Fast Ethernet and Linux Technical Details

I tested five Linux boxes connected via Fast Ethernet hub, equipped with three SMC EtherPro cards, one 3c905 and four Intel EtherExpress Pro 10/100. The cable lengths are 65 meters (from hub to Torus and Net3), 38m to Mira and 1m to Zeus and Star. For testing aims the binary FTP transfer of a 12MB file has been used. I transferred this file several times in order to obtain maximum results. Firstly, some data.

FTP Transfer File to file File to /dev/null
Zeus -> Torus 810 Kbytes/sec 4.2 Mbytes/sec
Torus -> Zeus 6.1 Mbytes/sec 5.7 Mbytes/sec
Zeus -> Net3 3.9 Mbytes/sec 7.8 Mbytes/sec
Net3 -> Zeus 8.6 Mbytes/sec 8.6 Mbytes/sec
Zeus -> Mira 3.6 Mbytes/sec 7.1 Mbytes/sec
Mira -> Zeus 8.6 Mbytes/sec 8.6 Mbytes/sec
Zeus -> Star 3.4 Mbytes/sec 8.5 Mbytes/sec
Star -> Zeus 7.3 Mbytes/sec 8.3 Mbytes/sec

P133 64 MB RAM, Linux 2.0.27 tulip.c:v0.10+0.72+0.01
eth0: smc9332 (DEC 21140 Tulip) at 0x6100
P120 32 MB RAM, Linux 2.0.27 tulip.c:v0.10+0.72
eth0: smc9332 (DEC 21140 Tulip) at 0xe000
2xPPro200 256 MB RAM, Linux 2.0.27 tulip.c:v0.10+0.72+0.01
eth0: smc9332 (DEC 21140 Tulip) at 0xd800
P120 32 MB RAM, Linux 2.1.21 3c59x.c:v0.30-all
eth0: 3Com 3c905 Boomerang 100baseTx at 0x6000
P120 32 MB RAM, Linux 2.1.30 eepro100.c:v0.32
eth1: Intel EtherExpress Pro 10/100 at 0xe000

Some notes and conclusions:
  • No problems with SMC EtherPro cards. Transfer rate up to 8.6 Mbytes/sec seems reasonable for practical work.
  • I've got many troubles with 3COM 3c905 card. One can see extremely poor transfer rate when receiving data. Ifconfig shows RX errors and dropped packets. I tried several different versions of Donald Becker's 3c59x.c and boomerang.c drivers and experienced no difference. As the transfer rate is much more better when receiving data to /dev/null, one can suppose that a conflict with IDE take place. No solution yet.
  • Intel EtherExpress Pro 10/100 is the cheapest one. There are two problems with this card: (1) at one of my boxes with 3 such cards the initialisation after reboot is unstable. Sometimes I need ifconfig down/up some interfaces in order to make it operational. (2) one of my boxes with this card sometimes (rarely) hangs under the heavy RX traffic. It never happened when received to /dev/null (it sounds that it is the same problem as with 3c59x.c driver, i.e. interference between Ethernet and IDE drivers). It never happened also at the boxes with only SCSI drives.
  • Linux with SMC EtherPro seems very stable. During 8 months we had no any hangs or troubles under rather intensive traffic.
  • Our main router Net3 is now capable to handle Fast Ethernet interface, two 10Mb Ethernets (with 3c509 cards) and 115Kbps serial link. I didn't noticed any overloads and delays. Two parallel FTP sessions 10Mb Ethernet -> Net3 -> Fast Ethernet from two different 10Mb Ethernets runs at the full speed (about 900 Kb/sec). The CPU utilization is about 20-25 percents for this extremal situation.
    Comments and questions to Evgeny Rodichev,
    Last updated 21.07.1997.
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