Thursday, March 08, 2007

Distance Restrictions In Rural Applications....DSL vs T1

Here's a question often asked by those in rural areas needing dedicated bandwidth for their network applications.

"If someone wanted to have a T-1 line (or fractional T-1) installed in a very rural location, are they subject to the same distance restrictions as a DSL line is?"

The general answer is no. T1's do not have maximum distance "limitation" as does DSL. Network carriers can use multiple T1 repeaters to regenerate (not just amplify) the T1 signal.

However, 2 distance "sensitive" components can increase T1 cost.

First, the T1 access loop. Most local exchange carriers (LECs) (e.g., AT&T/SBC/BellSouth, Qwest and Verizon) charge the ISP for T1 access based on distance between the ISP's router (Internet POP) and the customer's local serving exchange (LEC Central Office.) That is why most ISP's T1 quote tools require the customers local phone number, or at least the 1st 6-digits (NPA-NXX) which identify the local CO exchange, in order to caculate the distance to the ISP's closest IP POP (Internet router).

Second, extrordinary construction costs. If the customer location is a great distance from the closest T1-equipped LEC central office, then the LEC must install additional T1 repeaters and possibly incur other transmission equipment / construction costs to reach the customer. In this case, the LEC has 2 options to deal with construction cost: either absorb cost themselves, or pass it on to the ISP who then pass it on to the end-user customer. I've been implementing T1s for awhile and have seen this situation a few times. Twice the one-time construction costs were $10-$20K and the customer canceled the order. Once, BellSouth had to trench ~200 feet to lay new cable and they absorbed this cost.

Assuming no extrordinary construction cost, there are ISPs that offer flat rate Internet T1s for $750 per month, anywhere in US, with no distance limitations between ISP POP and customer's serving CO. The flat rate cost includes T1 access loop and 1.5 Mbps Internet port. In the majority of cases these aren't always the most reliable providers when you consider long term stability, QoS, and SLA though.

However, for most locatons that are under 25 miles to the ISP POP, we are seeing Internet T1 prices in the general range of $300-$500 per month +/-.

The upside is that it's full speed in both directions, and not subject to the EULA restrictions that DSL lines are. Typically, ISP's don't want you running services behind a DSL line, no such problem with the T1.

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