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Posted by
New Visitor
Member Since: ‎09-05-2004
Posts: 2

Connecting the cable modem to a wireless router

Having decided to replace the Comcast supplied router (Netgear CG814WG) I go and buy a D-Link router (Dl-514) from Best Buy only to discover that the new router requires an Ethernet connection from the Cable modem but the Comcast supplied Scientific Atlanta 2200 doesn't have one. At the moment there is a cable splitter with one output going to the modem and the other going to the router.

Apart from taking the D-Link router back to Best Buy and looking for a router that has a cable input is there anything else I can do?
Posted by
Networking Expert
Member Since: ‎07-28-2003
Posts: 24,238

Re: Connecting the cable modem to a wireless router

Huh? You seem to be laboring under some kind of misunderstanding. Your typical home network looks like this:
coax ---------+
|
+-----+--------> (to the TV/set top box)
|
+---------------+
| cable modem |
+---------------+
|
(ethernet)
|
+---(WAN/Intneret Port)---+
| Router |
+-------(LAN Ports)-------+
| | | |
(<- ethernet ->)
| | | |
| | | +-----> Computer 1
| | +---------> Computer 2
| +-------------> Computer 3
+-----------------> Computer 4
The Netgear gateway device you have from Comcast combines the router and cable modem into one device, so it eliminates the ethernet conenction between router and the cable modem, it is both, after all. The D-Link DI-514 is ONLY a router, it must use an external modem. All cable modems given out by Comcast have at least an ethernet interface, and some even have USB interfaces (don't use this, it's bad news for many reasons). Cetainly all the SA modems have an ethernet port that I am aware off. I think you are confusing the SA set top decoder box for a cable modem, which is a big mistake, it's a completely different thing. SA's cable modems look like this.
Posted by
New Visitor
Member Since: ‎09-05-2004
Posts: 2

Re: Connecting the cable modem to a wireless router

Derry - thanks for the explanation ... I've now ordered a cable modem to go with the wireless router.
Posted by
Most Valued Poster
Member Since: ‎07-18-2003
Posts: 7,832

Re: Connecting the cable modem to a wireless router

> Your typical home network looks like this:

Nice picture! Beats the heck out of my...

wall-->modem-->router-->computers

:smileyhappy:
Posted by
Networking Expert
Member Since: ‎07-28-2003
Posts: 24,238

Re: Connecting the cable modem to a wireless router

yeah, but you had yours done quicker than I did and it's also right.
Posted by
New Visitor
Member Since: ‎09-27-2004
Posts: 2

Re: Connecting the cable modem to a wireless router

OK. I'm feeling like an idiot here. Here's the gear : Standard Issue Comcast Scientific Atlanata Cable Modem, Running Win XP, Bought a Netgear WGT624.v2 so the kiddies can play X Box Live. Now, I HAD it all running just fine, don't recall exactly what I did, but it worked. Now, my wife got a new notebook that can access the same wireless system, and IT TOO was working just fine. Then one day it all stopped.All the connections were the same & still plugged in. I backtracked & took everything out, then re-installed according to directions, and no luck. Is there someway I can use the ethernet plug on the modem INSTEAD of the USB, and if so, how the heck do I congigure it??
Posted by
Most Valued Poster
Member Since: ‎07-10-2003
Posts: 7,447

Re: Connecting the cable modem to a wireless router

> Is there someway I can use the ethernet plug on the modem INSTEAD of the USB

?:smileyplain: What do you have connected to USB? The router has to use the ethernet port on the modem. If you mean how can you use the USB port with router, you can't, and you don't want to.

Have you checked to make sure your connection is working with just a pc connected to the modem? Did you reboot the equipment in the right order? modem first, then router, then pc.

Did you check to see if you had a connection using a wired LAN port on the router with a pc? If you were connecting all wireless, you could just be having signal interference problems. Were you getting a valid IP lease in the router status page? Does a wired pc get an IP from the router in ipconfig /all?
Posted by
Networking Expert
Member Since: ‎07-28-2003
Posts: 24,238

Re: Connecting the cable modem to a wireless router

I'll just echo Æñon:). Your description makes NO sense. With the router you can ONLY use the ethernet port on the cable modem, trying to use both the ethernet port and the USB port at the same time without paying extra to Comcast will NOT work. So you need to get rid of the USB connection and go completely ethernet, it's the only proper way to set things up. Your network should look something like this:
--(coax)---+
|
+-------------+
| cable modem |--(usb)-- Nothing connected EVER!
+-------------+
|
(ethernet)
|
+------(WAN)------+
| Router |
+-----(LAN Ports)-+
| | | | |
| | | | +----- Computer 4
| | | +-------- Computer 3
| | +----------- Computer 2
| +-------------- Computer 1
|
(wireless)
|
+---- Wireless Computer 1
|
+---- Wireless Computer 2
|
+---- Wireless Computer 3
|
+---- ...
Posted by
Most Valued Poster
Member Since: ‎08-15-2003
Posts: 1,059

Re: Connecting the cable modem to a wireless router

if you still have problems buy a netgear modem. it doesn't have to be a netgear but keeping in the same company doesn't hurt anything. you will need to call comcast and provision the new modem. then connect the modem to the router's wan port with a cat5e (straight through) patch cable


what model of s.a. modem do you have?? it looks like the 2100's are the only one's on the approved list. the dpx100-110's are being dropped


Message was edited by: gimpy
Message was edited by: gimpy
Posted by
New Visitor
Member Since: ‎07-08-2005
Posts: 3

Re: Connecting the cable modem to a wireless router

Ok, folks...here's another scenario needing advice:

Suppose I have a standard "wired" Netgear 4-port router connected to my Comcast cable modem, and I want to add to the mix another wireless router so I can bring my laptop home from work without having to connect any wires. In other words, is it practical (or even possible) to connect two routers to the output of one cable modem?

What's the best configuration, and what else do I need to change out, upgrade, or rearrange? Can you offer a diagram similar to those above?
Posted by
Most Valued Poster
Member Since: ‎07-18-2003
Posts: 7,832

Re: Connecting the cable modem to a wireless router

> want to add to the mix another wireless router

Most wireless routers have wired ports as well. Mine has 4. Just replace the wired router with a wireless one that has enough ports to meet your needs.
Posted by
Networking Expert
Member Since: ‎07-28-2003
Posts: 24,238

Re: Connecting the cable modem to a wireless router

You don't want another router, wireless or otherwise. You want a wireless access point (WAP). Best to stick with the same brand as the router, so something along the lines of the Netgear WG602. You let the router do the routing and the WAP handles the wireless clients.
Posted by
New Visitor
Member Since: ‎07-08-2005
Posts: 3

Re: Connecting the cable modem to a wireless router

Ok, so for my clarification:

The WAP occupies one of the ports on my existing wired router to allow connection to the wireless laptop? This seems incredibly simple, and here I was expecting another afternoon at the panel, playing with wires and hardware...

Aurora, CO
Posted by
Networking Expert
Member Since: ‎07-28-2003
Posts: 24,238

Re: Connecting the cable modem to a wireless router

You got it. It's that simple.
Posted by
New Visitor
Member Since: ‎07-08-2005
Posts: 3

Re: Connecting the cable modem to a wireless router

Thanks, Baric...

Much appreciated! I can relax now.
Posted by
Most Valued Poster
Member Since: ‎07-10-2003
Posts: 7,447

Re: Connecting the cable modem to a wireless router

I disagree(slightly). Extending the LAN with a WAP is the right solution. But with the cost of wireless routers these days, adding a router may be more practical. WAPs cost at least as much as routers, frequently significantly more, and they're infrequently on sale.

The new wireless router can be connected to the wired router through a LAN port, DHCP disabled, given an IP to access it and you have a WAP, the wired router still issuing all the IPs. Or it could just replace the wired router, depending on the LAN setup. And you have a backup router, just in case. It's not quite plug and play, but it's still simple to set up.
Posted by
Networking Expert
Member Since: ‎07-28-2003
Posts: 24,238

Re: Connecting the cable modem to a wireless router

If you do this, you also have to change the routing mode of the wireless router. You don't want double NAT going on, it can cause problems, not to mention slow you down. All in all, I go the WAP router in this situation or simply replace the wired router with a wireless router. Chaining two router together is certainly doable, but it doesn't get you anything and it does make more work for you.

In networking, there are 20 different ways to achieve your end goal, and best way for one situation is not the same for the next guy or situation. Pick what makes sense to you from a technical and financial standpoint.
Posted by
Most Valued Poster
Member Since: ‎07-10-2003
Posts: 7,447

Re: Connecting the cable modem to a wireless router

No double NAT. Wired router into the LAN port on the switch side of the wireless. Everything's behind the NAT and WAN side is effectively invisible. It's just why pay more for a WAP when a router is cheaper and can be configured to do the same thing. But substituting a wireless for the wired router may be the easiest. If cost isn't and issue, just buy a WAP and plug it in.

There can be some benefit to chaining NAT in rare cases. You could provide greater protection to a critical subLAN from a wireless LAN hung of the WAN. But if it's that important you probably wouldn't be using SOHO routers to begin with.
Posted by
Networking Expert
Member Since: ‎07-28-2003
Posts: 24,238

Re: Connecting the cable modem to a wireless router

That works as long as you know enough to not connect the WAN interface. Most WAP's are cheaper that routers which is why I recommend the WAP as opposed to a full router (not to mention it's easier to hook up), but I guess is depends on what models you're comparing.

I suppose some might want to protect a subsection on their own LAN, but that's not very common. I'll stick with recommending the simple striaghtforward things unless someone mentions unusual requirements.
Posted by
Most Valued Poster
Member Since: ‎07-10-2003
Posts: 7,447

Re: Connecting the cable modem to a wireless router

> Most WAP's are cheaper that routers

Geez, if that's the case then it's a no brainer. I know that used to be true. But from what I've seen lately, because of the much larger volume of routers sold, they are always cheaper or at least your choice if both are on sale for the same price. Maybe you can get a btter deal online. You could also probably get a used one real cheap since many folks are upgrading to routers. Sort of like DDR vc PC100 memory. If you need the low volume stuff you pay it.
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