I have a 4-port Ethernet board on a 2.0 machine.  Here's the dmesg 
output for it (I think this is everything relevant).

ppb1 at pci0 dev 9 function 0: Digital Equipment DECchip 21152 PCI-PCI Bridge (rev. 0x03)
pci2 at ppb1 bus 2
pci2: i/o space, memory space enabled, rd/line, wr/inv ok
fxp0 at pci2 dev 4 function 0: i82559S Ethernet, rev 9
fxp0: interrupting at irq 3
fxp0: Ethernet address 00:20:fc:1e:67:40
inphy0 at fxp0 phy 1: i82555 10/100 media interface, rev. 4
inphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
fxp1 at pci2 dev 5 function 0: i82559S Ethernet, rev 9
fxp1: interrupting at irq 5
fxp1: Ethernet address 00:20:fc:1e:67:41
inphy1 at fxp1 phy 1: i82555 10/100 media interface, rev. 4
inphy1: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
fxp2 at pci2 dev 6 function 0: i82559S Ethernet, rev 9
fxp2: interrupting at irq 10
fxp2: Ethernet address 00:20:fc:1e:67:42
inphy2 at fxp2 phy 1: i82555 10/100 media interface, rev. 4
inphy2: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
fxp3 at pci2 dev 7 function 0: i82559S Ethernet, rev 9
fxp3: interrupting at irq 11
fxp3: Ethernet address 00:20:fc:1e:67:43
inphy3 at fxp3 phy 1: i82555 10/100 media interface, rev. 4
inphy3: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto

However, when I use more than one interface on that card, the interface 
hangs.  For a while, I thought the problem was the switch, since 
power-cycling the switch cleared things up.  Since I switched to using 
a tlp board, though, I haven't had any such problems.  (The switch is 
at the end of a ~20 meter run from another switch.  I've had other 
machines plugged into it, with no problems; I also have a Linksys 
access point connected to it.)

Thinking further, I was getting similar hangs on a second port on that 
card.  That port is connected via a direct 20 meter run to a switch; 
again, power-cycling the switch would clear the problem.  The 
two switches I had to power cycle are different brands, and one is 
close to the machine.



		--Steven M. Bellovin, http://www.cs.columbia.edu/~smb