Roll Your Own
Not Only Can You Do Your Own DSL, Here's How to Become a Broadband Tycoon at the Same Time
By Robert X. Cringely
This is the week I said we'd roll our own DSL. On the surface it looks like a daunting task, but it is actually not that hard at all — if you can get past the many regulatory loopholes. But why would you even want to do such a thing? Well maybe DSL isn't available in your area. Maybe you want a significantly cheaper alternative to a T-1 line. Or just maybe you and the kid down the block want to play networked games at warp speed. Well here is how to do it.
DSL is nothing but a pair of copper wires down which bits are pushed. DSL companies go to great lengths to explain how hard this is, but it really isn't. The trick is grabbing the signal off the phone line before it gets to the local phone switch where a band-pass filter limits the frequencies that pass through to 3300 Hz. Outfits like Covad and the other fast-fading national DSL providers use their CLEC (Competitive Local Exchange Carrier) status and presence at the local telco Central Office (CO) to do just that -- grab the signal before it gets wacked.
But there is another way to keep the signal from being messed with and that's by ordering-up from the phone company what's generally called a "dry copper pair." This is just a pair of wires that connect one location with another as long as both locations are served by the same CO. Most telephone companies have (or had) a tariff for dry copper pairs varying from $15-45 per month, though they'll often lie and say it isn't available. Parts of Verizon still have this tariff, which is usually called a "Series 1100 circuit." Historically these dry pairs were used either for the old "leased lines" that connected serial terminals down at the local airline office or they were used by security companies for alarm circuits. A dry pair is just that -- a pair of wires with no dialtone down which you could send a current to ring a bell on the other end. When you go looking for one, try asking first for an alarm circuit (the cheapest way when available), then an OPX (off-premise extension) line, then a paging circuit, or finally LADS (local area data service). Keep running down the list until the phone company says "yes."
In our set-up, we'll be using the pair to send data. This means you have to put devices at each end of the line. One friend of mine in the East uses gear from Telmax while my friend Brett Glass from Wyoming uses PairGain/ADC "Megabit" modems. "These cost about $300 wholesale and can get up to two megabits-per-second, full duplex," says Brett, who lives for this stuff. "It's SDSL technology, so the link is symmetrical. Pairgain's boxes have built-in 'smart' bridges, so you just plug Ethernet into them and they automatically learn which MAC addresses are on each side. We connect our two houses (the one we live in and my wife's computerized weaving workshop) with these. We also connect a few businesses without radio line of sight to LARIAT that way."
LARIAT is Brett's clever wired/wireless cooperative ISP that you can reach through one of the links you'll find under "I Like It."
So now we have a two megabit circuit but no Internet. It's just like buying a T-1 line (E-1, actually -- the European data standard that runs at 2.048 megabits-per-second) for, say $30. But to turn that into an Internet connection, one end has to be plugged to an Internet backbone. There are many ways to do this. Put one end of the circuit at your business. Put one end at your school. Put one end in the machine room at a local ISP.
Of course the local telephone companies hate this whole idea because they want to sell you that T-1 line for $500-600 per month. That's why they will tell you dry pairs don't exist when they usually do exist. And that's why phone companies are trying to get rid of dry pairs as quickly as they can.
Now let's make life worse for the phone companies by being even more clever. Install an 802.11b access point at your end of the line and use it to offer high-speed Internet access to the neighborhood. This is the part of the column that feels to me like the last couple minutes of the song "Alice's Restaurant." What if everyone got a dry pair, made an Internet connection, then offered wireless service to their neighbors. It's a beautiful thing.
And speaking of offering wireless service to the neighbors, there has been a great advance in that area from Linksys, the hyper-aggressive hub makers. This news comes courtesy of Stuart Winokur, technical support manager here at PBS. Linksys has come out with a firmware upgrade for its WAP 11 Wireless Access point that allows two of them to function as Ethernet-to-Ethernet bridges. The firmware is free on the Linksys Website. The firmware also allows use of Ethernet MAC address access lists to restrict connections to a list that is uploaded into flash ROM. That way it is much harder for people to just cruise down your street with a notebook computer, surfing on your bandwidth and stealing your files.
The street price of these Linksys boxes is now down around $250, which is half the price of the next cheapest bridge, from SMC. And the Linksys units have removable antennas, too, so you can add your own high-gainer. Since there are three 802.11b channels in the U.S. that don't interfere, I'm guessing you could put the bridges on Channel 1, 6 or 11, and use an additional Access point in your house set to one of the other non-interfering channels as a standalone access point for wireless connections in your house and to the neighbors.
But let's say you have even grander ambitions. Not content to be a socialist Internet Service Provider, you want to be a capitalist ISP, too. All this dry pair stuff means that anyone who already has dry pairs -- LOTS of dry pairs -- suddenly has an asset they never knew had value. Quick like a bunny, buy-up that stodgy old burglar alarm company that's been limping along in your town for 50 years. They have a dry pair (often more than one) going to every building. Switch the dry pairs to digital, make the alarm service digital, too, then use the old alarm panel and all that excess bandwidth to offer both wired and wireless Internet access to the whole town. With the lowest circuit cost and more circuits than a regular ISP could ever afford, you'll soon be a broadband tycoon.