Hello all,

I run a RH8 server/router behind a cable modem fed by Comcast. Eth0 in the machine recieves a DHCP address from the modem. Eth1 is set up to feed DHCP addresses to my home LAN.

Last year, when I moved into my new house, I bought a new cable modem. Previously, I had used a Toshiba PCX1100 cable modem which I had for several years. Everything worked fine.

However, when I moved into the new house, and hooked up the new cable modem, it did not work. My server was NOT getting an IP address from Comcast. Over a several day period, I tried 3, count 'em 3 different cable modems and none of them worked. Eventually, I got back the old PCX1100 and as if nothing ever happened, it all worked again!

My problem now is that last night, the PCX1100 finally bit the dust. I am at work ATM, and am dreading the fact that I might not have a working network after buying a new modem tonight...

It seems highly impossible to me that my server will only work with one cable modem on the planet... I mean, really...

Is there something, anything you guys can think of regarding why this is and what I can do to fix it? Is there a config file somewhere that might be, I guess the best word is "entrenched" with the information of the PCX1100 (like a MAC address or something) that means it will only work with that modem unless edited?

There has to be a way to fix this... I would greatly appreciate any thoughts throughout the day because I suspect that as soon as I get home, I'll be cut off.

Thanks a million!

Chris

Check with Comcast to make sure the modem is compatible and I would suspect that you also need to register it with them too. I am not familar with Comcast but that is how it works with Cox.

The old modem, of course, was compatible. The newer ones should have been to. I did call Comcast at that time and asked them if I had to register the new MAC address with them. They told me that they didn't bother with that anymore, and that it was all automatic.

At that time, I did hook up all the other 3 test modems to a PC directly, and they all worked. The server just wasn't picking up an address from them, but all other PC's were.

That's what makes me think there's something in a config file SOMEWHERE on the server that is looking exclusively for the old PCX1100...

I could be wrong, but it's my only working theory.

Thanks for the reply. Any other ideas/thoughts?

Chris

You don't specify models of Cable modem, but is it a safe assumption that they are all connected via ethernet? And if so, connected via ethernet crossover cable?

Have you run dhcpcd with the -d flag to cause it to syslog? (See the dhcpcd manpage for details).

It was a mixed bag of cable modems, mostly Linksys. They were all pretty new at the time. Ethernet, yes. Not cossed over.

No, I don't know about that. Could yu give me some details, please, so I can just print this thread before I go home and have it as a reference?

I am assuming your computer uses dhcpcd, it might use dhclient. I'm not sure with RH8. However, for dhcpcd:
Also, are you using the same ethernet cable as the now-defunct modem? (If they are directly connected, it probably requires a crossover cable)

What does 'mii-tool eth0' show?

Ooooooooooh, wait a tic.

I wonder if I forgot the simplest thing of all... Do you think that, after hooking up a new modem, I need to restart the dhcp service? I don't recall ever doing that.

Although I did boot cold with the new modem attached back then, and that obviously did nothing...

Chris

It's worth a try.

I was using the same cable for all tests. If "what" are directly connected? You mean the modem to the server? They are directly connected. But why would the old modem use a patch cable (which it did), and a new one use crossover?

I don't know what this is. Explain, please?

Thanks a million for all your suggestions. They'll be gold, I'm sure, for when I play with this tonight.

Chris

Ooooooooh, I'm ready to kill...

I just talked to Comcast, and regarding the whole "you have to register a modem" thing mentioned earlier, you DO. Last year when I called, the moron there said I didn't, but apparently that's only if you lease a modem from them, which I don't do. Knowing this, and combined with what ya'll have suggested, I will play with it tonight and let you all know how I make out. Hopefully, the next time I post, it will be from home...

Chris

My guess would then be it's the MAC registration deal. For future reference, mii-tool is a wonderful debugging tool for ethernet interfaces (mii stands for media independent interface). On my desktop, mii-tool eth0 shows:
This can also help you narrow down speed issues on a LAN in some cases.

And will mii be on my server already as a native app for RH8, or will I have to DL and install it (and, if so, where do I get it from)?

Chris

It should be. I *believe* it's part of the net-tools package, which include ifconfig, route, and netstat (among others).

Hmmmmm... Well this is annoying... After getting home last night (I had a new cable modem in hand), I realized that my old one was, once again working.

After all that...

Now 12 hours later and still going.

I'm happy about it, but at the same time, irked.

Chris

I'm still confused by this

I know you have to register the modem with Comcast for it to work properly. Did this actualy occur or is your memory "fuzzy" ?