em(4) on FreeBSD is sometimes annoying

[Chris Rees]

2008/8/4 Jeremy Chadwick <koitsu at freebsd.org>:
> On Mon, Aug 04, 2008 at 11:00:16AM +0100, Chris Rees wrote:
>> Martin <nakal at web.de> wrote:
>>
>> > On Sat, 02 Aug 2008 12:55:53 +0200
>> > Torfinn Ingolfsen <torfinn.ingolfsen at broadpark.no> wrote:
>> >
>> >> Just to be sure: also if the first command you try on the interface is
>> >> 'ifconfig up'?
>> >
>> > Hello Torfinn,
>> >
>> > good point, no. The problem appears when the first thing called on this
>> > interface is dhclient (caused by ifconfig_em0="DHCP"). I could also
>> > provoke this behavior after the interface was once up had an IP and was
>> > working (ping). All I need to do is to disconnect the NIC from the
>> > switch when I type "/etc/rc.d/netif restart".
>> >
>> > I have noticed further strange effects here. The behavior seems to
>> > be even more complex.
>> >
>> > After I typed "/etc/rc.d/netif restart", I waited until I get "giving
>> > up" message. Then I plugged the cable in. After about 30 seconds the
>> > link LED was on. I noticed that at this point I couldn't get an address
>> > using DHCP.
>> >
>> > So I disconnected physically the NIC (no cable) and link LED was
>> > still on! ifconfig showed me "state: active" with no cable plugged in.
>> > After further 30 seconds the LED went off.
>> >
>> > I attached the NIC again to the switch again and after 30 seconds
>> > again I got some other effect. The link LED went on (status: active)
>> > and the data LED was permanently blinking (about 2,5 times a second). I
>> > pulled the cable again and now the link LED is still on and the data
>> > LED still blinking (since about 10 minutes already).
>> >
>> > By the way...
>> > Now I'm typing this E-Mail without an ethernet cable plugged in and the
>> > link status LED is still on and the other data LED is blinking.
>> >
>> > --
>> > Martin
>> >
>> I may have misunderstood the purpose of this, but do you have the bpf
>> compiled into your kernel? If you're having DHCP troubles, this could
>> be a problem.
>
> I have never seen "device bpf" cause any sort of DHCP-related problems
> on FreeBSD.
>
> Can you expand on this, and provide reference material confirming such?
>
> --
> | Jeremy Chadwick                                jdc at parodius.com |
> | Parodius Networking                       http://www.parodius.com/ |
> | UNIX Systems Administrator                  Mountain View, CA, USA |
> | Making life hard for others since 1977.              PGP: 4BD6C0CB |
>
>

Sorry, I was referring to the possible absence of it.

Ref:

http://www.freebsd.org/doc/en/books/handbook/network-dhcp.html , section 27.5.4:

"Make sure that the bpf device is compiled into your kernel. To do
this, add device bpf to your kernel configuration file, and rebuild
the kernel."

Chris

-- 
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