networking weirdness

[cellio]

Ever since the power surge (and resulting replacement of Linksys box and one other hub), we have been noticing sporadic weirdness on our network. We use DHCP to hand out IP addresses (doesn't everybody?). The Linksys box is configured (by default, if I recall correctly) to start handing out addresses at 192.168.1.100. The Linksys itself is 192.168.1.1. As best I recall, these are the same settings we used successfully on its predecessor for close to three years.

So now, every now and then, it will hand out the address 192.168.1.2. And that unlucky machine will be able to see the LAN but not the internet. Rebooting usually does not fix it, but creative sequences of reboots of all machines and power-cycling of the modem and Linksys usually do the trick.

We cannot find any common factor when this happens. Sometimes it just does.

Tonight, when I found myself the unwilling owner of 192.168.1.2, I decided to try an experiment: I gave myself a fixed IP address without changing anything at the Linksys end. I guessed that I should use 192.168.1.1 for the gateway and name service, rather than the "real" ones; after all, the Linksys box is supposed to resolve the interface issues between the local machines and the network, right?

This worked perfectly. In fact, in a rare Windows moment, I didn't even have to reboot!

I assume that as the other machines encounter the wayward 192.168.1.2 we'll make this adjustment on them, too, until nobody's using DHCP any more. Then we'll forget about this until some unlucky house guest wants to plug his laptop into the network. :-)

I feel like this is an ugly hack. I have not solved the real problem. But at this point I think I'm going to stop looking for it.

Because there is a strict quota on hardware happiness, I found that the 4-port hub we had lying around is really only a 2-port hub. (One is "uplink", which seems to be magic and does not work with anything I tried to plug into it, and one is just dead.) So I can't get rid of the cables strung across the floor just yet.

Comments

[cellio]

Thanks for the clarification.

The weird thing, to me, is that I would expect that if you get the crossover stuff wrong, then the result would be that machines on that hub can't see stuff on the other end of that crossover connection. So, for example, machines on my 4-port hub wouldn't be able to see the internet (which is connected to the next hub over), but would be able to see each other. But the machines can't see each other if I use that connection for anything.

(I suppose it's possible that the connection is simply bad. It lights up, though -- which the known-bad one does not.)

[geekosaur]

Nope. Hubs are dumb; use a non-crossover cable and you will in fact confuse all the ports, because internally they're all connected. Now if it were a switch, you'd be right --- but most switches are also smart enough to tell you when things are miswired, and some will even automatically sense the need for an MDI port instead of an MDI-X and change over automatically.