A Digital Subscriber Line Access Multiplexer (DSLAM, often pronounced dee-slam) allows telephone lines to make faster connections to the Internet. Basic principle A traditional landline telephone system also known as "plain old telephone service" (POTS, commonly handles both signaling and audio information The Internet is a global system of interconnected Computer networks It is a network device, located near the customer's location, that connects multiple customer Digital Subscriber Lines (DSLs) to a high-speed Internet backbone line using multiplexing techniques. The Internet backbone refers to the main "trunk" connections of the Internet. For multiplexing in electronics and signal processing see Multiplexer.  By locating DSLAMs at locations remote to the telephone company central office (CO), telephone companies are now providing DSL service to consumers who previously did not live close enough for the technology to work. In the field of Telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls A telephone company (or telco) provides Telecommunications services such as Telephony and Data communications Most of the largest telcos whatever
The DSLAM equipment at the telephone company (telco) collects the digital signals from its many modem ports and combines them into one signal via multiplexing. A telephone company (or telco) provides Telecommunications services such as Telephony and Data communications Most of the largest telcos whatever The term digital signal is used to refer to more than one concept For multiplexing in electronics and signal processing see Multiplexer. Depending on the product being used, a DSLAM would aggregate the DSL lines with some combination of Asynchronous Transfer Mode (ATM), frame relay, or Internet Protocol networks (i. In electronic digital data transmission systems the Network protocol Asynchronous Transfer Mode (ATM encodes data traffic into small fixed-sized cells In the context of Computer networking, frame relay consists of an efficient Data transmission technique used to send digital information The Internet Protocol ( IP) is a protocol used for communicating data across a Packet-switched Internetwork using the Internet Protocol e. , IP-DSLAM that uses the PTM-TC stack)(Packet Transfer Mode - Transmission Convergence).
The aggregated signal is then loaded onto the telco's backbone switching equipment, traveling through an access network (AN)—also known as a Network Service Provider (NSP)—at speeds of up to 10 Gbit/s and connecting to the Internet-backbone. A backbone network or network backbone is a part of Computer network infrastructure that interconnects various pieces of network providing a path for the exchange An access network is that part of a communications network which connects subscribers to their immediate Service provider. A network service provider ( NSP) is a business or organization that sells bandwidth or network access by providing direct backbone access to the Internet In telecommunications Bit rate or Data transfer rate is the average number of Bits characters or blocks per unit time passing between equipment in a data transmission
In terms of the OSI 7 Layer Model, the DSLAM acts like a massive network switch since its functionality is purely Layer 2. The Open Systems Interconnection Basic Reference Model (OSI Reference Model or OSI Model) is an abstract description for layered communications and computer Network protocol A The Data Link Layer is Layer 2 of the seven-layer OSI model. It responds to service requests from the Network Layer and issues service requests to the
A DSLAM is not always located in the telephone company's central office, but may also serve customers within a neighborhood Serving Area Interface (SAI), sometimes in association with a digital loop carrier. In the field of Telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls The serving area interface or service area interface ( SAI A digital loop carrier (DLC is a system which uses Digital transmission to extend the range of the Local loop farther than would be possible using only DSLAMs are also used by hotels, lodges, residential neighbourhoods, and other corporations setting up their own private telephone exchange.
Besides being a data switch and multiplexer, a DSLAM is also a collection of modems. Each modem on the aggregation card communicates with a subscriber's DSL modem. ADSL modem or DSL modem is a device used to connect a single Computer or Router to a DSL phone line in order to use an ADSL The modem function is integrated into the DSLAM itself, rather than being separate hardware like a traditional computer modem. Modem (from mo dulator- dem odulator is a device that modulates an analog carrier signal to encode Digital information Like traditional, voice-band modems, the integrated DSL modem has the ability to probe the line and train itself to compensate for forward echoes and other impairments in order to move data at the maximum rate the telephone line allows. Forward echo: In a Transmission line, a reflection propagating in the same direction as the original Wave and consisting of Energy reflected This is also why twisted pair DSL services have a longer range than physically similar unshielded twisted pair (UTP) Ethernet. Twisted pair Cabling is a form of wiring in which two conductors (two halves of a single circuit) are wound together for the purposes of canceling out Ethernet is a family of frame -based Computer networking technologies for Local area networks (LANs
Balanced pair cable has higher attenuation at higher frequencies, hence the longer the wire between DSLAM and subscriber, the slower the maximum possible data rate. In Physics, attenuation (in some context also called extinction) is the gradual loss in intensity of any kind of Flux through a medium The following is a rough guide to the relation between wire distance and maximum data rate. Local conditions may vary, especially beyond 2 km, often necessitating a closer DSLAM to bring acceptable speeds:
A DSLAM may offer the ability to tag VLAN traffic as it passes from the subscribers to upstream routers. A virtual LAN, commonly known as a VLAN, is a group of hosts with a common set of requirements that communicate as if they were attached to the Broadcast domain A router ('rautər in the USA 'rutər in the UK and Ireland, or either pronunciation in Australia and Canada is a Computer whose software and hardware are usually Though not a full stateful firewall, some DSLAMs also offer packet filtering facilities like dropping inter-port traffic and dropping certain protocols. In Computing, a stateful firewall (any firewall that performs stateful packet inspection ( SPI) or stateful inspection) is a firewall A firewall is an integrated collection of security measures designed to prevent unauthorized electronic access to a networked computer system In the field of Telecommunications, a communications protocol is the set of standard rules for data representation signaling authentication and error detection required to
The DSLAM also supports quality of service (QoS) features like contention, differentiated services ("DiffServ") and priority queues. This article is on differentiated services within communication networks A priority queue is an Abstract data type in Computer programming that supports the following three operations InsertWithPriority: add
Customers connect to the DSLAM through ADSL modems or DSL routers, which are connected to the PSTN network via typical unshielded twisted pair telephone lines. ADSL modem or DSL modem is a device used to connect a single Computer or Router to a DSL phone line in order to use an ADSL A router ('rautər in the USA 'rutər in the UK and Ireland, or either pronunciation in Australia and Canada is a Computer whose software and hardware are usually The public switched telephone network ( PSTN) is the network of the world's public circuit-switched Telephone networks in much the same way that the Twisted pair Cabling is a form of wiring in which two conductors (two halves of a single circuit) are wound together for the purposes of canceling out Each DSLAM has multiple aggregation cards, and each such card can have multiple ports to which the customers lines are connected. In Computer hardware, a 'port' serves as an interface between the computer and other computers or peripheral devices Typically a single DSLAM aggregation card has 24 ports, but this number can vary with each manufacturer. The most common DSLAMs are housed in a telco-grade chassis, which are supplied with (nominal) 48 volts DC. A telephone company (or telco) provides Telecommunications services such as Telephony and Data communications Most of the largest telcos whatever The volt (symbol V) is the SI derived unit of electric Potential difference or Electromotive force. Direct current ( DC) is the unidirectional flow of Electric charge. Hence a typical DSLAM setup may contain power converters, DSLAM chassis, aggregation cards, cabling, and upstream links. The most common upstream links in these DSLAMs use gigabit ethernet or multi-gigabit fiber optic links. Gigabit Ethernet (GbE or 1 GigE is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second, as defined by the An optical fiber (or fibre) is a Glass or Plastic fiber that carries Light along its length
IP-DSLAM stands for Internet Protocol Digital Subscriber Line Access Multiplexer. The Internet Protocol ( IP) is a protocol used for communicating data across a Packet-switched Internetwork using the Internet Protocol The Internet Protocol ( IP) is a protocol used for communicating data across a Packet-switched Internetwork using the Internet Protocol User traffic is mostly IP based.
Traditional 20th century DSLAM used Asynchronous Transfer Mode (ATM) technology to connect to upstream ATM routers/switches. In electronic digital data transmission systems the Network protocol Asynchronous Transfer Mode (ATM encodes data traffic into small fixed-sized cells These devices then extract the IP traffic and pass it on to an IP network. IP-DSLAMs extract the IP traffic at the DSLAM itself. Thus it is all IP from there. Advantage of IP-DSLAM over a traditional ATM DSLAM is in terms of lower capital expenditure and operational expenditure and a richer set of features and functionality. Capital expenditures (CAPEX or capex are expenditures creating future benefits An operating expense, operating expenditure, operational expense, operational expenditure or OPEX is an on-going cost for running a product