DSL

DSL (Digital Subscriber Line) technology brings high-bandwidth transmission to homes and small businesses over ordinary copper telephone lines. “xDSL” refers to different variations of DSL (e.g. ADSL, HDSL, and RADSL) that provide high-bandwidth transmission of up to 10 Mbps over your local telephone company’s ordinary copper wire lines. Installation of Asymmetric DSL (ADSL), a popular version of xDSL, appeared in 1998 and soon exploded to offer service throughout the United States and elsewhere. In many areas it has replaced ISDN (discussed later in this chapter).

DSL works by placing special line conditioning and transmission equipment on both ends of an ordinary copper line from your location to the local telephone company’s central office. Because this connection uses a much broader range of frequencies to transmit digital data than a standard analog phone line, higher speeds are possible. Your data is then routed from the telephone company’s central office to your web host/ISP over high-speed trunk lines, then out to the Internet.

DSL offers several advantages over an ISDN connection. Even a “lite” ADSL connection offers from 384 Kbps to 1.5 Mbps of Internet bandwidth as opposed to 128 Kbps with ISDN, i.e., DSL is at least six times faster. Full-rate ADSL can move 8 Mbps, thus having the bandwidth of several 1.5 Mbps T-1/E-1s.

Table 2: DSL comes in a number of variations.
If possible find a DSL service that provides the same speed both upstream and downstream.
Many times such a service is marketed as “business DSL.”

The Different DSL Technologies
Technology	Downstream Rate	Upstream Rate
ADSL (Asymmetric DSL)	1.5 to 8 Mbps	640 to1.5 Kbps
ADSL Lite, G.Lite	384 Kbps to1.5 Mbps	128 to 640 Kbps
CDSL	1 Mbps	128 Kbps
EtherLoop (symmetrical)	125 Kbps to 6 Mbps	Same
G.Lite	384 Kbps to 1.5 Mbps	128 to 384 Kbps
HDSL (High bit-rate DSL)	768 Kbps to 2.3 Mbps	Same
HDSL2	1.5 Mbps	Same
Hotwire ReachDSL	512 Kbps 320 Kbps	Same Same
IDSL (ISDN DSL)	144 Kbps	Same
RADSL (Rate-Adaptive DSL)	7 to 8 Mbps	1 to 1.5 Mbps
SDSL (Symmetric DSL)	160 Kbps to 2 Mbps	Same
SHDSL	Many bit rates: 192 Kbps to 2.3 Mbps	Same

DSL is hundreds of dollars per month cheaper than a burstable or fractional T-1/E-1 connection. A DSL connection gives you acceptable bandwidth to your web server at a fraction of the cost. But DSL is not very scalable.

Since most DSL technologies require installation of a signal splitter there is an up-front installation expense of about $100.00. You also will need to install a DSL router that is connected to your web server’s network hub, which will cost around $75.00. Use only a high-speed “business class” DSL service (i.e. a symmetrical DSL technology that offers the same speed upstream and downstream) to host a web server. Your monthly costs for business-class DSL service should be between $75.00 and $300.00.