Syllabus Distribution (online)

• LIU Rules––

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Attendance policyExams

Academic Honesty

Withdrawal

Probations

In class behavior

• My rules– On time, honesty, hard working, reading

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Course outcomes

Identify the current approaches to design and implement broadband packet networks.

Outline the evolution of broadband networks generations.

Design a cost-effective network that meet the requirements of emerging technologies.

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• Explain the importance of broadbandmodern communication systems.

Learn the foundation and theory of theservice in modern networks.

networks for

• quality of

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Textbook and handouts

• Required text:– Connection-Oriented Networks: SONET/SDH,

ATM, MPLS, OPTICALG. Perros, Wiley 2005

QoS in Packet Networks,2005

NETWORKS Harry

– K. Park, Springer

• Handouts:– Will be delivered when needed

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Introduction

TOPICS––

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Overview of the Internet structure

Overview of the current networks implementation

Classification of communication systems

Examples of connections

Standards committees

1st generation of transport networks5

Example of a Road Network

Another road network

Internet Structure

6Source Kurose & Ross

Example of AT&T (Tier 1)

- Connects virtually every country and territory around the world.- More than 3,800 service nodes supporting MPLS-based services in 143 countries.- AT&T manages more than 200,000 MPLS customer ports.- A global carrier of IP and data traffic, carrying over 14,000 terabytes of traffic per average business day.- AT&T has one of the world's most powerful and advanced IP backbone networks, encompassing over 540,000

worldwide fiber-route miles - enough to circle the Earth at the equator more than 20 times.

Source http://www.telepresenceoptions.com/images/AT&T%20Network%20Map-thumb-450x227.jpg

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Another Global Network example

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Networks of our days

Direct FiberCOAX

Tier 2Fiber

Tier 2IP/

MPLSD ernetSONET/ S

TDMPON Fiber Tier 2

PBB-TE

S3/E3

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Ethernet

BondedT1/E1

Ethernet

Ethernet

Ethernet

Ethernet

Ethernet

Bonded Copper

Eth

Direct Fiber

Ethernet

EthernetEthernetEthernet

WDM

All-IP NetworksRegional office

CallManagerManager Router/GW

Router/GW

PSTN

HeadquarterIP WAN

DSL Access

InternetRouter/GW

VPN Access

Remote office

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Source www.cisco.com

Call

Current Evolution in Cellular NetworksMigration to the all-IP cellular networks

In 4G, there will be no circuit swiching

All data (voice, video, web, ftp, etc.) will use IP IP convergence

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Source Alcatel-lucent 2008

Classification of Communication Networks

EthernetPacket radio networkSatellite network

Telephone networkWavelength routing network

IP networkX.25ATMFrame relayMPLS

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Connectionless networksConnection-oriented networks

Packet–switched networksCircuit-switched networks

Broadcast communication networksSwitched communication networks

Communication networks

Switched communication networks

– Circuit-switched networks:• The telephone network (PSTN)• Wavelength routing optical network.

Packet-switched networks:–••••

IP networkATMFrame RelayMPLS networks

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Broadcast communication networks

• Examples:

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packet radio networkssatellite networks

multi-access Ethernet.

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Packet-switched networks

• Connection-oriented networks––

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ATMFrame Relay

MPLS

• Connectionless networks

– IP

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Circuit-switched networks

In order for two users to communicate a circuit or a connection has to be first established by the network. Specifically, thefollowing three phases are involved:––

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circuit establishment,data transfer,

circuit disconnect.

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Connection-orientedpacket-switched

networks

• Circuitvoice,

switching is a good solution forasince it involves exchanging

relatively continuous flow of data.

• However, it is not a good solution for thetransmission of bursty data

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Connection-oriented packet-switchednetworks imitate circuit-switched network.

In order for two users to communicate avirtual circuit or a connection has to be firstestablished by the network.three phases are involved:

The following

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connection establishment,data transfer, and

connection disconnect.

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Connectionlesspacket-switched networks

In an IP network, a user can send packets to a destination without having to set up a connection first, i.e., without informing the network prior to transmitting them.

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• This simplifies thea special signaling

network, as there is no need forprotocol.

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Routing in IP

User A User B

IP network

The routing of a packet through the network is doneon a hop-per-hop basis based on the destination IPaddress carried in the IP packet’s header.

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Quality of Service (QoS) in IP

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Typically, an IP router does not offer QoS.It cannot distinguish packets belonging to different service classes based on their destination address.IP is almost ubiquitous. There has been a lot of interest in introducing QoS in the IP network, and MPLS seems to be the architecture of choice for introducing QoS.

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Examples of connections

Probably the oldest connection-orientedcircuit-switched network is the plain oldtelephone system (POTS).

Switch Switch

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Twisted pair SONETTwisted pair

An ATM connectionATMATMATM

switch 1

switch 3switch 2

SETUPSETUP

SETUP

CONNECTCONNECT

CONNECT

A bi-directional connection is established using signaling.The connection is associated with an id number.

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SETUP

CONNECT

A B

• The switching of a cell through an ATM switch isdone based on its connection ID number.

A connection is associated with a specific class of service.

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• An ATM switch can distinguish cells belongingdifferent service classes, and serve them

to

accordingly so thatrequested QoS.

to provide them with the

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An MPLS connection

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The procedure is similar to ATM.

An MPLS-enabled IP router switches IP packets not on a hop-by-hop basis using the packet’s IP address. Rather, it forwards them using a label which identifies the connection that the packet has to follow.

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A wavelength routing opticalconnection

network

Router A OXC 1 OXC 2 OXC 3 Router B

1W1W 1W

A three-node wavelength routing network

Router A Router BOXC 1 OXC 2 OXC 3

A lightpath

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1 11 1

1W

• An important feature of a wavelengthrouting optical network is that it is a circuit-switched network.

A connection is an optical path through the•optical network (called a lightpath) and it is

hopestablished using a wavelengthalong the connection’s path.

on each

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Summary

connectionless (IP network)

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Circuit switchedPacket switched with

Call establishment Required Not required

Dedicated physical path Yes No

Packets follow the same path Yes No

Packets arrive in sequence Yes No

Breakdown in core equipment is fatal Yes No

Availabilty in bandwidth Fixed, constant Dynamic, variable

When the congestion can occur On call establishment On every packet

Bandwidth is fully utilized No Yes

Transmission Store-and-Forward No Yes

Billing Per minute Per packet

Standards Committees

ITU : International Telecommunication Union

ISO: International Organization for Standardization

ANSI: American National Standards Institute

IEEE: Institute of Electrical and ElectronicsEngineering

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IETF: InternetATM Forum

MPLS Forum

etc…

Engineering Task Force

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First Generation of TransportNetworks

TOPICS– History of the multiplexing

networksin circuit switched

– The PDH hierarchy

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PSTN History

• PSTN is the first telecommunicationnetwork (1875)– Based on circuit switched.

The subscriber is connected to the central office using a dedicated twisted pair (local loop).Multiplexing is done between two centraloffices to transport the calls of many users

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Multiplexing

• FDM (Frequency Division Multiplexing)used for analog signals.

TDM (Time division Multiplexing) used for digital signals PDH (Plesiochronous Digital Hierarchy)– How to digitize an analog signal (voice)?

WDM (Wavelength Division Multiplexing)used for optical signals

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First Step towards TDManalog signalDigitize the PCM (Pulse Code Modulation)

By sampling: take a sample every125 µsec.Then by quantification: represent the taken sample on 8 bits coding 8000 samples per seconde 8000 * 8 = 64 000 bits per second.

DS0 is the basic digital signal of 64 000 bits/sec34

TDM

• Time division multiplexing allowssimultaneously by many users

The transmission is organized into

a link to be utilized

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frames.

Each frame contains a fixed number of time slots.

Each time slot is pre-assigned to a specific input link. The duration of a time slot is either a bit or a byte.

If the buffer of an input link has no data, then its associated time slot is transmitted empty.A time slot dedicated to an input link repeats continuouslyframe after frame, thus forming a channel or a trunk.

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Hierarchical Multiplexing in TDM

Two approaches:•– PDH (Plesiochronous Digital Hierarchy)

• Plesion means “nearly the same”, and chronos means“time” in Greek)..

• Frame Format (Ex: European standard, Tx: NorthAmerican standard).

SONET/SDH (will be explained next week)• SONET: Synchronous Optical NETwork (North

American).

• SDH: Synchronous Digital Hierarchy (European).37

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Synchronous vs Plesiochronous

• Synchronous Digital Multiplexers have tributaries with thesame clock frequency, and they are all synchronized to a master clock SONET/SDH

Plesiochronous Digital Multiplexers have tributaries that have the same nominal frequency (that means there can be small difference from one to another), but they are not synchronized to each other PDH

For synchronous case, the pulses in each tributary all rise and fall during the same time intervalFor the PDH, the rise and fall time of the pulses in each

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•tributaries do not coincide with each other

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PDH: T carrier / E carrier

• The DS signal is carried over a carrierknown as the T carrier.– T1 carries the DS1 signal,

– T2 carries the DS2 signal etc…

system

• The ITU-T signal is carried oversystem known as the E carrier.

a carrier

• The DS and ITU-T hierarchy is known asplesiochronous digital hierarchy (PDH).

the

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The DS1 signal in T1

slot 24

• 24 (8-bit time slots)/frame– Each time slot carries 8 bits/ 125 µsec,

channel carries a 64 Kbps voice.or the

– Every 6th successive time slot (i.e, 6th, 12th,18th, 24th, etc), the 8th bit is robbed and it is used for signaling.

• F bit: Used for synchronization. It transmitsthe pattern: 101010110…

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FTime slot 1

Time slot 2

Time slot 3 . . .

Time

The DS1 signal in E1

• E1– 30 voice time slots plus

and control2 time slots for synchronization

– Total transmission rate: 32x8 = 256 bits per 125 sec,or 2.048 Mbps

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T1 frame for voice

24 time intervals, each one is composed of 8 bits (192 bits)

1 « Framing bit »8 bits per « timeslot » per DS1 frame

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T1 frame for data (fractional T1)It is possible to have a partial or an entire DS1•

• A partial DS1 allows to have multiple throughputsof 64kbps

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DS1, DS3 over SONET