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What Are the Different Types of DSL Technology?

DSL technology is either asymmetric or symmetric

By Bradley Mitchell Bradley Mitchell Writer Massachusetts Institute of Technology University of Illinois An MIT graduate who brings years of technical experience to articles on SEO, computers, and wireless networking. lifewire's editorial guidelines Updated on July 11, 2021 Tweet Share Email KreangchaiRungfamai / Getty Images Tweet Share Email Home Networking Broadband The Wireless Connection Routers & Firewalls Network Hubs ISP Ethernet Installing & Upgrading Wi-Fi & Wireless DSL (digital subscriber line) high-speed internet service for homes and businesses competes with cable and other types of broadband internet services. DSL delivers a broadband network using a copper phone line. DSL internet service is either asymmetric or symmetric; most DSL service is asymmetric. The service that is best for you depends on whether you do a lot of streaming or require support for simultaneous voice and video communications.

Asymmetric DSL

Asymmetric types of DSL connections are faster and provide more network bandwidth for downloading from the internet service provider to the subscriber's computer than for uploading in the other direction. By reducing the amount of bandwidth available upstream, service providers can offer more bandwidth downstream, which reflects the typical subscriber's needs. Asymmetric DSL technology is best suited for subscribers who require mostly downstream bandwidth. Forms of asymmetric DSL include: ADSL (asymmetrical digital subscriber line) has a downstream rate of up to 8 Mbps and an upstream rate of 384 Kbps. It supports telephone service and data transmission at the same time. ADSL 2+ delivers download speeds of up to 20 Mbps and upload speeds of up to 850 Kbps. ADSL Lite or G.Lite offers slower speeds of up to 1 Mbps downstream and 512 Kbps upstream. R-ADSL (rate-adaptive digital subscriber line) delivers the same transmission rates as ADSL, but the transmission speed can be adjusted by the modem. VDSL (very high bit-rate digital subscriber line) is the fastest DSL service. It offers downstream rates of up to 52 Mbps and upstream rates of up to 2.3 Mbps over a single copper wire.

Symmetric DSL

Symmetric DSL connections provide equal bandwidth for both uploads and downloads. Business-class DSL services tend to be symmetric because companies have greater needs for transferring data than residences do. Symmetric technology works best for simultaneous voice and video communications, which require high speeds in both directions for effective communications. Forms of symmetric DSL include: SDSL (symmetric digital subscriber line) offers equal upstream and downstream transmission speeds of up to 1.54 Mbps.SHDSL (symmetrical high-speed digital subscriber line) is the same technology as SDSL, but the two standards were approved separately. SHDSL was approved by the International Telecommunications Union, and SDSL was approved by the European Telecommunications Standards Institute.HSDL (high bit-rate digital subscriber line) was developed in the early 1990s, making it one of the oldest forms of symmetric DSL. HDSL offered data rates up to 2.048 Mbps but required multiple phone lines, which eventually made it obsolete.

Other Types of DSL

IDSL (ISDN digital subscriber line) is a hybrid DSL/ISDN technology. It was developed with other types of DSL but is rarely used due to its low speeds (144 Kbps maximum data rate). IDSL offers an always-on connection, unlike ISDN. FAQ What advantages does DSL have as compared to cable? While almost always slower, DSL is cheaper and more widely available, even in rural locations. How old is DSL technology, and when was it first used? DSL tech was developed decades ago, and it entered the mainstream for the first time in the 1990s. Was this page helpful? Thanks for letting us know! Get the Latest Tech News Delivered Every Day Subscribe Tell us why! Other Not enough details Hard to understand Submit More from Lifewire How Fast Is DSL Internet Service? Internet Speed Test Sites (Last Updated October 2022) What Is a Leased Line in Networking? DSL: Digital Subscriber Line Internet Service DSL vs. Cable Types of Network Connections The 9 Best Internet Service Providers of 2022 What Is a DSL Modem? Connect All Your Home Phones to Your VoIP Service Your Options for High-Speed Internet The Differences Between Types of Scanners What Is an AirCard for Cellular Networks? What Is Broadband? Broadband Modems in High-Speed Internet Access and Use 5G: Everything You Need to Know What Is a Modem in Computer Networking? Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up By clicking “Accept All Cookies”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts. Cookies Settings Accept All Cookies