laptop fails to "hear" replies

[Lloyd Kvam]

Thanks for responding.

On Sat, 2008-07-26 at 22:57 -0400, Dave Johnson wrote:
> Lloyd Kvam writes:
> > When my laptop boots, it is configured to use a dhcp server.  For some
> > time now, that processing has failed.  I can run 
> >         tcpdump -n ether host <mac address>
> > and see the packets going out, but not the replies.
> > 
> > At the dhcp server, the same tcpdump command shows the requests and
> > replies.
> > 
> > I can get the laptop network stack to function by manually assigning a
> > valid IP address and then repeatedly pinging other computers on the
> > network.  The arp table is empty, showing incompletes for the mac
> > addresses.  Finally a ping will work and the arp table gets filled in
> > and the networking functions are OK from then on.  I can restart the
> > network service and now dhcp works.  (This behavior occurs at other
> > sites, so it is not a switch or cable problem.)
> > 
> > Since everything eventually works OK, I figure the hardware is good and
> > I've fouled up some configuration item.  I've tried enabling and
> > disabling NetworkManager, but it does not seem to have any impact.
> > Stopping iptables also has no effect.
> > 
> > I'm hoping someone can suggest a debugging approach or possibly stuff I
> > misconfigured to create this problem.
> 
> Sounds like your switch(es) are running STP, LACP, and/or EAPoL.
> Any of these can disable your ethernet port on the switch side
> temporarially after link up.  Those protocols will give up after 30-40
> seconds and enable your port.

That timing is right on.  However, it needs to be a problem triggered by
the laptop.  I hit this problem on the road.  How would the laptop force
the port to be disabled?  Also, wouldn't this block the outgoing
requests?  The DHCP server sees the requests and responds.  Could my
laptop be running one of those protocols for some reason and blocking
its own ability to listen?
> 
(further help is now pointless)

I tried upgrading to Fedora9 and things got worse.  I did have an Ubuntu
DVD that I could run live.  It had no difficulties.  So I've shifted to
Ubuntu.  The switch will involve some learning, and probably a bit of
pain.  My files are backed up, so I should be able to recover reasonably
well.


-- 
Lloyd Kvam
Venix Corp.
1 Court Street, Suite 378
Lebanon, NH 03766-1358

voice:  603-653-8139
fax:    320-210-3409