BACKBONE DEFINITION TELECOM SERIES

The payload section carries the actual information, which can be data, voice, or video. The header provides addressing information for switching the packet to its destination.

Large corporate networks using an ATM backbone might use a switch-to-switch connection to the carrier’s network instead of CPE.ĪTM uses fixed-size packets called “cells.” Each 53-byte ATM cell contains 48 bytes of data payload and 5 bytes of control and routing information in the header. The kind of CPE needed varies with the access method employed-for example, Channel Service Unit (CSU) for T1 line, frame relay access device (FRAD) or router for frame relay, and so on. Typically a subscriber would lease a T1 or T3 line to connect their customer premises equipment to the telecommunication carrier’s ATM network, but frame relay or SONET can also be used to connect a site to an ATM network. A connection-oriented technologyĪTM is a connection-oriented technology that requires the establishment of a specific network path between two points before data can be transported between them. A virtual path is a collection of VCs having the same source and destination points that can be used to pool traffic being transmitted to a given destination. A VC exists only while data is being transmitted on it, and all cells in a given ATM transmission follow the same VC to ensure reliable data transmission.

BACKBONE DEFINITION TELECOM SERIES

Virtual channels consist of one or more physical ATM links connected in a series for transmitting data between remote stations. ATM connects devices over a WAN using virtual channels (VCs) and virtual paths (VPs). This cell-based transmission is in contrast to typical local area network (LAN) variable-length packet mechanisms, which means that ATM connections are predictable and can be managed so that no single data type or connection can monopolize the transmission path.ĪTM technology originated in broadband ISDN (B-ISDN) technology and works primarily at layer 2 of the Open Systems Interconnection (OSI) reference model. The “transfer mode” in ATM refers to the fixed-size cell structure used for packaging information. The «asynchronous» in ATM means ATM devices do not send and receive information at fixed speeds or using a timer, but instead negotiate transmission speeds based on hardware and information flow reliability. The two main benefits of ATM are its high transmission speeds and its flexible bandwidth-on-demand capability. ATM networks use bandwidth at maximum efficiency while maintaining a guaranteed quality of service (QoS) for users and applications that require it. ATM is a connection-oriented protocol that can work with either permanent virtual circuits (PVCs) or switched virtual circuits (SVCs), depending on your wide area network ( WAN) traffic needs.

Backbone definition telecom