Possible fxp(4) problem in -CURRENT

John Baldwin jhb at freebsd.org
Tue Oct 18 13:27:17 PDT 2005


On Tuesday 18 October 2005 03:59 pm, Dan Bilik wrote:
> On Mon, 17 Oct 2005 11:46:55 +0200
>
> Dan Bilik <dan at mail.neosystem.cz> wrote:
> > Situation:
> > Single-purpose machines only serving http requests for static content,
> > ...
> > Problem:
> > After some time of serving requests the ethernet interface in the
> > machine stops communicating on the wire. It does not respond to any
> > packets (ping, http, nfs, ssh) and vmstat(8) shows stopped interrupt
> > ...
>
> Some fresh additional info:
>
> Today one of the problem machines got stuck again. I was able to log on
> through second functional interface and watch it more closely. Sending
> packets from the box worked (its arp requests were appearing on other
> boxes in the subnet) but it could not receive any packet. And another
> thing... It seems that running tcpdump (ie. entering and leaving
> promiscuous mode) on the interface resolved the problem
> and made the machine to appear back on the network. It's running
> with no problem from that moment.
>
> Any ideas what's going on here? Does it make sense to anyone?

Well, when you run tcpdump, you put the chip in promiscuous mode, and that 
results in the driver resetting the adapter, which is probably how it became 
unstuck.  You could have probably done 'ifconfig fxp0 down; ifconfig fxp0 up' 
to achieve the same effect.  No idea why the receiver stopped receiving 
frames.  I'm not really an expert on how NICs work.

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org


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