My vision of the perfect world is one where switching between web pages is seamless, a world where one can send and receive large files without having time to make a sandwich during the wait.  A world where you can play online games in real-time or have a NetMeeting with grandma and actually recognize her in the video window.

It appears I will soon be getting my way.

Engineers have come up with a variety of clever approaches to connecting homes for high-speed data communications using existing wiring structures that are in place.  The two most widely used of the new high-speed-data technologies are Hybrid Fiber-Coax (HFC) and Digital Subscriber Line (DSL).  Another “coming soon to a home near you” approach is to run an entirely new fiber optic cable to the home.  I have already begun to see parts of the Atlanta area being wired for fiber to the curb by Bell South.  There are of course other technologies that abandon wires altogether such as the Iridium Satellite Telephone System and other wireless methodologies for delivering data, but for the purposes of this discussion I will attempt to focus on the first three.

First, let me state clearly that there does not exist a clear metric for comparing the performance of broadband technologies.  Though I would like to offer up a clear comparison based on performance, the products are able to deliver a wide range of speeds that depend on how they are actually implemented.  Thus, some if not all of this discussion will be like comparing Apples to Red Tennis Balls.

In this corner, the good people who brought you HBO

Most common folks believe that the cable TV network in their town is just one big wire traversing the whole city with a bunch of splitters branching out the signal to the homes.  What they don’t realize is that in reality the cable companies use a hybrid system made up of Fiber Optic lines that run into distribution points that serve only a few hundred customers.  At these distribution points, or nodes the optical signal is converted into an electrical signal for transmission on the cable line.  Since the optical signal is really data for all intents and purposes someone realized along the way that it would be possible to use one of those TV channels for data transmission instead of yet another infomercial channel.  The capacity of this system is enormous with each 6mhz TV channel allowing around 30mbs of data to be transmitted to the home.  With the ability to allocate multiple channels for data transmission the cable network in effect becomes what is known in technical circles as a ‘big pipe’.  For years the cable companies have been taking advantage of their ‘big pipes’ to push data in the form of television signals into our homes.  What they didn’t do very well, or perhaps I should say “didn’t do intentionally” was allow signals to be transmitted from your house back to them.  By placing reverse filters or traps on your cable line they prevented your neighbor from screwing up your television signal every time he turned on the microwave oven that was next to his TV set.  By replacing these filters with special ones that allowed some signals to traverse the reverse path they paved the way for an Internet revolution.  A lower speed channel is used for the reverse path to carry data from the home to the Internet but since most of the data transmitted is in the form of downstream data such as pictures and audio files from web pages this actually works out pretty well for the average net surfer.  The actual data rate of the system will vary since like with all Internet providers you share the bandwidth with other users but a well designed system will allow you get bursts of data at speed equivalent to several megabytes.  Yep, that’s mega with an “M”!

One common misconception advertised by the uninitiated and those who wish to put their marketing spin on things in order to assist lesser technologies in competing with the cable modem is that because the network is “shared” you will get poor performance or worse be at a greater risk from attacks.

I will debunk the shared bandwidth concept first by saying, “all Internet bandwidth is shared”.  Even with dialup accounts you do not get a 56K pipe to the Internet.  What you get is a 56K pipe to your ISP who then aggregates these into dialup pools and the further aggregates these pools into digital lines like T-1’s.  It is not uncommon to see hundreds of 56K connections sharing one 1.544mb T-1.  Or even several dozen T-1 business customers being aggregated into a single T-1 for delivery to the Internet.  Overselling is common for Internet bandwidth because network engineers realize that their customers will rarely use the whole amount of their bandwidth all of the time.  Thus they can oversubscribe this bandwidth at a rate of 10 to 1 or in some cases even more.  The HFC network is no different except that you share the pipe from your house to the Cable system with other folks but remember this is a really big pipe.  Most times there are no more than a few hundred or so folks sharing the 30mb available to each node, which is most often a smaller over-subscription rate than even the best ISPs.   The HFC network also has a great degree of flexibility for redistributing or recombining the load.  If the engineers monitoring the network notice that it is slowing down they have many options available for boosting throughput for their customers.  These include purchasing more bandwidth to the Internet, allocating more cable channels, and recombining the network so that there are fewer subscribers to each node.

The other issue that is pure hogwash is the concept that because you are connected on the same network as others your PC is more vulnerable to attack because your traffic can be observed by others.  The connection from the cable modem to your node is not like an Ethernet connection where all the packets sent by each user are visible to the other users.  While it is true that the users on a node will share the 30mb pipe available to them, they do this in time slices with each cable modem communicating back to the equipment at the cable company and not with other cable modems.  The only risk you have is that your machine is on the Internet with an IP address.  This is no different than any other Internet connection, including dialup.  Once you get an IP address, your computer is visible to the Internet community as a whole and you should take appropriate precautions.  Having a cable modem connection has no greater security risks than any other Internet connectivity.

Watson, come here, I need more bandwidth.

The telephone company has over the years developed several techniques for transmitting data, some better than others.  Most folks are familiar with the ubiquitous T-1. These lines were initially designed to aggregate multiple telephone lines onto a single wire for delivery into businesses, but some enterprising engineer at Bell labs realized that you could also sell the line as data circuit capable of transmitting at a rate of 1.544Mbps.  Alas, the T-1 has always been priced for commercial voice access putting it out of reach of mere mortals on a budget.  A few years ago the Phone Company started delivering data to residential and business customers over a service called integrated services digital network or ISDN.  With ISDN you get two 64K channels that can be bonded together to form a data pipe of 128K.  But since this is only around 3 times faster than today’s fastest modems and in most areas the cost of the service can be up to 5 times higher, ISDN has been received with a less than enthusiastic response.  What the Telephone Company really needed was something fast that the average Joe could afford.  Enter the digital subscriber line or DSL, a technology from the Telephone Company that holds greater promise.  DSL operates over traditional telephone lines but allows for higher data rates by using different electronics. Because it does not use traditional switching equipment DSL is less expensive to for the Phone Company to deploy than T-1s.  Instead, DSL lines are aggregated by the Phone Company into Digital Subscriber Line Access Multiplexers, or DSLAMs for delivery to either the Internet or your local ISP.  It is here that users will begin sharing the bandwidth with their neighbors.  Also it is at the DSLAM that the greatest amount of over-subscription will generally be seen and this is where most of the bottlenecks for customers may occur.  There are several flavors of DSL but the most common is Asymmetrical DSL or ADSL.  The service is called asymmetrical because they upstream and downstream data rates are much like the cable modem, different in speed.  Most ADSL connections are capable of delivering 3 to 4mbs down to the home but the return path is much slower.  Notice I say ‘most connections’.  The biggest challenge for delivery of ADSL is the aging copper cables used by the Telephone Company.  ADSL is severely limited by distance, there must be less than a few thousand feet of cable between you and the phone company in order for you to get the fastest speeds advertised so your mileage may vary though I bet the price won’t.

Is it Fiber or a big pain in the glass?

The Holy Grail of data transmission is Fiber Optics.  Fiber has advantages over either cable TV or phone lines because it abandons the problems of using electrical signals and instead transmits information over light.  Light pulses can be sent down fiber for great distances without worry of signal degradation or noise from outside sources such as alternative radio stations.  These light pulses are converted at either end to electrical signals that can be recognized by computers and therein lies the rub.  Fiber itself is no more expensive to run that cable TV or copper phone lines.  What is expensive is the equipment necessary to convert the electrical signals first to light then back to electrical signals once they arrive at their destination.  It is this enormous expense that has in the past prevented us from all having fiber lines running or homes.  However, the promise of the ability to deliver voice, video and data all on a single piece of glass has both phone and cable TV companies taking notice.  I will state that this is not something coming soon to a home near you, unless you consider soon being 10 to 20 years.  While it is true that there are some trials of fiber to the curb going on in places like Atlanta, these trials are pretty limited.  There are only a few homes in select areas and if your aren’t willing to fork over more than half a million or so for your house you can pretty much forget being in that area.  Still, as equipment prices come down and technology advances, perhaps I will be able to enjoy surfing over fiber in my retirement years.

But I want it now.

The biggest frustration for consumers is that analysts who never actually had to work for a phone or cable company predicted a much faster roll-out of these new services than was actually possible in practice.  The Phone Company had to invest in new equipment and upgrades as did the cable companies and this work takes time.  Currently, if you don’t live in a sizeable metropolitan area you can pretty much forget getting either a Cable Modem or DSL connection and unless you got the big-bucks fiber is just a glassy pipe dream.

OK Bees, which one is better for me?

That as I stated earlier is a much tougher question because the technologies are different.  Each has strengths and weaknesses and hopefully I have outlined these in an as unbiased manner as I could.  Ultimately you need to decide for yourself based on the information, and not the marketing hype which technology best fits your needs.   Check out not only the price but also what you are getting for your money.  Ask questions about connectivity to the backbone and over-subscription rates.  Call their customer service line to see how quickly they answer and how knowledgeable and helpful their people are.

While it is nice to have super-fast speeds it is important to remember that the ‘S’ in ISP stands for ‘Service’.