VoATM

Last updated

Voice over Asynchronous Transfer Mode (VoATM) is a data protocol used to transport packetized voice signals over an Asynchronous Transfer Mode (ATM) network. [1] In ATM, the voice traffic is encapsulated using AAL1/AAL2 ATM packets. [2] VoATM over DSL is a similar service, which is used to carry packetized voice signals over a DSL connection. [1]

Contents

Protocols

Deployment

VoATM is a multi-service, high speed, scalable technology but rarely found because of its expensive services. [3]

Prioritization

Prioritization is implemented through QoS parameters. [3]

Fragmentation

Fragmentation is built into ATM with its small, fixed-sized, 53-byte cells. [3] [4]

Variable delay

Dynamic Bandwidth Circuit Emulation Service (DBCES) does not send a constant bit stream of cells but transmit only at an active voice call, reducing delays and variations. [3]

Echo cancellation

VoATM transports data, voice, and video at very high speed. The same method for echo cancellation is employed. [3]

See also

Professional wide band audio over ATM. Audio Engineering Society AES47

Related Research Articles

<span class="mw-page-title-main">Asynchronous Transfer Mode</span> Digital telecommunications protocol for voice, video, and data

Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by the American National Standards Institute and ITU-T for digital transmission of multiple types of traffic. ATM was developed to meet the needs of the Broadband Integrated Services Digital Network as defined in the late 1980s, and designed to integrate telecommunication networks. It can handle both traditional high-throughput data traffic and real-time, low-latency content such as telephony (voice) and video. ATM provides functionality that uses features of circuit switching and packet switching networks by using asynchronous time-division multiplexing.

In computer networking, cell relay refers to a method of statistically multiplexing small fixed-length packets, called "cells", to transport data between computers or kinds of network equipment. It is a reliable, connection-oriented packet switched data communications protocol.

Digital subscriber line is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed DSL technology, for Internet access.

A virtual circuit (VC) is a means of transporting data over a data network, based on packet switching and in which a connection is established within the network between two endpoints. The network, rather than having a fixed data rate reservation per connection, like in circuit switching, takes advantage of the statistical multiplexing on its transmission links. In addition, VCs standardized by the CCITT in 1976 impose per-connection flow controls at all user-to-network and network-to-network interfaces. They thus eliminate the need for the network to lose user packets in heavily loaded network zones, an intrinsic feature of datagram networks for their congestion control.

Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet telephony, broadband telephony, and broadband phone service specifically refer to the provisioning of communications services over the Internet, rather than via the public switched telephone network (PSTN), also known as plain old telephone service (POTS).

<span class="mw-page-title-main">Digital subscriber line access multiplexer</span> Network device that connects DSL interfaces to a digital communications channel

A digital subscriber line access multiplexer is a network device, often located in telephone exchanges, that connects multiple customer digital subscriber line (DSL) interfaces to a high-speed digital communications channel using multiplexing techniques. Its cable internet (DOCSIS) counterpart is the Cable modem termination system.

The Point-to-Point Protocol over Ethernet (PPPoE) is a network protocol for encapsulating Point-to-Point Protocol (PPP) frames inside Ethernet frames. It appeared in 1999, in the context of the boom of DSL as the solution for tunneling packets over the DSL connection to the ISP's IP network, and from there to the rest of the Internet. A 2005 networking book noted that "Most DSL providers use PPPoE, which provides authentication, encryption, and compression." Typical use of PPPoE involves leveraging the PPP facilities for authenticating the user with a username and password, predominately via the PAP protocol and less often via CHAP. Around 2000, PPPoE was also starting to become a replacement method for talking to a modem connected to a computer or router over an Ethernet LAN displacing the older method, which had been USB. This use-case, connecting routers to modems over Ethernet is still extremely common today.

In computer networking, the Point-to-Point Protocol over ATM (PPPoA) is a layer 2 data-link protocol typically used to connect domestic broadband modems to ISPs via phone lines. It is used mainly with DOCSIS and DSL carriers, by encapsulating PPP frames in ATM AAL5. Point-to-Point Protocol over Asynchronous Transfer Mode (PPPoA) is specified by The Internet Engineering Task Force (IETF) in RFC 2364.

The use of Asynchronous Transfer Mode (ATM) technology and services creates the need for an adaptation layer in order to support information transfer protocols, which are not based on ATM. This adaptation layer defines how to segment higher-layer packets into cells and the reassembly of these packets. Additionally, it defines how to handle various transmission aspects in the ATM layer.


In computer networking and telecommunications, a pseudowire is an emulation of a point-to-point connection over a packet-switched network (PSN).

Throughput of a network can be measured using various tools available on different platforms. This page explains the theory behind what these tools set out to measure and the issues regarding these measurements.

<span class="mw-page-title-main">Segmentation and reassembly</span> Process in telecommunications

Segmentation and reassembly (SAR) is the process used to fragment and reassemble variable length packets into fixed length cells so as to allow them to be transported across Asynchronous Transfer Mode (ATM) networks or other cell based infrastructures. Since ATM's payload is only 48 bytes, nearly every packet from any other protocol has to be processed in this way. Thus, it is an essential process for any ATM node. It is usually handled by a dedicated chip, called the SAR.

In computer networking and telecommunications, TDM over IP (TDMoIP) is the emulation of time-division multiplexing (TDM) over a packet-switched network (PSN). TDM refers to a T1, E1, T3 or E3 signal, while the PSN is based either on IP or MPLS or on raw Ethernet. A related technology is circuit emulation, which enables transport of TDM traffic over cell-based (ATM) networks.

AES47 is a standard which describes a method for transporting AES3 professional digital audio streams over Asynchronous Transfer Mode (ATM) networks.

The ideal telecommunication network has the following characteristics: broadband, multi-media, multi-point, multi-rate and economical implementation for a diversity of services (multi-services). The Broadband Integrated Services Digital Network (B-ISDN) was planned to provide these characteristics. Asynchronous Transfer Mode (ATM) was promoted as a target technology for meeting these requirements.

ATM Adaptation Layer 5 (AAL5) is an ATM adaptation layer used to send variable-length packets up to 65,535 octets in size across an Asynchronous Transfer Mode (ATM) network.

An edge device is a device that provides an entry point into enterprise or service provider core networks. Examples include routers, routing switches, integrated access devices (IADs), multiplexers, and a variety of metropolitan area network (MAN) and wide area network (WAN) access devices. Edge devices also provide connections into carrier and service provider networks. An edge device that connects a local area network to a high speed switch or backbone may be called an edge concentrator.

Multiprotocol Encapsulation over ATM is specified in RFC 2684. It defines two mechanisms for identifying the protocol carried in ATM Adaptation Layer 5 (AAL5) frames. It replaces RFC 1483, a standard data link access protocol supported by DSL modems.

<span class="mw-page-title-main">ADSL</span> DSL service where downstream bandwidth exceeds upstream bandwidth

Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. ADSL differs from the less common symmetric digital subscriber line (SDSL). In ADSL, bandwidth and bit rate are said to be asymmetric, meaning greater toward the customer premises (downstream) than the reverse (upstream). Providers usually market ADSL as an Internet access service primarily for downloading content from the Internet, but not for serving content accessed by others.

ATM Adaptation Layer 2 (AAL2) is an Asynchronous Transfer Mode (ATM) adaptation layer, used primarily in telecommunications; for example, it is used for the Iu interfaces in the Universal Mobile Telecommunications System, and is also used for transporting digital voice. The standard specifications related to AAL2 are ITU standards I.363.2 and I366.1.

References

  1. 1 2 Tamara Dean. Network+ Guide to Networks. Course Technology, Cengage Learning, 2010, p. 533.
  2. Cisco , Voice over ATM (VoATM)
  3. 1 2 3 4 5 Ahmed, Fatima. , developer.com, November 24, 2003, accessed April 26, 2011.
  4. AAL Types , accessed April 26, 2011