DSL: - Digital Subscriber Line Explained

DSL stands for Digital Subscriber. It can carry both voice and data simultaneously. Telephone companies use it to provide internet and voice services.

To provide the phone call facility, telephone companies install copper wires from their offices to customer sites. Phone calls use a small portion of the total bandwidth offered by these copper wires leaving a lot of unused bandwidth. DSL is a modem technology. It uses this extra unused bandwidth for data services. It creates a dedicated point-to-point network between the telephone company's office and the customer site. It uses this network to provide high-speed internet service.

Types of DSL

There are two types of DSL: ADSL and SDSL. ADSL stands for Asymmetric Digital Subscriber Line. SDSL stands for Symmetric Digital Subscriber Line.

Similarities between ADSL and SDSL

The following are the similarities between ADSL and SDSL.

  • Both use the existing telephone lines.
  • Both provide high-speed Internet service.
  • Both create a dedicated circuit between the customer location and the company's office.
  • Both use modems to separate voice and data.

Differences between ADSL and SDSL

The following are the main differences between ADSL and SDSL.

  • ADSL provides a 4 to 5 times faster download speed than the upload speed. For example, if the upload speed is 2MBPS, the download speed will be 8 to 10MBPS.
  • SDSL provides an equal speed for both downloading and uploading. For example, if the downloading speed is 10MBPS, then the uploading speed will also be 10MBPS.
  • ADSL is cheaper than SDSL.
  • ADSL allows you to use both voice and data services simultaneously.
  • ADSL is suitable when you upload less data and download more data.
  • SDSL is suitable when you need identical speeds for both directions.

Advantages of DSL

The following are the advantages of DSL.

Speed: - DSL provides a high-speed Internet connection.

Cost:- DSL uses the existing cables. Companies do not need to install new cables for DSL connections.

Availability: - Since DSL uses existing telephone lines, it is available in all cities having telephone networks.

Security:- DSL creates a point-to-point connection between the customer's location and the company's office. Unauthorized users cannot access data in the middle.

Reliability:- A DSL connection always remains on. A user does not need to connect it manually each time before using it.

Disadvantages of DSL

The following are the disadvantages of DSL.

Distance: - A DSL connection has distance limitations. It works within a limited distance from the company's office.

Speed:- The speed of DSL decrease as the distance from the central office increases.

Cost:- A fiber-optic connection provides more speed at a lower price than a DSL connection.

Disturbance:- DSL relies on telephone lines. Telephone lines are prone to interference from weather conditions and other electrical equipment such as fans, TVs, microwaves, etc.

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