup of the PC ... What am I doing wrong ?
jbvb@FTP.COM ("James B. Van Bokkelen") (05/15/91)
The problem is that the 3C500 is a very old design; it only has one buffer on board, so you're either transmitting, copying a packet out to the board, receiving, or copying the packet into the host. You can't do two at once. This makes the card very sensitive to hosts that try to send several packets in close sequence (you miss the 2nd and subsequent packets), or nets where there is a significant amount of broadcast traffic (a broadcast is likely to tie the card up and make it miss a packet directed to it). We recommend that you turn DMA off when using 3C500-family cards in 80286 or greater processors, so you're doing about as well as you can with our driver. We recommend configuring the TCP window to 1024, and disabling the "stream" feature of Interdrive; these may help some. Presumably Novell tries to avoid getting overrun as well, but this inevitably slows you down. If our direct driver manages to out-perform Clarkson's, it is probably because it has gotten more tweaking over the years. In summary, the only thing you're doing wrong is using low-performance cards. Anything currently on the market will perform a lot better... James B. VanBokkelen 26 Princess St., Wakefield, MA 01880 FTP Software Inc. voice: (617) 246-0900 fax: (617) 246-0901