What is Digital Subscriber Line Internet and How Does it Work?

A variety of options are available for accessing the internet, such as coaxial (TV) cable, expensive fiber-optic cables, satellite internet, and DSL. Digital Subscriber Line is typically the cheapest and most widely available of these options.

What is DSL? 

The digital subscriber line (DSL) is a method of accessing the internet over a copper wire telecommunication line. DSL is a method of broadband access alongside cable internet, one of the most common forms of ISPs providing internet access to their customers.

A DSL connection provides download and upload speeds in the range of 5 to 35Mbps while most analog and digital modems offer upload and download speeds of 1 to 10 Mbps.

• Maintaining high-speed internet transfer is one of its main goals.
• To accomplish such a goal, we must use splitters or DSL filters (as illustrated below). The purpose of the splitter is to divide the frequency so that they are not interrupted. 

Types of DSL 

There are two types of DSL – Asymmetric or Symmetric:

• Asymmetric DSL: For downloading from the internet service provider to the subscriber’s computer, asymmetric DSL connections are faster and give more network bandwidth than for uploading in the other direction.

You can read also: What is Local Area Network, Types, and Benefits of LAN?

Providers can increase bandwidth downstream by reducing the bandwidth available upstream, which reflects the needs of most subscribers.

Various forms of asymmetric DSL are:

• ADSL: Stands for asymmetrical digital subscriber line. The ADSL connection can transmit data and voice simultaneously. It offers a downstream bandwidth of up to 8 Mbps and an upstream bandwidth of 384 Kbps. 

• ADSL 2+: With a download speed of up to 20 Mbps and an upload speed of up to 850 Kbps, it offers incredible performance. 

• ADSL Lite: Also known as G Lite, offers slow downstream speeds of up to 1 Mbps and upstream speeds of 512Kbps. 

• R-ADSL: Stands for rate-adaptive digital subscriber line, the modem can adjust the transmission speed so that it delivers the same transmission rates as ADSL.

• VDSL: Stands for a very high bit-rate digital subscriber line, providing downstream speeds of up to 52 Mbps over copper, this is the fastest DSL service. It can also provide downstream speeds of up to 2.3 Mbps over the same copper line. 

• Symmetric DSL: Businesses tend to use symmetric Digital Subscriber Line services because they require greater bandwidth for transferring data than households.

When symmetric DSL services are offered, the bandwidth is provided for both uploads and downloads.

Various forms of symmetric DSL are: 

• SDSL: Stands for symmetric digital subscriber line, providing 1.54 Mbps of transmission speed upstream and downstream. 

• SHDSL: Stands for symmetrical high-speed digital subscriber line, uses the same technology as SDSL, however, the two standards were approved separately by the European Telecommunication Standards Institute and the International Telecommunication Union. 

• HSDL: Stands for a high bit-rate digital subscriber line, offers data rates of up to 2.048 Mbps, but requires multiple phone lines, which ultimately rendered it obsolete. HDSL was developed at the end of the 1990s, making it one of the oldest forms of symmetric DSL. 

• Other Types of DSL: The DSL/ISDN variant known as IDSL (ISDN digital subscriber line) has a low speed (144 Kbps maximum/SDL) and is rarely used due to its inflexible architecture. 

How does DSL Work? 

You will receive a special modem that only supports Digital Subscriber Line connections, or at least only their specific ones (i.e. there isn’t any compatibility with other Internet Service Providers). The computer is connected to your modem, and the modem is connected to a splitter so you can separate internet data from voice.

In most cases, you will use ADSL lines to transport data back and forth from your house to the ISP hub. This stands for asynchronous digital subscriber line, which means one side of the connection (download) is larger than the other (upload). As a result, downloading is fast while uploading is slow to moderate.

If your connection is farther away from the ISP hub, the quality and speed of your connection will suffer. Service providers will not exceed 18,000 feet (3+ miles).

Thus, if you’re at the far end of the line, you’ll have less service than those that are closest, and if you’re outside the range, you won’t be able to access DSL. 

Equipment You Need for DSL Internet 

High-speed Internet using DSL requires some special equipment, most of which is included in the Digital Subscriber Line package from your telephone service provider. The equipment required for DSL internet include:

• Phone Line: This service is provided by your telephone provider and uses your home’s phone line. Since voice, data, and telecommunications lines can be split, you can have internet access and use your phone simultaneously.

Users without a landline telephone at home can also have a dedicated line installed, otherwise, they can connect to DSL lines through the same phone jacks as their voice lines. 

• Router: DSL service providers usually provide routers for their DSL customers; if not, you can purchase routers from many electronic stores. However, keep in mind that telephone companies rarely repair standalone routers if they break down.

If your phone company provided the router to you, you can ask for the manufacturer’s support number. The phone company should be able to provide that number to you. 

• DSL Modem: To connect your computer to the DSL network, you’ll need a Digital Subscriber Line modem, usually included in your DSL service package. DSL modems may be integrated into your routers or may be standalone devices.

If you have a wireless DSL modem at home, you can plug it directly into your computer, either directly into your modem or into a router. The LED lights on the modem will indicate whether it is working correctly or not.

You can read also: What is Local Area Network, Types, and Benefits of LAN?

When a modem problem is indicated, a flashing connection light, check the connections, turn off the unit, and restart it. Telephone companies generally offer technical support for modems. 

• Line Filter and Splitter: To keep DSL and phone data separate, you’ll need a line splitter, available at electronics retailers. The splitter plugs into the jack, providing two jacks instead of one for both purposes.

Both jacks will have the same line, but one will be filtered, so you will plug in your telephone. The other jack plugs into the connection leading to the modem.

Pros and Cons to DSL Internet 

Pros of DSL Internet are:

• It is widely available because it uses existing telephone lines.
• Compared with other internet services, DSL can sometimes be cheaper.
• The latest versions of DSL are becoming faster, but they are still slower than cable and fixed wireless internet.
• The DSL service runs over standard phone lines and no new wiring is required.
• You don’t need to dial in or wait for services to get started – it’s always available.

Cons of DSL Internet are:

• The phone company provides the service, which means that you’ll also need phone service.
• The speed of DSL for your service depends upon your proximity to the main distribution point. The closer you are to the main distribution point, the faster your service. The further you are from the main distribution point, the slower your service will become.
• Data caps are sometimes implemented by DSL providers.

Dialup vs. DSL vs. Cable 

Dialup:

The internet connection of Dial-up is low. However, dial-up is sufficient for most basic tasks such as sending emails with small- to medium-sized attachments.

A dial-up connection can also be used to access the majority of websites, but for sites with graphics, animations, or other tricks, dial-up will not be able to keep up. Dial-up cannot handle real-time viewing or video.

DSL: 

ADSL (asymmetrical) and SDSL (symmetrical) are both types of broadband connections that are significantly faster than dial-up. You can enjoy DSL speeds of several hundred kbps to around 8 Mbps without tying up your phone line. Having DSL always available means no need to dial an ISP.

Using such high speeds allows for high volume data utilization, loading websites quickly, as well as real-time video viewing and online gaming.

Cable: 

Internet connections by cable are faster than dial-up, but they are also slower than DSL. Internet access is obtained by using a cable modem. Cable TV lines are used to share this connection.

The data is transmitted using the TV channels reserved for upstream and downstream transmissions, respectively. 

Is DSL Right for me? 

Yes, DSL is a good choice for households that don’t need high-speed internet, so paying more for a plan you don’t need could result in greater costs. DSL has the advantage of being available almost everywhere, and it’s more cost-effective than satellite or broadband connections.

Internet subscribers have dedicated circuits, just like traditional phone subscribers, so having several users on the network at once doesn’t affect DSL service negatively. A cable Internet connection may slow down during peak Internet usage periods due to neighboring subscribers sharing the cable.