[KLUG Members] MAC/IP conflict

[Peter Buxton]

First off, thanks for talking me down. :) I had two 4am nights in a
row and wasn't feeling, ah, well, human for a while there.

Since the network isn't failing right now, I'm going to install the SCSI
card and DAT and do a backup, as we haven't had one since Wednesday. I'm
also curious to see what a reboot will do to our environment.

On Sat, Nov 09, 2002 at 08:27:56AM -0500, Bruce Smith wrote:

> > Because the source of the conflict is far from clear.
> 
> Are you sure it's a IP conflict?  I thought you confirmed that, and I
> was going on that assumption.

With no logs giving errors, but a couple WinXP Pro boxes giving DHCP/IP#
conflict errors, I thought that one of the two other businesses in this
building might have patched into our hub by accident and two boxes were
duking it out over our server's IP#. However, a thorough trace of all
our wiring has removed that possibility (but left us an updated map!).

We have several laptop users, but only one left her laptop here for the
weekend.

Two possibilities exist: that the IP conflict reported by the WinXP
boxes were caused by the server being unavailable to service the DHCP
request, or the server was knocked off by a misconfigured box ignoring
DHCP and trying to seize a taken IP#. However, after a thorough shutdown
of all the machines on the network, then bringing them up one by one,
I've not seen this problem since. With the single DHCP server getting
knocked off the net for minutes at a time, the chances of DHCP remaining
coherent were not good.

We are also, temporarily at least, free of being knocked off our NIC.
Hmmm.

> I've seen other problems that are similar to what you described, where
> some device on the net starts spewing out garbage for no good reason,
> and causes a lot of problems.

> Do you have hubs or switches there?  Are they intelligent?

That's what I'm wondering. However, I've seen this behavior on our old
hub and our new switch. The switch does route by MAC address, but is
otherwise not intelligent; nor does it sport a CLI. It still could be a
bad device, and probably is. I suspect the HP 5n JetDirect printer:
unplugging it gave us an error-free Friday until about 4:30 pm.

> What changed Monday, (or Friday, or the weekend, ....) ???  May be
> "nothing" if it's a port gone nuts, as I described above.

Nothing on the server.

-- 
for gpg key: http://killdevil.org/~peter
Not playing Elvis Costello isn't as good
as not playing Bob Dylan. -- lsg