ATM BASICS - Chapter 6 pptx

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Chapter 6

Where is ATM Used Today

This chapter presents the most commonly used ATM applications. It identi￾fies market segments as well as operators using ATM infrastructure. The

chapter provides basic information referring to the transmission of IP pack￾et over ATM networks. It also covers some of the ATM and Frame Relay

interworking aspects. Finally, the reader is given the short introduction to

different solutions for transmission of voice services using ATM infrastruc￾ture

Over last ten years a number of new technologies have become commercial￾ly available. The developments in transmission technologies such as the

ability to transmit data at different wavelengths (DWDM) combined with

the introduction of techniques such as Gigabit and 10Gbit Ethernet changed

the market situation. Additionally, the advent of MPLS and advances in

QoS based routing in IP network highly influenced the position of ATM.

In the public network segment, ATM is important for services delivery, ser￾vice aggregation and transport. It is a well-defined worldwide standard that

has been widely deployed because it works and it is not only for data. This

technology is embedded into carrier edge and backbone infrastructures to

support enterprise-class applications with high reliability. In fact reliability

is the key ATM advantage when compared to all–IP based solutions.

Despite the fact that some ISPs and data-only carriers treat ATM as a data

transport solution, ATM is actively used to provision voice and TDM ser￾vices, and handles a significant amount of frame relay and IP services traf￾fic. It is also the primary technology used for DSL traffic aggregation and is

used to feed traffic into other service backbones like PON (Passive Optical

Network). On the other hand ATM has clearly received a more favorable

reception in service provider networks, where its first mission was to pro￾vide a scalable core for fast-growing frame relay networks. Large carriers

are looking for solutions that let them continue to deploy proven and legacy

services generating most revenue, e.g. voice, frame relay and private line. In

fact, the capital markets are driving them to this conclusion. At the same

time, there are ongoing efforts to prepare the networks for an eventual

transition to an IP core.

In addition it is important to note that ATM makes a lot of sense for multi￾service delivery in access networks, since it has the ability to deliver voice

via its CBR service, as well as data via VBR and UBR. ATM remains the

most cost-effective method for transporting real-time traffic at OC-12 rates

and below. This is proven by the number of wireline and wireless voice car￾riers who use ATM to transport their voice traffic.

Concluding, it is possible to identify a few applications that currently domi￾nate as far as the usage of ATM is discussed. The first and probably the one

that would decline in next few years is the transmission of IP packet over

ATM (IP over TM). The second is ATM and Frame Relay interworking used

at large scale by carriers offering Frame Relay services. Last but no least,

the growing popularity Voice over ATM solutions would be also covered.

There are also many other ATM applications but their market penetration

is today relatively small and either they have already found strong com￾petitors or they would be replaced soon by solutions mostly based on IP plat￾forms. They include mainly applications using SVC services such as: multi￾media, Video Dial Tone and Conferencing Service, Interworking with exist￾ing LANs (LANE), Campus/Corporate Enterprise Networks (MPOA).

ATM Basics

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