werme@Alliant.COM (Ric Werme) (02/05/91)
I recently got a BSD driver for Rockwell/CMC's CMC-130 Ethernet board running at 1.1 MB/sec for UDP data and 0.8 MB/sec for TCP. (If I get a chance, I'll work on the latter some.) So far we haven't run into any problems talking to systems that can't handle the minimal delay between packets. However, Van Jacobson's reports of problems with Intel 82586 performance leaves me worried about other systems our customers may hookup. Also, I think it was here that some people described a PC system that needed substantial delays between IP fragments. So, I'd appreciate hearing from anyone with experience with Ethernet chips from National Semi, the 32 bit LANCE (I forget its name), and any other chip set about how fast they can receive data. We might as well discuss any problems people have run into with sending data in case customers call up and grumble about only being able to get 500 KB/sec from their FOOBAR/X000 box to us. BTW, the CMC-130 is a pretty solid beast. I've found 4 or 5 bugs in the firmware, all of which will be fixed in their next PROM spin. The board transfers data at about 27 MB/sec over the VME bus so it leaves plenty of bandwidth for slower devices (like disk controllers...). -- | A pride of lions | Eric J Werme | | A gaggle of geese | uucp: mit-eddie!alliant!werme | | An odd lot of programmers | Phone: 508-486-1214 |
vjs@rhyolite.wpd.sgi.com (Vernon Schryver) (02/05/91)
In article <4467@alliant.Alliant.COM>, werme@Alliant.COM (Ric Werme) writes: > I recently got a BSD driver for Rockwell/CMC's CMC-130 Ethernet board running > at 1.1 MB/sec for UDP data and 0.8 MB/sec for TCP. (If I get a chance, I'll > work on the latter some.) So far we haven't run into any problems talking to > systems that can't handle the minimal delay between packets. However, > Van Jacobson's reports of problems with Intel 82586 performance leaves me > worried about other systems our customers may hookup. Also, I think it was > here that some people described a PC system that needed substantial delays > between IP fragments. > ... Delays between IP packets are commonly not needed for TCP, provided the TCP MTU is reasonable and not causing IP fragmentation, and provided the transmitter is reasonable. The familiar NFS drill with slow PC's is to make the buffer size small enough to prevent UDP/IP fragmentation. There are always many systems at Connectathon that require this. There are many standard, relatively low cost workstations that cause ttcp to report > 1Mbyte/sec over ethernet. A concrete example is an IRIS 4D25 running IRIX 3.3.2. There are doubtless many others. I mention the IRIS only so I can note that we've been shipping >=800KB for a long time, and the only troubles reported by customers concerning slow systems have been fixed by adjusting rsize and wsize as noted above. Please note that 800KB for a third party board is a respectible number. The FXP is a respectible board. The person above and CMC are to be congratulated. Vernon Schryver,