Open In App

What is DSLAM?

Last Updated : 04 Jul, 2022
Like Article

Digital Subscriber Line Access Multiplexer or DSLAM is a network device that is used by the Internet Service Provider or ISPs often via locating them in telephone exchanges or distribution points, in order to connect multiple DSL (Digital Subscriber Line) to the internet or high-speed digital communicating channel using the multiplexer (a multiplexer also known as MUX is a network device that combines many signals into one by allowing multiple signals to travel via the same communication link). The main aim of the DSLAM technology is to provide the customer with a high-speed internet connection and this is achieved by directing multiple incoming requests to the DSLAM to a single multiplexer from where the device connects to the Internet through its own high-speed capability, the completion of the task/browsing session is completed by the multiplexer receiving the response from websites browsed by the user. 

Function of DSLAM:



From the figure, it can be observed that DSLAMs are used to link the user computer with the ISP.

The data is transmitted from the modem to the DSLAM via a twisted pair cable. Once the data is aggregated by the DSLAM it is converted into a complex signal via the multiplexing technology. The DSL lines are aggregated over the Asynchronous Transfer Mode (ATM), relay frame, or Internet Protocol network in order for the DSL data streams to be forwarded to ATM routers, which then extract the IP traffic and pass it on to an IP router in an IP network. This in simpler terms can be said to be achieved by a BRAS (Broadband Remote Access Server), a  device that routes traffic to and from broadband remote access devices such as digital subscriber line access multiplexers (DSLAM) on an Internet service provider’s (ISP) network. 

The DSLAM functions at the Layer2 of the OSI Model (Open Systems Interconnection Model), hence, it can only transmit signal from the user to the ISP device and vice-versa. 

DSLAMs are generally used by hotels and lodges to maintain in-house communication. For it to be used in the city/town multiple DSLAM and multiplexers will be required along with dedicating themselves to a particular portion of the city.

Characteristics of DSLAM:

  • Used to accumulate multiple DSL signals in order to facilitate high-speed internet connection.
  • DSLAMs are used to link the user computer with the ISP.
  • DSLAM functions at the Layer2 of the OSI Model (Open Systems Interconnection Model).

DSL (Digital Subscriber Line):

These are single communication lines (mainly copper wire), majorly used by the ISPs (Internet Service Providers) to distribute their network/broadband connection in order to provide better bandwidth than the standard bandwidth. DSLs make use of DSL filters or splitters in order to leverage high-speed data transfer. Voice communication over the telephone depicts the application of DSL in real life. 

Purpose of DSL

The main purpose of the DSL line is to assist the transfer of data over single lines, mainly by providing a high broadband internet connection. The purpose is to be able to manage the speed of data transfer on the internet.


There are two types of DSLs:

  1. Symmetric DSL: When the speed of upload and download of data is the same because the frequencies are split evenly, then such technologies are known as symmetric DSLs or SDSL. It is advised to be preferred by the users and is also majorly used by organizations. Examples include Fiber internet, and synchronous digital hierarchy (SDH).
  2. Asymmetric DSLs: Here the download speed is approximately 15 times more than the upload speed. Examples include the WLAN network, ATM, and TCP/IP model.


Both communication (voice) and internet facilities are available in one place at a very effective price because we don’t have to pay for additional wirings because existing telephone lines are used.


The disadvantage of DSL is that they are dependent on the physical distance and are not effective if the distance grows large and might not even work in areas that are devoid of DSL technologies. Also, the upload speeds are slower because it is assumed that the user downloads more data than he/she uploads.

Difference between DSL and DSLAM:

  1. DSLAM is used to multiplex multiple DSLs using the multiplexer technology.
  2. DSLAMs are derived from the DSL network.
  3. DSL is used by a single user while DSLAM is used to benefit a large audience with the help of multiplexing technology.