DSL
Digital Subscriber Line
Digital Subscriber Lines (DSL) use your existing, copper telephone line to provide you with a high-speed Internet or Intranet connection from your home or business. Connection speeds for DSL typically range from 128 kbps to 1.54 Mbps, bringing it in-line with T-1 speeds. DSL achieves higher data transfer rates by utilizing more of the available bandwidth spectrum. Ordinary telephone service only makes use of the 0 ~ 3400 Hz frequency range, which accounts for the 56 Kbps speed limit on standard dial-up analog modems. DSL technology breaks the 3400 Hz frequency boundary by outmoding the digital-to-analog conversion that dial-up analog modems perform and connecting both ends digitally. Hence, larger bandwidth is available, allowing for greater transfer rates.
There are several variants or "flavors" of DSL such as SDSL, IDSL, ADSL, HDSL, and UADSL/G.Lite. At the highest level, there are two main categories of DSL: symmetric and asymmetric. Symmetric versions include SDSL and IDSL. As the word implies, symmetric DSL provides the same speeds for both downstream and upstream directions. This technology is ideal for business applications such as email, file transfer, LAN, and server hosting. Asymmetric versions include ADSL, RADSL (Rate Adaptive DSL), and UADSL/G.Lite. In this technology, the upstream speeds are significantly slower than the downstream speeds. This technology is well suited for residential applications such as Web surfing which, in general, does not require a high upstream speed.
In general, business DSL services offer SDSL technology due to the fact that many businesses require a higher upstream speed for file transfers out of their location (as would be the case if a server is hosted). This higher upstream speed is not offered by ADSL technology. Aside from the purely technical aspects of the differing DSL technologies, there are other factors which must be taken into account when determining the ideal solution for your needs. In order to have your internal server and/or network be recognized by the "outside world" you must have a static IP addressing scheme for your DSL connectivity. This is the type of IP address that comes with a business class SDSL offering. Most residential class ADSL offerings only allow for dynamic IP addressing. An analogy to this is to have a temporary address that could and will change over time.
Another consideration is the service level to expect from both service classes. Business DSL usually comes with some sort of service level agreement (SLA) to guarantee a certain level of performance of the DSL circuit. Residential class services normally do not come with any service level guarantees and they offer only a best-effort class of service. In addition, outages can be more commonplace with a residential offering. With SpeedGate's residential DSL services, however, you can expect the same level of service that we provide our business accounts.
There are three main different types of DSL service:
An ISDN Digital Subscriber Line offers speeds up to 144Kbps* and can operate with your existing ISDN modem. It is a two-way connection that offers the same speeds for both your inbound and outbound transmission of data. It can also operate with an existing ISDN connection to avoid the additional cost of a router.
The same two-way connection is also offered as a Symmetric Digital Subscriber Line (or SDSL) which performs both the inbound and the outbound transmission of data at super high speeds (from 192kbps* to 1.1Mbps). SpeedGate's 1.1Mbps service is almost equal to the speed of a T1 service line without spending hundreds of dollars more per month. And with SDSL the same router is used for all symmetrical speeds, unlike ISDN.
An Asymmetrical Digital Subscriber Line (or ADSL) uses the slower band (384Kbps*) for the outbound transmission of data and the faster band (1.54Mbps) for inbound transmission of data. This is a great option for those who are looking to download massive amounts of information!