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l008com · Jun 8, 2008, 02:13 PM

I've got a G4 tower acting as a router. It's built in ethernet port connects to my switch and the pci ethernet connects to my modem.

So the pci card keeps dropping it's IP address. It gets a self-assigned IP. Clicking the renew DHCP button doesn't do anything. Deleted and re-adding the interface doesn't do anything. The only way to get it to pick up it's IP again is to restart the computer. That's kind of odd.

So I figured the problem is either the ethernet card, my modem, or RCN. Of course I own the modem so when I call up they just say it's the modem. The PCI card is an Apple 10/100. The modem is a pretty new Motorola SurfBoard.

I really can't figure out out to figure out what the problem is. I can't switch to the built in ethernet and test that, because even though I use DHCP, I get a static IP from RCN based on my Mac address.

Anyone have any thoughts on this?

besson3c · Jun 8, 2008, 03:00 PM

Is your switch and router or a hub? Is it possible that you have competing DHCP servers?

l008com · Jun 8, 2008, 03:46 PM

My switch is just a switch. My server does the routing.

besson3c · Jun 8, 2008, 03:59 PM

Well, it sounds like the design of your setup is functional (sorry if I'm insulting your intelligence and you are already fully confident of this). I guess it's just a matter of testing and vetting each piece of hardware that is a part of your infrastructure. Does your PCI Ethernet card hold its IP when directly connected to the modem?

l008com · Jun 8, 2008, 04:14 PM

Originally Posted by besson3c

Well, it sounds like the design of your setup is functional (sorry if I'm insulting your intelligence and you are already fully confident of this). I guess it's just a matter of testing and vetting each piece of hardware that is a part of your infrastructure. Does your PCI Ethernet card hold its IP when directly connected to the modem?

It IS connected directly to the modem.

The more I think about it, the more I'm starting to suspect that it is the PCI ethernet card and not the modem or RCN. A reboot always fixes the problem right away, that probably wouldn't be the case if it was the modem, or if it was RCN's infrastructure crapping out.

ghporter · Jun 8, 2008, 05:43 PM

PCI Ethernet cards are cheap. Get a new one and swap it out, which will confirm your hypothesis (I think) that it's the card not the modem (which I think is a real stretch to suspect).

l008com · Jun 8, 2008, 05:49 PM

Originally Posted by ghporter

PCI Ethernet cards are cheap. Get a new one and swap it out, which will confirm your hypothesis (I think) that it's the card not the modem (which I think is a real stretch to suspect).

Powercycling the modem does not get me my IP back. Restarting the computer does. Still think its the modem? I don't see how it could be.
Also, who makes pci ethernet cards that don't need drivers for OS X?

ghporter · Jun 8, 2008, 08:44 PM

I didn't say it well. I meant that it is highly unlikely that it's the modem. As in "it's a real stretch to suspect the modem." Sorry I wasn't clearer.

Cold Warrior · Jun 8, 2008, 08:49 PM

Originally Posted by l008com

I can't switch to the built in ethernet and test that, because even though I use DHCP, I get a static IP from RCN based on my Mac address.

Cable modems/ISPs are pretty predictable about letting one change their device (and therefore the MAC address).

Power off your cable modem and let it sit for at least three minutes. Make the switch from PCI to built-in ethernet, then power on your cable modem. Give it a solid five minutes for the modem to power on, recognize a new MAC, and then authorize it for service.

l008com · Jun 11, 2008, 05:00 PM

Originally Posted by Cold Warrior

Cable modems/ISPs are pretty predictable about letting one change their device (and therefore the MAC address).

Power off your cable modem and let it sit for at least three minutes. Make the switch from PCI to built-in ethernet, then power on your cable modem. Give it a solid five minutes for the modem to power on, recognize a new MAC, and then authorize it for service.

My static IP is based on MAC address. I'd have to call a special number during banker-style hours, and give them the new one. Then repeat when I want to switch back. And if the department is closed then I have to wait. Plus normal techsupport knows nothing of this. It's a pain. It's been steady the past few days though.

ghporter · Jun 11, 2008, 08:15 PM

Originally Posted by l008com

My static IP is based on MAC address. I'd have to call a special number during banker-style hours, and give them the new one. Then repeat when I want to switch back. And if the department is closed then I have to wait. Plus normal techsupport knows nothing of this. It's a pain. It's been steady the past few days though.

Not to argue with you, but I've seen more than a few cable systems where this is what they said...but it's not how the modems worked. For the cost of five minutes of your time, you can see how honest your provider is about this—and if they aren't that honest, it could fix your problem.

l008com · Jun 11, 2008, 08:32 PM

Originally Posted by ghporter

Not to argue with you, but I've seen more than a few cable systems where this is what they said...but it's not how the modems worked. For the cost of five minutes of your time, you can see how honest your provider is about this—and if they aren't that honest, it could fix your problem.

I don't think you get what I'm saying. I can get A connection by doing what you said. But RCN's servers won't give me my static IP unless I give them the new MAC address. I've connected other devices before and I never get my static IP unless I connect with the ethernet card they know about.

ghporter · Jun 12, 2008, 07:02 AM

You're saying that their statements about your IP are true. That I get. Most people just take what the ISP says and never even try to see what the reality is. Again, no offense intended, just looking for ways to poke at this problem.