Collisions using 3Com 3c905C-TX ethernet cards.

[Vesa Laakso <vesa.laakso%asd.fi@localhost>]

I'm having strange behaviour with my NetBSD 5.1 network. I have 2 3Com
3c905C-TX 10/100 Ethernet cards installed on my router/nat -box. I have
only one debian linux behind this router/nat. ex1 for external network
which is connected to Cisco EPC3825 cable modem and ex0 for internal
network which is connected to eth0: RTL8168c/8111c (Debian linux box).

besdi$ uname -a
NetBSD besdi.lan 5.1.0_PATCH NetBSD 5.1.0_PATCH (MOBU1) #1: Sat Apr  9
16:11:39 EEST 2011  
root%besdi.lan@localhost:/usr/src/sys/arch/i386/compile/MOBU1
i386

besdi$ vmstat -i
interrupt                                     total     rate
ioapic0 pin 9                              56817206       53
ioapic0 pin 1                                     4        0
ioapic0 pin 14                              2042073        1
ioapic0 pin 15                                    5        0
ioapic0 pin 22                                   20        0
ioapic0 pin 17                             38025225       36
ioapic0 pin 18                             55527719       52
Total                                     152412252      144

besdi$ netstat -i 
Name  Mtu   Network       Address              Ipkts Ierrs    Opkts
Oerrs Colls
tlp0* 1500  <Link>        00:30:05:67:b5:3c        0     0        0
0     0
ex0   1500  <Link>        00:01:02:0b:53:5e 20113687     0 19920992
16 245868
ex0   1500  192.168.1/24  192.168.1.1       20113687     0 19920992
16 245868
ex1   1500  <Link>        00:04:76:cd:13:7e 36180334     0 20535717
3 151273
ex1   1500  xx.xx.xx/xx  xx.xx.xx 36180334     0 20535717     3 151273
lo0   33192 <Link>                                50     0       50
0     0
lo0   33192 127/8         localhost               50     0       50
0     0
pflog 33192 <Link>                                 0     0     9577
0     0

There is awful lot of Collision. I don't have a switch on my network, I
am using ethernet crossover cable between my Linux and NetBSD router.

dmesg is showing some errors as well:

besdi$ dmesg | grep 'ex'
npx0: reported by CPUID; using exception 16
ex0 at pci0 dev 10 function 0: 3Com 3c905C-TX 10/100 Ethernet with mngmt
(rev. 0x74)
ex0: interrupting at ioapic0 pin 17
ex0: MAC address 00:01:02:0b:53:5e
ukphy1 at ex0 phy 24: Generic IEEE 802.3u media interface
ex1 at pci0 dev 12 function 0: 3Com 3c905C-TX 10/100 Ethernet with mngmt
(rev. 0x74)
ex1: interrupting at ioapic0 pin 18
ex1: MAC address 00:04:76:cd:13:7e
ukphy2 at ex1 phy 24: Generic IEEE 802.3u media interface
ex1:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex1:  transmit underrun (9000) @20
ex1:  transmit underrun (9000) @20, new threshold is 40
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20
ex0:  transmit underrun (9000) @20, new threshold is 40

ifconfig:
ex0: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu
1500

capabilities=3f00<IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx,TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx>
        enabled=0
        address: xx:xx:xx:xx:xx:xx
        media: Ethernet 100baseTX
        status: active
        inet 192.168.1.1 netmask 0xffffff00 broadcast 192.168.1.255
ex1: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu
1500

capabilities=3f00<IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx,TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx>
        enabled=0
        address: xx:xx:xx:xx:xx:xx
        media: Ethernet 100baseTX
        status: active
        inet xx.xx.xx.xx netmask 0xfffff800 broadcast xx.xx.xx.xx

besdi$ iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 32.0 KByte (default)
------------------------------------------------------------
[  4] local 192.168.1.1 port 5001 connected with 192.168.1.10 port 37432
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0-10.0 sec  90.2 MBytes  75.6 Mbits/sec


Any ideas?

Cheers, 

Vesa Laakso