slow transmission speed

["Shevin, Avraham \(A.N.\)" <ashevin@ford.com>]

I have a strange problem on my home lan... My linux box is acting as an
IP-Masquerading gateway to my cable-modem connection. I have a couple
100Mbit NICs in my machine, and a 100Mbit NIC in each of the other pcs (a
win95 and win98 box). The problem is that transfers FROM my machine to
either of the others maxes out at 10Kbps. Transfers TO my machine from
either of these achieve speeds that are normal for a 100Mbit network. I have
changed the NIC that was serving the lan, and the problem remains. I have an
auto-switching hub, and it indicates that all 3 cards are at 100Mbit.
Changing all cards to run at 10Mbit makes no difference. Yes, I run vmware,
but disabling its networking portions makes no difference. Protocol used for
transer makes no difference, other than FTP is particularly slow. I have
read every bit of relevant documentation, including what I could find on
deja.com and altavista. 

Setup:

Linux box (Debian potato)
	3Com Corporation 3c905B 100BaseTX [Cyclone] (rev 24)
(eth0, 3c59x)		Connected to my cable modem. Works perfectly
	Lite-On Communications Inc LNE100TX (rev 21)
(eth1, tulip)		Connected to LAN. This one has problems

	Routes
		Kernel IP routing table
		Destination     Gateway         Genmask         Flags Metric
Ref    Use Iface
		192.168.91.0    *               255.255.255.0   U     0
0        0 eth1
		192.168.90.0    *               255.255.255.0   U     0
0        0 vmnet1
		24.131.20.0     *               255.255.252.0   U     0
0        0 eth0
		default         nic-c20-001.mw. 0.0.0.0         UG    0
0        0 eth0

	ifconfig for the ethX devices
		eth0      Link encap:Ethernet  HWaddr 00:10:4B:70:B8:B8
		          inet addr:24.131.21.157  Bcast:24.131.23.255
Mask:255.255.252.0
		          UP BROADCAST NOTRAILERS RUNNING MULTICAST
MTU:1500  Metric:1
		          RX packets:97705 errors:1193 dropped:0 overruns:0
frame:1785
		          TX packets:22063 errors:0 dropped:0 overruns:0
carrier:0
		          collisions:0 txqueuelen:100
		          Interrupt:17 Base address:0xdc00

		eth1      Link encap:Ethernet  HWaddr 00:A0:CC:3F:39:A4
		          inet addr:192.168.91.1  Bcast:192.168.91.255
Mask:255.255.255.0
		          UP BROADCAST RUNNING  MTU:1500  Metric:1
		          RX packets:23242 errors:1 dropped:0 overruns:0
frame:1
		          TX packets:24950 errors:0 dropped:0 overruns:0
carrier:0
		          collisions:2 txqueuelen:100
		          Interrupt:18 Base address:0xd800
	
Win95
	SOHOWare card, uses a tulip-compatible chip

Win98
	3Com Corporation 3c905B 100BaseTX [Cyclone]


Avi Shevin
avi@bad.htt-consult.com