Wednesday, August 22, 2007

Aging copper cable plant drives — and limits – DSL

AT&T is facing a broadband conundrum brought on by the company’s historical reluctance to invest in upgrading its aging copper cable plant.

In El Dorado County, California, for example where your blogger resides, there are few good pair remaining in large stretches of the cable that in some cases is reportedly three to four decades old. Demand for additional lines from existing and newly arrived residents and businesses taxes the cable’s capacity, resulting in two subscribers ending up on the same line as well as noise and static when summer heat expands the cable and when winter rains penetrate it.


In an ironic twist, Ma Bell’s cable capacity crunch is driving the deployment of Digital Subscriber Line (DSL) service to some neighborhoods, particularly where fiber optic trunk lines are nearby.


Last year AT&T deployed DSL to the remote El Dorado County community of Grizzly Flat, about 25 miles east of Placerville. What prompted this unlikely move was the lack of good pair left in copper cable in the community. The capacity shortage was being exacerbated by people ordering second lines in order to not tie up their phone line with dial up modems — their only option to access the Internet — and for fax machines. Since AT&T already had a fiber optic cable running to Grizzly Flat from Placerville to serve a school there, the company decided to reduce the demand for additional lines by placing a remote terminal in the community fed by the fiber and capable of supporting DSL. DSL runs over a subscriber’s existing phone line and doesn’t require a second line.


That solved one problem but led to another. DSL signals are notoriously weak and prone to attenuation over distance. They require “clean” copper cable in good condition in order to carry the DSL signal reliably. Aged, deteriorating cable on the other hand is a suboptimal carrier, which is exactly what AT&T faces in Grizzly Flat and elsewhere in El Dorado County. Consequently, some Grizzly Flat residents complained, they couldn’t get DSL service because DSL propagated over a shorter than normal distance and their homes were too far away to get service. Poor quality cable also limits customers to AT&T’s lower speed DSL packages since the cable cannot reliably support higher speeds.


A scenario similar to Grizzly Flat appears to be playing out in my neighborhood. DSL wasn’t even on the radar screen here until an infill lot was recently developed. The new resident needs a broadband connection for his home office and ordered up a dedicated T-1 business class data line. That turned out to be the proverbial straw that broke the back of the antiquated cable plant that has been barely able to support plain old telephone service (known in the industry as POTS).


Consequently, AT&T recently installed a remote terminal and may begin offering DSL in the near future pending further testing. As in Grizzly Flat, fiber is available and provides the “backhaul” connection upstream. However, an AT&T planner I spoke with is downplaying the remote terminal’s DSL capabilities. It’s salvage equipment (the faded graffiti on the side of the cabinet is a clue), is not AT&T’s standard DSL remote terminal equipment and may not provide the typical 14,000 foot range. Moreover, if testing shows the copper cable plant needs to be upgraded in order to reliably carry DSL, the planner warns, that would add to the cost of the deployment and increase the odds the bean counters at AT&T corporate will nix it.

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