I've got an old PC (fast 486/slow pentium, unsure) that's had a new lease of life as our firewall, web server and SAMBA server. Used 3com 3c905C-TX card as the LAN-facing NIC as it's
a fast 100Mb/s card and the hub and other PCs (Windoze boxes) are all 100Mb compatible. Interface to rest of the teaching hospital and then on to the internet is via a bog-standard
NE2k compatible NIC that works fine (although only 10Mb/s of course but that's fine).
The setup basically works but saving files onto the box is crawlingly slow. Rates of 500kb/s or less via SAMBA and even slower (50kb/s) via FTP (so I can be sure that the problem is
low-level networking, not Windoze or SAMBA).
Loading files from the server using any technology is very fast.
Looking at diagnostics the one thing that's obvious is that on "/sbin/ifconfig eth1"...
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1149326 errors:0 dropped:0 overruns:20921 frame:0
TX packets:1239052 errors:0 dropped:0 overruns:0 carrier:1
RX bytes:398014948 (379.5 Mb) TX bytes:778774691 (742.6 Mb)
Interrupt:9 Base address:0xfe80
..the "OVERRUNS" figure on the "RX" section keeps going up, it's about 2% of the total packets received. If each time a packet is lost then the whole sequence of TCP packets has to
start from the beginning again (a RESET packet is sent? not much of a TCP expert!) then that means that potentially a 100-300k file (typical for my users) might get quite difficult to
save - this is what the samba logs reflect with several attempts to save files.
Have tried both Donald Becker's 3c5x9.o and 3c90x.o drivers as provided pre-compiled in my SuSE 7.2 distro exactly the same problem with both. (Also I've tried downloading the driver
from 3Com's site and compiling it - that one worked well for about 20 seconds then disconnected from the network completely!!)
My limited understanding might suggest a problem with either a hardware conflict (?) or the driver or the card. The card was fine in the previous machine it was in (Win2k Pro box),
the hardware is PCI and "bus mastering" which I understand means that the network traffic is saved directly into RAM so IRQs are needed less and even on a reasonably busy machine there
should be no overruns??
Have searched FAQs and net to no avail. Can anyone help?
(real email address is carl then the at sign then bookmanassociates.com, no spam please!!!)