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ECS5365 Lecture 4 Overview of B-ISDN. Philip Branch Centre for Telecommunications and Information Engineering (CTIE) Monash University http://www.anspag.monash.edu.au/~pbranch/masters.ppt. References.

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ECS5365 Lecture 4 Overview of B-ISDN

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ECS5365 Lecture 4Overview of B-ISDN

Philip Branch

Centre for Telecommunications and Information Engineering (CTIE)

Monash University

http://www.anspag.monash.edu.au/~pbranch/masters.ppt


References

  • Stallings, W., “ISDN and Broadband ISDN with Frame Relay and ATM”, 3rd Edition, Prentice-Hall, 1995

  • dePrycker, M., “Asynchronous Transfer Mode: Solution for Broadband ISDN”, 3rd Edition, Prentice-Hall, 1995

  • Partridge, C., “Gigabit Networking”, Addison-Wesley, 1994


Outline

  • Need for Broadband ISDN

  • B-ISDN applications

  • B-ISDN solution

  • B-ISDN layers

  • Physical layer

  • B-ISDN/ ATM Standards Bodies


What is Broadband-ISDN?

  • A Full Services Network (FSN)

  • Multiple services / one network

  • Integrates video, voice, data

  • Telco term more than Private network term


Need for B-ISDN

  • Limitations of N-ISDN

  • Statistical multiplexing

  • Scalable bandwidth

  • New applications

    • Video Applications

    • LAN-LAN connectivity networks

    • Quality of service


Quality of service

  • Different requirements for data, voice and video

  • Voice and video

    • low delay and delay variation

    • tolerant of loss

  • Data

    • tolerant of delay and delay variation

    • intolerant of loss


Scalable bandwidth

  • New applications bursty

  • Need bandwidth available on demand

  • Very fine units of bandwidth


Statistical multiplexing

  • Based on the Central Limit Theorem

  • Multiplex n independent and identically distributed random time varying signals

  • Mean of aggregate increases proportionally to n

  • Standard deviation of aggregate increases proportionally to sqrt(n)

    • variation of aggregate signal decreases proportionally as n increases


B-ISDN Driver Technologies

  • Optic Fibre (Photonics)

  • High performance PCs

  • Digital Signal Processing Chips

  • Sophisticated software


B-ISDN Services

  • Distributive

    • Broadcast

    • Multicast

  • Interactive

    • Messaging

    • Conversational

    • Retrieval


Examples of Distributive Services

  • Broadcast

    • Broadcast Television

  • Multicast

    • Near video-on-demand


Examples of Interactive Services

  • Messaging

    • video mail

  • Retrieval

    • video-on-demand

  • Conversational

    • video-conferencing


BISDN Design Decisions

  • Cell Switching

  • No feedback control

    • later changed

  • Sophisticated Quality of Service guarantees


Cell Switching

  • Connection oriented packet switching

  • Small uniform size packets

  • 48 byte payload, 5 byte header

    • compromise between 64 and 32 bytes

  • Advantage of cells

    • simple switch architectures

    • scalable bandwidth


Connection Oriented

  • Connection established end to end before transmission of data

  • ‘Virtual Circuit’ and Virtual Circuit Indicator

  • Lower delays during transmission

  • Connections can be blocked

  • Control over quality of service


Packet Switching

  • Information segmented for transmission and reassembled at destination

  • Information in packets

  • Each packet has a tag indicating destination

  • Packets from multiple calls statistically multiplexed

  • Can be delays caused by switch buffering


Asynchronous Transfer Mode

  • Fast packet switching technology

  • Cell relay

    • Small, fixed size packets (cells)

    • Segmentation and Reassembly

  • Connection Oriented

    • Virtual Circuit Indicator

  • Application Adaptation Layer protocols


No feedback control

  • Bandwidth time product

    • large number of bits in transit

  • Congestion events transient

  • Feedback control useless


Quality of Service

  • Defined in terms of

    • Cell loss rate

    • Delay

    • Delay variation

  • Need to know

    • Bit rates

    • Burstiness

  • QoS used in connection admission control


ATM’s Mixed Success

  • Quality of service a great success

  • Statistical multiplexing less successful

    • Data sources are not identically, independently distributed

    • Video has a periodic, rather than a random time varying nature

  • Data packets over cells easily causes congestion collapse

    • single cell loss causes whole packet to be discarded

  • Feedback control introduced in ABR


ATM Networks

  • ATM Switches

  • ATM to the desktop

  • Physical media


Broadband ISDN Protocol Reference Model

  • Higher Layers

  • ATM Adaptation Layer

  • ATM Layer

  • Physical Layer


Higher Layers

  • Application layer

  • Examples

    • Packets for IP network

    • Frames for HDLC network

    • Voice stream for telephony

    • MPEG transport stream for video


ATM Adaptation Layer

  • Maps higher layer to ATM cells

  • AAL for different applications

  • Segments and reassembles cells for ATM

  • Much more next lecture


ATM Layer

  • Cell relay switching technology

  • 53 Octets (bytes) cells

    • 5 byte header

    • 48 byte payload

  • Much more in later lectures


Physical Layer

  • ATM Transmission Media

    • Originally only 2 - 155 and 622 Mbps

    • analogous to Basic and Primary Rate Interface

    • New sublayers at different transmission rates


Transmission Rates

  • Plesiochronous Digital Hierarchy (PDH)

  • SynchronousOptical NETwork (SONET)

  • Synchronous Digital Hierarchy (SDH)

  • ATM to the desktop


PDH

  • E1 - 2 Mbps

  • E2 - 8 Mbps

  • E3 - 34 Mbps

  • E4 - 140 Mbps


Synchronous Optical Network (SONET)

  • STS-3 (OC-3) - 155 Mbps

  • STS-12 (OC-12) 622 Mbps

  • STS-48 (OC-48) 2.4 Gbit/s


Synchronous Digital Hierarchy

  • STM-1 155 Mbps

  • STM-4 622 Mbps

  • STM-16 2.4 Gbit/s


Desktop ATM

  • TAXI - 100 Mbps

    • FDDI based. Superseded

  • OC3 - 155 Mbps

    • Multimode fibre connection

  • STS-3 over UTP Category 5 - 155 Mbps

    • UTP Category 5

  • 25 Mbps UTP

    • Based on Token Ring interface


B-ISDN Standards Bodies

  • ITU - International Telecommunications Union

  • ATM Forum

  • IETF - Internet Engineering Taskforce


ITU Groups

  • SG9 - Television and sound transmission

  • SG11 - signalling and switching

  • SG13 - general network aspects

  • SG15 - transmission systems and equipment


ITU Recommendations

  • I.413 B-ISDN User Network Interface

  • I.432 B-ISDN UNI Physical Layers

  • I.361 B-ISDN ATM Layer Specification

  • I.363 B-ISDN ATM AAL Specification

  • I.371 Traffic and Congestion Control in B-ISDN


ATM Forum Specifications

  • LAN Emulation (LANE)

  • Traffic management v4.0

  • Private Network to Network Interface (PNNI) v.1

  • Physical Layers

  • User to Network Interface (UNI) v 3.1

  • UNI Signalling v 4.0

  • Multi-Protocol Over ATM (MPOA)


IETF RFCs

  • RFC1483 “Multiprotocol Encapsulation over ATM Adaptation Layer 5”

  • RFC1577 “Classical IP and ARP over ATM”


Summary

  • Need for Broadband ISDN

  • B-ISDN applications

  • B-ISDN solution

  • B-ISDN layers

  • Physical layer

  • B-ISDN/ ATM Standards Bodies


Reading for next week

  • Stallings Chapter 15 “ATM Protocols”


Review Questions

  • Why is connection admission control in B-ISDN more difficult than in N-ISDN?

  • Is ATM a layer 2 (data link) or layer 3 (network) protocol?

  • Why not overcome the time propagation delay problem by installing switches with large buffers?

  • Suppose we have a video sequence whose mean bandwidth is 1 Mbps and standard deviation is 0.5 Mbps. Assuming independence between the streams, what will be the mean and standard deviation of an aggregate stream consisting of 10 such sequences? 100? 1000?


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