cable modem mac address

Mar 23, 2006 12 Replies

Hello I apologize in advance as I am sure this question has been asked a thousand times but I could not find the exact answer I was looking for googling. I helped someone setup a router on a cable modem today and had to clone the mac address to get it to work. Cable provider is Comcast. Modem Surfboard SB4100. Is there a way to force the modem to reset to a new mac address?


Your syntax is a bit off. I don't think you're asking to change the cable modem's MAC address, but rather you're trying to get a new device (the router) to work behind an cable modem that isn't being changed.

Power-down the cable modem, the router, and the computer. Wait a half a minute or so, and then power things up in order: Modem first (let it sync), then router, and finally the computer.

The router does this during its setup process. At least mine does. When I set up my DLink router and Surfboard 4100 modem, in one of the router's setup screens there is a button to click to "clone MAC address".

Ken

cdoc wrote:

That doesn't mean you need to click it.

Warren Wrote: > Power-down the cable modem, the router, and the computer. Wait a half a

Then, DLR wrote: "I'd go for 10 minutes"

Nope. 3-5 seconds is just fine when reseting a modem. If you're having to wait 10 minutes for a simple power cycle to be sucessful, something else is going on.

Around here TWC learns the Mac address at the other end and you have to be off long enough for the head end to notice and forget the Mac. Don't know what the polling time is but 10 minutes always works. 10 seconds rarely does.

If the MAC hasn't changed and you're just resetting the modem to pick up the downstream devices (router in this case), why would it have to learn the MAC address ?

I'm not sure what the orig. problem was since it's gone from my history.

The issue was if you change the attached "device" how long to make the cable modem forget the MAC address of the attached device. I've found that with TWC in central NC (this may vary greatly elsewhere), you have to turn the modem off for 5 minutes or more to ENSURE the head end will notice it's off and the head end forget the ONE MAC address that it will respond to.

Any of meaning of the start of this and I misunderstood.

I don't see how the head-end is even involved if all you're trying to do is pcik up an modem's attached device's MAC address. I've never had to wait more than seconds.

I sure don't understand that sentence - if it even is one. ;)

Remember that the cablemodem is just a bridge. While it needs to be provisioned for anything behind it to have permission to use the network, it is what's behind the cablemodem that is using the network. Thus the network needs to know what that device's MAC address is. How quickly you'll be able to attach a new device to the cablemodem depends on how quickly the MAC address of that device can be acquired.

That said, it shouldn't take more than a few seconds. If it's taking more than a few seconds, something is wrong.

ISTR that both with OptimumOnline (NY Metro area ISP) and with Charter in MI (where I "recycled" the modem I'd used with OOL), the ISP had to take note of the cable modem's MAC address and authorize/configure that specific device. Otherwise, how do they prevent Fred Freeloader down the street from buying a cable modem, hooking it up, and getting free broadband Internet access? Or how do they prevent me from buying a second cable modem, hooking it up, and getting double the bandwidth free?

Perce

You're getting off on another direction. The discussion was about the MAC address of a device behind the cablemodem, not the cablemodem's MAC address. But yes, the cablemodem's MAC address needs to be provisioned on the network in order to get access to the Internet. Most ISP's now use bottom-up provisioning, that is you plug in the cablemodem, the network recognizes that it's not provisioned, and you're sent to an online provisioning system where you need to enter your account number and other identifying information in order to automatically provision the cablemodem.

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