Rescuing the Ethernet Interface after SCB Timeout

Danial Thom danial_thom at
Tue Jan 17 07:49:06 PST 2006

--- Martin McCormick <martin at>

> 	One of our FreeBSD systems has begun randomly
> shutting down
> its Ethernet interface.  After doing so, the
> box continues to try to
> run but prints the following errors in syslog:
> Jan 16 03:01:23 xx /kernel: fxp0: SCB timeout:
> 0x70 0x0 0x50 0x400
> Jan 16 03:01:24 xx /kernel: fxp0: SCB timeout:
> 0xf0 0x0 0x50 0x400
> Jan 16 03:01:35 xx last message repeated 9
> times
> Jan 16 03:01:40 xx /kernel: fxp0: device
> timeout
> Jan 16 03:01:40 xx /kernel: fxp0: DMA timeout
> Jan 16 03:01:40 xx /kernel: fxp0: DMA timeout
> 	If we reboot, the system may be okay for 4
> months or 2 hours,
> who knows?  I can write a shell script to look
> for any new messages
> like those shown above so determining that the
> failure has occurred is
> not difficult especially since the system is
> still running all be it
> without a network connection.
> 	Will bringing fxp0 down with ifconfig and then
> back up as in
> ifconfig fxp0 down
> sleep 5
> ifconfig fxp0 up
> 	restore it to operation again?
> 	I am asking because the system is unreachable
> when fxp0 is
> down.  If one was logged in to that system, is
> there anything we could
> do to rescue it besides a full reboot?
> 	I want to make it rescue itself if it can
> since these things
> always happen on holidays or weekends or at
> 03:00 in the morning.
> 	This system doesn't die that often, but it is
> often enough to
> take measures to prevent it from needing our
> laying on of hands at odd
> hours.
> 	Thank you.

Such things are usually caused by a bus error;
either the card or the bus may be slightly out of
spec, or some other card may be interfering.
You'll see such things, for example, when you put
a PCI-X card on a 133Mhz bus, and then you change
the bus to 100Mhz and it will never happen again.

You might not be able to recover. If you can
replace the card or try a different bus slot. If
your bus is overloaded (ie multiple cards, too
much trace length or too many loads) then
removing one card may fix it. If you are using a
non-intel card with an intel part on it I'd
suggest trying a different card.


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