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cube4all · May 20, 2004, 10:42 PM

hi All,
have an eMac and Powerbook12", and just recently moved to Jersey where there is Comcast Cable Modem Access. I was using before TimeWarner Cable Internet Access and really did not have any problems. For some reasons, the eMac does not get allocated an IP address where as the PB does. I did not have this problem with TimeWarner. On the cable modem, there is also no connectivity. This is really strange. can anyone help? Thanks in advance.

f1000 · May 20, 2004, 10:48 PM

Are you connecting the two computers through a router to your cable modem?

cube4all · May 20, 2004, 10:50 PM

I don't have a router, directly connected to the modem.

f1000 · May 20, 2004, 11:14 PM

How are you connecting both computers to the cable modem, then?

One at a time?

f1000 · May 20, 2004, 11:20 PM

By the way, you can't just hook up your modem and have it work out of the box. Comcast needs to know your modem's MAC address, first.

I forget if they get the MAC number automatically or if you have to phone it in to them, but give them a call and tell them you have a new cable modem you'd like to use with their service.

stevesnj · May 21, 2004, 08:05 AM

Originally posted by cube4all:
hi All,
have an eMac and Powerbook12", and just recently moved to Jersey where there is Comcast Cable Modem Access. I was using before TimeWarner Cable Internet Access and really did not have any problems. For some reasons, the eMac does not get allocated an IP address where as the PB does. I did not have this problem with TimeWarner. On the cable modem, there is also no connectivity. This is really strange. can anyone help? Thanks in advance.

You need to reset the modem before switching computers, Comcast expects only 1 computers MAC address at a time so you need to unplug your modem, wait a minute then plug it back in then turn on your e-mac. Until you get a router you will have to do this everytime you want to use the internet on each computer.

cube4all · May 21, 2004, 10:27 AM

Thanks for all your help. have tried resetting the modem, and waited a second, but my eMac is still not picking up any IP.

Applefreak01 · May 21, 2004, 12:15 PM

Originally posted by cube4all:
Thanks for all your help. have tried resetting the modem, and waited a second, but my eMac is still not picking up any IP.

I'm sure Comcast has to have the MAC (Media Access Control) address for each computer you want to use your cable modem directly with. Every device that has an ethernet port has a unique MAC address.

I would suggest getting a router that way you can connect your two computers to the routers hub or switch (switch is better) and connect your cable modem to the WAN (Wide Area Network aka Internet) port.

You'll probably have to call Comcast and tell them you got a router and give them the MAC address of the router. After that your router will get a IP address from Comcast and you can setup the router to be a DHCP (Dynamic Host Configuration Protocol) server (you probaly won't need to setup DHCP server on the router it's on by default on most routers) and setup your two computers to work via ethernet with DHCP. After you do that your two computers should have a IP address of something like 192.168.0.x. You'll have to get some cat5 ethernet cable for the computers if you don't have an extra laying around the house. Or get a wireless router and two Airport Extreme cards and go wireless if you don't want to run cables all around your house.

f1000 · May 21, 2004, 12:51 PM

Originally posted by Applefreak01:
I'm sure Comcast has to have the MAC (Media Access Control) address for each computer you want to use your cable modem directly with.

I believe that Comcast needs the MAC address of the modem, not the computers.

Comcast doesn't need the MAC address of the router or any other device on the LAN.

f1000 · May 21, 2004, 12:54 PM

Originally posted by cube4all:
Thanks for all your help. have tried resetting the modem, and waited a second, but my eMac is still not picking up any IP.

Your modem is not a DHCP server. I believe that you need to manually assign each of your computers an IP address.

Applefreak01 · May 21, 2004, 02:29 PM

Or just get a router so you don't have to change cables all the time. Unless your two computers are right next to each other. That's what I would do, but then again I'm lazy

Sod Off Sadr · May 21, 2004, 06:43 PM

Originally posted by f1000:
Your modem is not a DHCP server. I believe that you need to manually assign each of your computers an IP address.

No. Comcast assigns the IP. You either get a static IP--so your location gets one IP all the time, reserved just for you--or a dynamic IP that changes under certain circumstances. Either way, manually assigning your own IP addresses when comcast hasn't instructed you to do so would mess up your net access and most likely keep you offline.

f1000 · May 21, 2004, 07:04 PM

Originally posted by Sod Off Sadr:
No. Comcast assigns the IP. You either get a static IP--so your location gets one IP all the time, reserved just for you--or a dynamic IP that changes under certain circumstances. Either way, manually assigning your own IP addresses when comcast hasn't instructed you to do so would mess up your net access and most likely keep you offline.

Oops, my bad.

cube4all · May 21, 2004, 09:20 PM

i am confused now in terms of action steps. how can I reset the modem, so it will recognize the eMac. when i plug the Lan cable from the modem in the PB everything works w/o configuring anything. it's all different with the eMac. no IP get's assigned. thanks for all your suggestions!

f1000 · May 21, 2004, 09:57 PM

Do you have the eMac set to use DHCP?

Applefreak01 · May 21, 2004, 10:47 PM

Dude, Comcast has to have the MAC address of each device that you plan on using it with. That's why your eMac won't work. They don't have the MAC address of the eMac only the PowerBook.

I just got off live chat with Comcast. Here is what was said:

van.8525_>_Thank you for contacting Comcast. My name is Evan. How can I assist you?
Evan.8525_>_Did you receive my last message?
Evan.8525_>_I have to discontinue this chat if a reply is not received in 20 seconds.
Me>_I have a friend who has Comcast cable modem high speed internet and he wants to be able to use his two computers without a router is this possible?
Evan.8525_>_He can purchase a second cable modem if he has a second outlet to run the other computer on.
Me>_Does Comcast need the MAC address of each device on it's network?
Evan.8525_>_Yes they do.
Me_>_Ok that's what I told him. Thank you for your help.
Evan.8525_>_No problem.
Evan.8525_>_Have a nice weekend

You have to buy another cable modem and high speed connection or buy another IP address for your eMac. I would suggest again getting a router. They are like $40 and you can use both your PowerBook and eMac at the same time. Just call Comcast up and tell them you got a router and that you want to remove the current MAC address they have on file and give them a the MAC of the router and all will work. No need to put yourself through the struggle and pain of trying to get it to work when the solution is simple.

Applefreak01 · May 21, 2004, 10:59 PM

You can get on your PowerBook and go here if you don't believe me.

http://www.comcastsupport.com/sdcuse...asp?direct=yes

Amost every cable broadband ISP needs the MAC address to help keep track of their customers and make sure you are suppose to be getting the service they are providing so anyone can't simply get a cable modem hook to their cable line and computer and get free internet.

Comcast support routers so it's not like they'll say you can't do that. I know of some cable internet providers that don't like routers (they can't charge as much for a single computer as they can with multiple computers). My friend has such an IP. He called them up and said he got a "new" computer and gave them the MAC address but the "new" computer was really a router and it worked.

f1000 · May 22, 2004, 12:07 AM

Originally posted by Applefreak01:
Dude, Comcast has to have the MAC address of each device that you plan on using it with. That's why your eMac won't work. They don't have the MAC address of the eMac only the PowerBook.

I use Comcast through a router, and the ONLY MAC address that I have ever had to tell them was my cable modem's. My local tech support has told me many times that they don't need to know the MAC addresses of any other device on my LAN (neither the router's nor the computers').

Now I'm confused: Why does Comcast need to know the MAC address of a computer directly connected to a modem but not the MAC address of a router connected to a modem?

f1000 · May 22, 2004, 12:15 AM

Originally posted by cube4all:
Thanks for all your help. have tried resetting the modem, and waited a second, but my eMac is still not picking up any IP.

Double-check to make sure that you haven't done any of the no-no's described in this FAQ:

http://faq.comcast.net/faq/answer.js...ubcategory=Mac

Applefreak01 · May 22, 2004, 12:52 AM

Originally posted by f1000:
I use Comcast through a router, and the ONLY MAC address that I have ever had to tell them was my cable modem's. My local tech support has told me many times that they don't need to know the MAC addresses of any other device on my LAN (neither the router's nor the computers').

Now I'm confused: Why does Comcast need to know the MAC address of a computer directly connected to a modem but not the MAC address of a router connected to a modem?

Maybe it's your local tech support doesn't need the MAC address but Cube4all's local tech support might need it. I know my local tech support for Charter Communications didn't need it at first but then as they got more users in my area they did. You'd think that it's be the same for all Comcast tech support.

aaanorton · May 22, 2004, 11:58 AM

Wow, a lot of activity in this thread...
First off, there is no hard and fast rule concerning MAC address requirement, even from branch to branch within the same cable provider. In other words, some people may need to provide a MAC address to their ISP and some will not.
An ISP would categorically not need the MAC address of the modem that they provided to a user. And as most cable ISPs provide modems here in the states, this is a non-issue. The point of ISPs filtering connectivity based on MAC address is so that they can limit the number of machines connecting through your account (they have no interest whatsoever about WHICH modem you are using to establish this/these connections). If your ISP does filter MAC addresses (which it sounds like is the case for the original poster), you have 2 options. Well, really 3, if you include only using 1 computer online, which is hardly an option... You COULD pay your ISP for another IP address for each computer you want to connect. Most cable ISPs offer this, as it's a GREAT way for them to make 2x the money per customer. You would not need another modem/connection for this. The ISP would simply assign 2 IPs to your acct and 1 MAC address would get 1 of them, the other the other. I DO NOT RECOMMEND THIS APPROACH.
The other option is a router. Wired or wireless, these are cheap and simple to use. A router connects to your modem and is seen by you ISP as 1 device. It then assigns connected computers/devices to it IPs from it's own DHCP IP pool, creating a home LAN. A router also prohibits the ISP from seeing any further into the LAN. This means you can have as many computers connected w/o your ISP having any way of determining this. Most cable ISPs have gotten hip to home LANs these days. Some even offer LAN kits to their customers, which, of course, are just routers with higher price tags. Additionally, most (if not all) routers sold currently offer MAC address cloning as a feature. This means that you can set your router up and have it broadcast a MAC address back to your ISP other than its own. This allows you to assign the MAC address of your connectable Mac to the router and you wouldn't even have to call your ISP. This is good, because while most ISP are cool with home LANs, some may want to levy a charge or something. Don't allow them to. There is no technical way for them to prevent you from doing this on your own. A decent wired or wireless router can be bought for less than 50 bucks now. Scan or search through this forum for PLENTY of info about different routers.

Applefreak01 · May 22, 2004, 12:32 PM

aanorton's right it all depends on your local branch if they need the MAC address of each computer or not. It sounds like to me Comcast main tech support for their cable modem broadband needs the MAC address. The local branch where f1000 lives might not care or want to filter MAC address for some reason. Like I said when I first got cable modem from Charter Communications where I live they didn't need the MAC address of my router. But after a month or two my connection stopped working so I called my local tech support and they said they sent out a letter to all their customers saying they now need the MAC address of the computer(s) or router that the customer wants to use with Charter Pipeline. You'd think that all of the local branches would be required to have or not have the MAC address of each computer or a single router that a customer has, but I guess that's not the case.

Getting a router is your easiest and simplest option.

f1000 · May 22, 2004, 01:57 PM

Originally posted by aaanorton:
An ISP would categorically not need the MAC address of the modem that they provided to a user. And as most cable ISPs provide modems here in the states, this is a non-issue.

Not all customers opt to lease ISP modems: I bought both of mine from RadioShack. That's why Comcast asks its customers to alert it on modem changes.

I've never needed to tell Comcast anything about the devices that I connect to my modem. I agree with Applefreak01, though, that there seems to be a difference in policy between ISP's. Maybe Comcast New Jersey does things differently.

tooki · May 22, 2004, 02:00 PM

While Comcast has, in the past, verified by MAC address of the computers you connected, this is not how it is done now.

When Applefreak01 asked Comcast whether they needed the MAC address of every device on their network, the guy correctly answered yes: because the only devices connected to their network ARE THE CABLE MODEMS! They DO need the cable modem's MAC, and then the cable modem's initialization through DOCSIS tells it to only allow one client, namely the first one to connect. That is why the PB works and the eMac doesn't. Rebooting the cable modem should do it, but frankly it's just easier to spend the $50 on a wireless router (eventually, you'll like having wireless for the PowerBook).

tooki

aaanorton · May 22, 2004, 02:21 PM

Originally posted by f1000:
Not all customers opt to lease ISP modems: I bought both of mine from RadioShack.

Ya, when you use another modem, not provided by the ISP, you'd have to provide them its MAC.
Why are you using two cable modems? Different locations?

f1000 · May 22, 2004, 02:37 PM

Thanks, tooki, for clearing that up for us.

f1000 · May 22, 2004, 02:38 PM

Originally posted by aaanorton:
Why are you using two cable modems? Different locations?

No, the second one replaced the first one. Sorry, I should've been clearer.

aaanorton · May 22, 2004, 03:29 PM

Originally posted by tooki:
While Comcast has, in the past, verified by MAC address of the computers you connected, this is not how it is done now.

When Applefreak01 asked Comcast whether they needed the MAC address of every device on their network, the guy correctly answered yes: because the only devices connected to their network ARE THE CABLE MODEMS! They DO need the cable modem's MAC, and then the cable modem's initialization through DOCSIS tells it to only allow one client, namely the first one to connect.

Well, if you connect a computer to the modem, it will get an IP from Comcast's server, making it a part of their network also. I'm not going to argue about what Comcast's MAC address filtering policy is or is not and whether it is or is not enforced, but the way I read that tech's response is that the ISP would need the MAC of any computer connected to the network. Now this may be total bunk, but that seems to be what the guy was saying.
My original point, though maybe not well expressed, was that an ISP couldn't care less about WHICH modem you use, as long as it technically works (though they probably won't offer tech support for a purchased modem). For them, MAC address filtering is about MACs of the computers connecting to the modem. And this is certainly for revenue concerns.
This all brings up another good reason for a router: It adds a layer of protection between the internet and your computer(s).

Applefreak01 · May 22, 2004, 07:57 PM

Originally posted by tooki:
While Comcast has, in the past, verified by MAC address of the computers you connected, this is not how it is done now.

When Applefreak01 asked Comcast whether they needed the MAC address of every device on their network, the guy correctly answered yes: because the only devices connected to their network ARE THE CABLE MODEMS! They DO need the cable modem's MAC, and then the cable modem's initialization through DOCSIS tells it to only allow one client, namely the first one to connect. That is why the PB works and the eMac doesn't. Rebooting the cable modem should do it, but frankly it's just easier to spend the $50 on a wireless router (eventually, you'll like having wireless for the PowerBook).

tooki

Yeah thanks for clearing that up. I guess I should've been more clear when chatting with the Comcast online tech support.

I still say a router is the easiest way to go too. It adds that extra layer of protection as aaanorton said. And like tooki said you'll like having wireless for your PowerBook.

cube4all · May 24, 2004, 12:24 PM

hi,

this thread has gotten some great feedback. i value everyone's response. to make it a bit more interesting:
i tried plugging in my work's laptop (Non-Mac) directly to the cable modem, after using it with my PB, and the Non-Mac laptop had no problem connecting to the Internet. Yes, all devices are set-up on DHCP.

in any case, i am hooking up airport extreme tomorrow, and should be able to get rid of all these problems.