Topic 6 (Part 2) PUBLIC DATA NETWORK

DEPARTMENT OF ELECTRICAL ENGINEERING

EP601 DATA COMMUNICATION

TOPIC 6 : PART 2

At the end of this learning session, student must be able to;

Define SONET

Describe Synchronous Transport Signals (STS)

Explain SONET System

Explain NGN, Internet Protocol (IP), IPv4 and IPv6

Identify NGN characteristics

State type of NGN services

Introduction

What is SONET / SDH???

Synchronous Optical Network ANSI (US)

Synchronous Digital Hierarchy ITU-T Europe

Similar and compatible

A standard to be used for fibre optics

Recommendation for FOTS equipment

Fibre Optic Transmission Systems

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Introduction cont

SONET defines a hierarchy of electrical signaling levels called Synchronous transport signals (STSs)

SDH specifies a similar system called a synchronous transport module (STM).

It is another application of Time division Multiplexing (TDM).

That is a synchronous system controlled by master clock

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4

SONET Overview

The SONET specification defines:

standard optical signals, which permits the interoperation of equipment from different manufacturers

a synchronous frame structure for multiplexing digital traffic

procedures for operations and maintenance (OAM)

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SONET Overview Cont

SONET includes:

support for broadband rates

base rate approximately 50 Mbps

hierarchical family of digital rates

defines data rates up to 2.4 Gbps

synchronous multiplexing

global timing structure at physical layer

synchronous implies simpler interface 6

Signal Hierarchy

SONET : STS Synchronous Transport Signals

support a certain base data rate- 51.84Mbps

STS 1 STS 192 different hierarchies

Corresponding carrier System

Optical Carrier OC-1, OC-3, OC-12, OC-48

SDH : STM Synchronous Transport Module

STM 1 = STS 3

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SONET/SDH rates

The lowest level or base signal is referred to as STS -1 i.e. Synchronous Transport Signal level -1 which operates at 51.840Mbps.

Higher-level signals are integer multiples of STS -1.

STS N signal is composed of N byte-interleaved STS -1 signals.

An STS-1 and an STS-n frame

Each frame is a two-dimensional matrix of bytes with 9 rows

by 90 n columns.

Matrix of nine rows 90 octets = 90 bytes each

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STS-1 frames in transmission

Each synchronous transfer signal STS - n is composed of 8000 frames.

A SONET STS - n signal is transmitted at 8000 frames per second. Each byte in a SONET frame can carry a digitized voice channel.

SONET STS-1Frame

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Frame1

Frame2

Frame8000

Frame = 810 octets * 8 = 6480bits

8000 frames/sec = 6480*8000 bits/sec = 51.84Mbps

Each synchronous transfer signal STS - n is composed of 8000 frames.

Each frame is a two-dimensional matrix of bytes with 9 rows by 90 n columns.

Bytes (octets) are transmitted one row at a time, from left to right

Note: 1 byte/frame = 64 kbps

STS-1 frame overheads

Frame structure: 9 rows of 90 columns of 8-bit bytes First three columns of STS-1 frame are for section overhead and line overhead Remaining 87 columns are for the Synchronous Payload Envelope (SPE) 12

STS-1 frame: section overhead

Overhead bytes are used by SONET equipment (e.g., switches) for exchange of control and signalling information, and as a low bandwidth data channel.

Find the data rate of an STS-3 signal.

Solution

STS-3, like other STS signals, sends 8000 frames per

second. Each STS-3 frame is made of 9 by (3 90) bytes. Each byte is made of 8 bits. The data rate is.

Note : In SONET, the data rate of an STS-n signal is n times the data rate of an STS-1 signal.

Example

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17.

15

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What is the duration of an STS-1 frame? STS-3 frame?

STS-n frame?

Solution

In SONET, 8000 frames are sent per second. This

means that the duration of an STS-1, STS-3, or STS-n

frame is the same and equal to 1/8000 s, or 125 s.

Example

A simple network using SONET equipment

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STS multiplexers/demultiplexers - path terminating equipment : mark the beginning points and endpoints of a SONET link. - multiplex signals from multiple electrical sources and creates the corresponding optical signal and demultiplex an optical signal into corresponding electric signals.

- map user payload into standard frame - Header goes end-to-end as part of Synchronous Payload Envelope - SPE

SONET Devices

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SONET Devices cont

Add /Drop Multiplexers

- allow insertion and extraction of signals in an STS :

an add/drop multiplexer can add an electrical

signals into a given path or can remove a desired

signal from a path.

- use header address information to identify stream

and remove

- Line terminating Equipment

- perform multiplexing, synchronization, APS

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SONET Devices cont

Regenerator

- Repeater : improves signal quality by taking a

received optical signal and regenerates it.

- replaces some of the existing overhead information with new information.

- Operations include layer 2 : Frame alignment,

scrambling, error monitoring

- Section terminating equipment

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SONET

Section

Connects two neighboring devices

Line

Connects two multiplexers (STS , Add/Drop)

Path

Connects two STS Mux/demux

Layers likewise path, line, section

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SONET layers compared with OSI or the Internet layers

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SONET layers

Photonic layers

- corresponds to the physical layer of the OSI

model.

- physical specifications for the optical fiber channel.

- NRZ encoding used : the presence of light

representing 1 and the absence of light

representing 0

Power level

Wavelength

Pulse shape

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Section layer

is responsible for the movement of a signal across a physical section.

Frames : identifies beginning of frame

Scrambling : introducing 1s to derive clock

error monitoring : at section level

Adds 9 bytes to header : frame size 810 bytes

Provided at all devices 23

SONET layers cont

Line layer

is responsible for the movement of a signal across a physical line.

Locates partial payload virtual tributaries

Provides frequency justification, bit stuffing

To adjust to clocking from different systems

Does APS

Adds 18 bytes to header

Provided at the STS Mux and Add/Drop Mux

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SONET layers cont

Path layer

is responsible for the movement of a signal from its source to its destination.

Converts to optical signals and back to electromagnetic

Adds 9 bytes to header - is part of SPE

Defines the payload being carried

End-to-end path control

Support virtual tributaries

Provided at the STS Mux 25

SONET layers cont

Devicelayer relationship in SONET

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The next-generation network (NGN) is a body of key architectural changes in telecommunication core and access networks.

The general idea behind the NGN is that one network transports all information and services (voice, data, and all sorts of media such as video) by encapsulating these into packets, similar to those used on the Internet.

NGNs are commonly built around the Internet Protocol, and therefore the term all IP is also sometimes used to describe the transformation toward NGN.

NEXT GENERATION NETWORK

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ITU-T definition of NGN (Feb 2004)

A Next Generation Network (NGN) is a packet-based network

Able to provide services including Telecommunications Services and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies.

It offers unrestricted access by users to different service providers.

It supports generalized mobility which will allow consistent and ubiquitous provision of services to users.

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1990 1980 1970

NGN Long-Term Network Convergence Perspective

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Public Switched Telecommunication Network (PSTN)

Intelligent Network Internet (IN)

Open Systems Interconnection Internet (OSI)

Commercial Mobile Radio Systems

2000

NGNs

IP Internet (IP) private quasi-public

Was never designed

as public

infrastructure

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Telephone

Services

Data

Services

(WWW,

e-mail, etc)

Video

Services

(TV, movie, etc)

Telephone

Services

Network

Video

Services

Network

Data

Services

Network

Pre-NGN

Policy Area 1 Policy Area 2 Policy Area 3

Legacy: Vertically-Integrated Networks

Transport

Services

Telephone Services

Data Services (WWW, e-mail, etc)

Video Services (TV, movie, etc)

Point to point, Point to multipoint, Multipoint to

multipoint

Point to point, Point to multipoint, Multipoint to

multipoint

NGN - Convergence

NGN: Horizontally-Integrated Network

In an NGN, two separate policy frameworks are required: one applicable to transport networks, and another applicable to content-based services.

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Internet Protocol

(IP)

Anything & Everything

Everything

Two Policy Domains

(Any & All Network technologies)

(Any/All Applications

e.g. voice , data , video)

NGN: Shape of things to come

Scope Of

Internet

Services

Transport

Note :

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One network for everything

Today Tomorrow

Telephone network

Mobile radio network

IP-Network

Multimedia Access - Advantages: easy to handle reliable mobile

Internet

Transition to NGN

IP will become the networking protocol

of choice.

Internet Protocol (IP)

What is IP?

The Internet Protocol (IP) is the method or protocol by which data is sent from one computer to another on the Internet.

When IP was first standardized in Sep 1981, each system attached to the IP based Internet had to be assigned a unique 32-bit address.

IPv4, defines a 32-bit address - 232

(4,294,967,296) IPv4 addresses available

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IP Address Shortage

Proliferation of Internet devices:

405M mobile phones sold in 2000

1B+ by 2005

New emerging populations:

China, Korea, Japan, India, Russia

Solution = IPv6

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Address Formats

IPv4

32-bit

Ex: 192.156.136.22

IPv6

128 bits

Ex: 1080:0:0:0:8:800:200C:417A

Or in compressed format:

1080::8:800:200C:417A

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8 groups of 16-bit hexadecimal numbers separated by :

:: = all zeros in one or more group of 16-bit hexadecimal numbers

128 bits 32 bits

IPv4 & IPv6 Header Comparison

Version IHL Type of Service

Total Length

Identification Flag

s Fragment

Offset

Time to Live

Protocol Header Checksum

Source Address

Destination Address

Options Padding

Version Traffic Class

Flow Label

Payload Length Next Header Hop Limit

Source Address

Destination Address

IPv4 Header IPv6 Header

- fields name kept from IPv4 to IPv6

- fields not kept in IPv6

- Name & position changed in IPv6

- New field in IPv6 Le

ge

nd

The basic IPv4 packet header has 12 fields with a total size of

20 octets (160 bits).

20

octe

ts

The basic IPv6 packet header has 8 fields with a total size of 40 octets (320 bits).

40

octe

ts

Major Improvements of IPv6 Header

No option field: Replaced by extension header. Result in a fixed length, 40-byte IP header.

No header checksum: Result in fast processing.

No fragmentation at intermediate nodes: Result in fast IP forwarding.

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Advantages to IPv6

Larger address space

Reduce end-to-end delay

Higher level of security (IPSec Mandated, works End-to-End )

Mobility (Mobile IP with Direct Routing)

No fragmentation

Network autoconfiguration (Serverless, Reconfiguration, DHCP

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Basic characteristics of NGN

Packet-based transfer,

Separation of control functions

Decoupling of service provision

Support for a wide range of services

Broadband capabilities

Interworking with legacy networks

Generalized mobility

Unfettered access 40

NGN Services

Several services that will be important drivers in the NGN environment are:

1-Voice Telephony: e.g.Call Waiting, Call Forwarding, 3-Way Calling

2-Voice Portal: provide callers with anywhere, anytime access to information like news, weather, stock quotes, and account balances using simple voice commands and any telephone,..

3-Data services: bandwidth-on-demand, connection reliability/resilient ,

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4-Multimedia services: This allows customers to converse with each other while displaying visual information.

5-Virtual Private Networks: allow large, geographically dispersed organizations to combine their existing private networks with portions of the PSTN, thus providing subscribers with uniform dialing capabilities.

6-Public Network Computing: Provides public network-based computing services for businesses and consumers (e.g, to host a web page, store/maintain/backup data files, or run a computing application).

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NGN Services cont

7-Unified Messaging: Supports the delivery of voice mail, email, fax mail, and pages through common interfaces .

8-Information Brokering: Involves advertising, finding, and providing information to match consumers with providers.

9-E-Commerce: Allows consumers to purchase goods and services electronically over the network.

10-Call Center Services: A subscriber could place a call to a call center agent by clicking on a Web page.

11-Interactive gaming: Offers consumers a way to meet online and establish interactive gaming sessions. 43

NGN Services cont

12-Distributed Virtual Reality: Refers to technologically generated reperesentations of real-word events, people, places,experiences, etc., in which the participants in and providers of the virtual experience are physically distributed.

13-Home Manager: These services could monitor and control home security systems, energy systems, home entertainment systems, and other home appliances.

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NGN Services cont

REFERENCES:

Main: Forouzan, B.A. (2012). Data Communications and Networking (5th edision). Mc Graw Hill. (ISBN: 978-0-07-131586-9) Additional: William Stallings. (2011). Data And Computer Communication (9th edition). Prentice Hall. (ISBN-10: 0131392050)