Re: troubleshooting

Bill Marcum wrote:
On 2008-07-26, stan <smoore@xxxxxxxx> wrote:

Looking at one. I've looked at the packets and they appear to be
correct. The only difference I notice is that the problem machine is
generating a broadcast request while the laptop is using the known
ip/mac address. So I'm thinking the packets are probably OK.

Are all machines using the same netmask and broadcast address?

Yes, the netmask is 192.168.1.255 and the broadcast is 255.255.255.0.

I have one windows machine and two linux machines here. One linux
working and one not working, so I've been focusing on looking for
differences between the two linux machines.

They are running different versions of Suse distributions and one of
them is running an ndiswrapper around windows drivers and that system
works consistently. The other is running linux drivers (rt2x00 from
serialmonkey). I mention that because my instincts here are to focus on
the nonworking machine, but I'm hitting a wall because it looks like the
nonworking machine is generating proper packets.

I've been troubleshooting a long time and I've seen many people get
focused in on something that turns out to be a distraction when the
problem is finally found. That's the real reason I posted here. My gut
keeps telling me to look at the nonworking machine but I don't really
have any observable facts to justify that feeling. In fact, the
observations I have to work with seem very confusing. While my gut
pushes me one way, that little guy on my shoulder keeps whispering not
to get tunnel vision while looking for the problem.

Looking at two, the signal strength seems fine and one of the machines I
used to monitor the problem machines requests with tcpdump is farther
away. I have been in electronics for over 30 years and I've seen a lot
of strange progagation problems but I'm pretty sure the ap is actually
seeing the requests.

Looking at three, I can't find anything that looks like it could impact
arp requests from the wireless side. I've seen the ap respond to
broadcast requests so even though I couldn't find anywhere to turn that
on or off I don't find that a real strong contender.

My actual request here is for someone to tell me if I'm missing
something, or misunderstanding the big picture here. How about it? Any
ideas on what I could do next?

The ap is a Linksys WRT54G wireless router running the latest firmware
and I have no idea how to get past the web interface into the system to
actually see if the arp requests are being seen. I'm not using dhcp here
I use fixed ip addresses. I can ping the problem computer from the
router.

Even when I manually add the arp on the problem machine, it eventually
clears the table when it doesn't get any response to the unanswered
requests. When I reboot the computer it runs for awhile and then fails.
I can restore operation by restarting the network and manually adding
the ap mac to the arp table.
.

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