Avi Greengart is the Research Director for Consumer Devices at Current Analysis (Mobile Phones, Connected Devices, and Digital Home). He also regularly writes for Slashgear, sporadically blogs at Home Theater View and Tweets far too often as @greengartAvi's expertise lies in understanding consumer electronics marketing, consumer behavior, and technology adoption patterns: where new technologies meet the mass market. 



Avi Greengart is an expert on the convergence of technology and entertainment: video, audio, computing, and wireless, how these are coming together, and what's likely to survive long enough to make a difference in your life.

Column #25 (12/31/2007)

Sharing a Cable Modem: Wired & Wireless Home Networking


Haven’t seen too many computer questions here, but maybe you could help me.  I have two home computers, and the cable company is offering cable modem access, which should be a lot faster than using our dial-up modem.  But the cable company said that if I want to connect the modem to two machines, I need two accounts, and have to pay nearly double.  Is there a way to share just one Internet connection with two computers?

AskAvi replies: 

It’s funny that there haven’t been more computing questions – my professional experience includes a lot of PC software and hardware (marketing, not coding or engineering, but still...).  Let’s answer your question:

Your cable company is greedy.

Yes, there is certainly a way to share an Internet connection: by setting up a home network.  This will also provide you with a host of other benefits, including sharing your peripherals (printers, scanners, etc.), sharing files, and head-to-head gaming.  The downside is that networking isn’t always plug-it-in-and-you’re-done simple, and the manufacturer technical support is uniformly terrible.  If you stick with a single brand of equipment and all your computers have the same operating system you can increase your odds of a smooth installation, but make sure you have a backup support plan before starting (your brother-in-law the gearhead, a high school kid, or the number of a local computer consultant).

There are two types of networks: wired and wireless.  Wired networks are faster, more reliable, and relatively inexpensive.  Wireless networks are more complicated and expensive, but they let you connect computers in different rooms or even floors of your house, without wires hanging everywhere, or opening up your walls to string wires through them.

Wired: Cheap and Reliable 

There’s basically one type of wired network today: 10/100 Ethernet. If a wired network suits your needs, you’ll need:

q       A cable modem – like a phone modem, this converts the Internet feed into signals your computer can understand

q       A cable modem router – this takes the Internet signal from the cable modem, filters it with a firewall so that outsiders can’t get in to your files, and distributes the signal to the network.  Often combined with…

q       A hub or switch – this distributes the Ethernet signals to the computers on your network.  To connect up to four computers to your network, the most economical solution is a Linksys cable router+4 port switch for less than $100. 

q       Cable to connect the cable modem to the wireless access point, and to connect each computer to the hub.  Nearly any brand of “category 5e Ethernet cable” will do; it’s relatively inexpensive and can be purchased at all computer and office supply stores.  I find that paying a bit extra for “snagless” cable is justified – it simply means that the connectors on the ends of the cable are covered so that they don’t get stuck on all the other cables when you connect/disconnect them

q       Ethernet connections on each computer you’re connecting.  Most computers already have this connection built in; if yours doesn’t, even name brand 10/100 Ethernet adapters sell for under $25, but there’s no reason not to go generic.  

q       Networking software, which is built into nearly all modern operating systems.  Microsoft Windows XP is particularly friendly in it’s implementation.  A simple wired network may only require plugging everything in and running the networking Wizard.

Wireless: Look Ma - No Wires!

Wireless networking is a bit more complicated.  There are several types to choose from, unfortunately, none of them work as advertised, and some barely work at all. 


HomePNA networks use your existing telephone wires.  There are two types of HomePNA networks, but I’ve yet to encounter anyone who has gotten pleasant results with either type, so my recommendation is simply to avoid them completely.


802.11b networks send signals through the air similar to the way your cordless phone does.  There are actually several different implementations of the 802.11 standard – 802.11b is the most popular (see sidebar: 802.11what?).  Theoretically, 802.11b networks can work up to 900 feet and transfer data at speeds of 11Mbps, which is fast enough for multimedia with just a few computers, but too slow for a larger network.  However, in actual homes, the range can be limited to as little as 10 feet if there are walls and floors in the way, and the speed can get ratcheted down to as little as 1Mbps. 

If a wireless network suits your needs, you’ll need most of the stuff you needed for wired networks, plus a few extra items.  Your shopping list includes:

q       A cable modem

q       A cable modem router

q       An 802.11b wireless access point – this is your wireless data transmitter and conversion center from wireless to wired networks

q       A hub or switch – you’ll only need this if you plan to connect some computers via wires in addition to wireless connections.

q       Cable to connect the cable modem to the wireless access point, and to connect any wired computers to the hub

q       Ethernet connections on each computer you’re connecting via wires

q       802.11b receivers for each computer you are connecting wirelessly to the network.  There are two types of these: PC card receivers, and USB receivers.  The PC cards are perfect for notebook computers, but in order to use them in desktop computer, you’ll also need a PC card adapter.

q       Networking software, built into nearly all modern operating systems.  Again, having the same operating system on each computer simplifies things, and Windows XP simplifies things further.

Theoretically, any 802.11b device will work with any other.  Don't.  With an 802.11b network, it is critical to buy the same brand of transmitter (the access point) and receiver.  I don’t generally recommend specific brands when there are so many choices, but experience suggests that the Linksys 802.11b product line causes the least amount of headaches.  Happily, they also have some of the lowest prices and most convenient products: I'm quite happy with their nifty combination product: a cable modem router + wireless access point + 4 port switch.  It supports up to 4 wired and 255 wireless connections, and was selling recently at Amazon.com for $150.  The manual is not written for novices, and it doesn't provide anywhere near the range or speed advertised on the box.  But as these things go, it is an excellent product.

So, for your modem sharing project you’ll need to invest an additional $120 – 500 up front to set up your network, and you may have to deal with some nasty setup complications.  But after that you should be set – no extra fees to your cable provider.  And you can reap all the other benefits of a home network – streaming audio and video, printer sharing, file sharing, games, and more.



802.11a networking gear has recently appeared, and it operates at a higher frequency than 802.11b – which may increase the range somewhat – and at much higher speeds of up to 54Mbps.  However, the “a” version isn’t compatible with “b” equipment, and it costs hundreds of dollars more.  Other versions of 802.11 have been announced for later this year which promise compatibility with “a” and “b” while maintaining the higher speeds.

Despite its drawbacks, 802.11b is rapidly becoming a universal standard – if you have a notebook computer equipped with an 802.11b networking card, you can wirelessly surf the Internet at home, at a few airports, and soon at many Starbucks.  A better selection of products are available for 802.11b, and they are considerably less expensive.  For home use, I currently recommend using 802.11b, not 802.11a.

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