[techtalk] Poor performance on home LAN

[Nathan T. Lynch]

Hello.

I've been wrestling with a performance problem on my 10baseT home LAN. 
I'm running a linux firewall between the network and a cable modem, and
everything was wonderful until I bought a new desktop machine.

Regardless of which model of network card I use, file transfer times
between the new machine and the firewall are almost always horrible,
usually between 5 and 30 kB/sec.  It doesn't seem to matter too much
whether the file being retrieved is on the firewall's hard drive or on
some ftp server out there.  I have tried tulip, rtl1839, and 3c509 cards
(the first two are PCI 10/100 autosensing, the last is ISA 10bT only). 
ifconfig output on the desktop usually looks something like this after a
typical transfer:

eth0\
Link encap:Ethernet  HWaddr 00:60:08:30:A4:C8  
inet addr:192.168.1.4  Bcast:192.168.1.255  Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
RX packets:124293 errors:175 dropped:0 overruns:219 frame:175
TX packets:101784 errors:0 dropped:0 overruns:0 carrier:24073
collisions:10289 txqueuelen:100 
Interrupt:10 Base address:0x300

Lots of carrier errors, so I tried different patch cables and even
bought a crossover cable, with which I observed similar behavior (so I'm
pretty sure the hub is not the problem).

I ran ifconfig -a on the firewall (hope this isn't too garbled):

eth0\ # lan interface
Link encap:Ethernet  HWaddr 00:80:C8:FA:B7:D6  
inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
RX packets:815174 errors:0 dropped:0 overruns:0 frame:333129
TX packets:1615052 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100 
Interrupt:3 Base address:0x300 

eth1\ # cable modem dhcp'd interface
Link encap:Ethernet  HWaddr 00:80:C8:FA:30:90  
inet addr:xx.xx.xx.131  Bcast:255.255.255.255  Mask:255.255.255.0
UP BROADCAST RUNNING  MTU:1500  Metric:1
RX packets:814213 errors:19 dropped:3163 overruns:0 frame:171719
TX packets:446801 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100 
Interrupt:10 Base address:0x340

What's with the big numbers in the TX 'frame' fields?  I'm not even sure
what that field signifies, someone care to enlighten me?  (man ifconfig
wasn't much help.)

I'm getting the ominous feeling that this might have something to do
with my mobo... like a faulty PCI bus or something?

Any and all help will be appreciated and, hopefully, reciprocated
(eventually).

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