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CommServ Education Division Datacom Networking Introduction-1 Data Communication Transport

EduDivision-DATACOM NETWORKING

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Page 1: EduDivision-DATACOM NETWORKING

CommServ – Education Division Datacom Networking Introduction-1

Data Communication Transport

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CommServ – Education Division Datacom Networking Introduction-2

Introduction

• Name, Company and Location

• Job Title and Responsibilities

• Related Work Experience

• Course Expectations

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CommServ – Education Division Datacom Networking Introduction-3

Course Prerequisites

• There are no prerequisites for this course.

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CommServ – Education Division Datacom Networking Introduction-4

Course Materials

• Course Manual

• Evaluation Form

• Reference Materials

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CommServ – Education Division Datacom Networking Introduction-5

Course Objectives

• To gain a solid understanding of modern data

communications technologies and concepts

• Technologies covered:

– TCP/IP, Ethernet, ATM, Frame Relay, X.25, PPP, Modems,

ISDN, xDSL, SDH/SONET, Packet-over-SONET, MPLS

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Course Schedule

•Day 1: PRE-TEST, Standards, Physical Media, Datacom Concepts

& Traffic Cases

•Day 2: Ethernet Concepts, Ethernet Frame Types & Devices

Fast & Gigabit Ethernet

•Day 3: WAN Concepts, ATM and Frame Relay

•Day 4: WAN Concepts, X.25, Point-to-Point Protocol, Modems,

ISDN, xDSL, PDH/SDH/SONET, Packet-Over-SONET, MPLS

•Day 5: Internet Architecture & Applications, Transport Layer,

Protocols, Internet Protocol & IP Addressing, Internet Routing &

Dynamic Routing

POST TEST

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CommServ – Education Division Datacom Networking Introduction-7

Modern Datacom Networking

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CommServ – Education Division Datacom Networking Standard-8

Datacom Networking 2. Standardization and the OSI Model

Chapter Objectives

–Identify the standards bodies associated with data

communications

–Describe in detail the OSI reference model

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Standard Bodies

Frame Relay Forum

IEEE

ITU

ISO

ANSI

IETF

ATM Forum

ETSI

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International Telecommunications Union (ITU)

ITU-R

Study Group Study Group

ITU-T ITU-D

ITU

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ITU-T Recommendations

Function Series

Public data communication network X-

Digital communication over the telephone network V-

Telephone switching and signalling networks Q-

ISDN I-

International telephone connections and circuits G-

Telephone network and ISDN E-

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Standards Organizations

• International Telecommunications Union

– www.itu.int

• International Standards Organisation

– www.iso.ch

• American National Standards Institute

– www.ansi.org

• European Telecommunications Standards Institute

– www.etsi.org

• Electronic Industries Alliance

– www.eia.org

• Internet Engineering Task Force

– www.ietf.org

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Standards Organizations

• Frame Relay Forum

– www.frforum.com

• Institute of Electrical and Electronics Engineers

– www.ieee.org

• International Multimedia Teleconferencing Consortium

– www.imtc.org

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OSI Reference Model

• The Open System Interconnection (OSI) Reference Model is a concept that describes how data communications should take place

• It divides the process into seven groups, called layers

• Protocol standards developed by the ISO and other standards bodies are fitted into these layers

• The OSI model is not a single definition of how data communications actually takes place in the real world, Numerous protocols may exist at each layer

• The OSI model is old, but it’s important because modern functionality is defined using the language of the OSI model, for example “layer 2 forwarding”

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OSI Reference Model Layers

Transmits and receives on the network medium Physical 1

Transfers units of information to the other end

of the physical link Data Link 2

Switches and routes information to the

appropriate network device Network 3

Provides end-to-end data integrity and reliable

delivery of data Transport 4

Co-ordinates interaction between end-to-end

application processes Session 5

Provides code conversion and data

reformatting Presentation 6

Interfaces directly with application programs

running on the devices Application 7

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The Physical Layer

TDM / FDM / WDM Multiplexing

Baseband

Broadband Bandwidth Usage

Asynchronous

Synchronous

Bit

Synchronisation

Current State Signalling

Bus, Ring, Cellular Physical Topology

P-2-P , P-2-MP Connection Types

Physical

Methods Function Layer

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The Datalink Layer

DLC

Physical

device Addressing

Contention

Token passing

Media access

services

Bus

Ring Logical topology

MAC

Flow control

Error control Connection services

Asynchronous

Synchronous

Transmission

Synchronisation LLC

Methods Function Sub layer

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Network Layer

Static

Dynamic Route Selection

Distance Vector

Link State Route Discovery

Packet Switching Switching

Logical Network

Services Addressing

Network

Method Function Layer

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Routing

6 5 4

3

2

3

3 2

1 1

1

3

2

3 2 4

5 6 1

4

5

6

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Transport Layer

Service requester

initiated

Address/Name

Resolution

Segment sequencing

Error control

End-2-End flow control

Connection services

Segmentation and

Reassembly (SAR) Segment development

Connection identifier

Transaction identifier Addressing Methods

Transport

Method Function Layer

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Session Layer

• Session layer facilitates and controls communication sessions between service providers and service requesters

• The session layer has functions to establish maintain, synchronise and manage communication sessions

• Often, it also helps the upper layers identify and connect to the services available on the network.

• The two main session layer tasks are:

• Dialogue control

• Session administration

• This includes the control and management of multiple bidirectional messages so that the application can be notified if only some of a series of messages are completed.

• For example, an Automated Teller Machine transaction in which you get cash out of your checking account should not debit your account and fail before handing you the cash, and then record the transaction even though you did not receive money.

• RPC, SQL, NFS, NetBios names, AppleTalk ASP, DECnet SCP

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Presentation Layer

• This layer’s main purpose is defining data formats, such as ASCII text, EBCDIC text, binary, BCD, and JPEG.

• Encryption is also defined by OSI as a presentation layer service.

• For example, FTP allows you to choose binary or ASCII transfer. If binary, the sender and receiver do not modify the contents of the file. If ASCII is chosen, the sender translates the text from the sender’s character set to a standard ASCII and sends the data. The receiver translates back from the standard ASCII to the character set used on the receiving computer.

• Example: TIFF, GIF, JPEG, PICT, ASCII, EBCDIC, encryption, MPEG, MIDI, HTML

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Presentation Layer

The presentation layer’s main functions are:

• Translation • Code conventions

• Bit/Byte order

• File syntax

• Encryption / Decryption

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Application Layer

• Provides interface to end user process and applications

• Takes care of all the requests made by the running applications

• An application that communicates with other computers is implementing OSI application layer concepts. The application layer refers to communications services to applications. For example, a word processor that lacks communications capabilities would not implement code for communications, and word processor programmers would not be concerned about OSI Layer 7. However, if an option for transferring a file were added, then the word processor would need to implement OSI Layer 7 (or the equivalent layer in another protocol specification).

• Examples: FTP, WWW browsers, Telnet, NFS, SMTP gateways (Eudora, CC:mail), SNMP, X.400 mail, FTAM

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Data Transmission

Bits

S-Data unit

T-Data unit

Packet

Frame

Bits

P-Data unit

A-Data unit Data A

Data

Physical

Data Link

Network

Transport

Session

Presentation

Application

Data A P

Data A P S

S Data A P T

T S Data A P N

N T S Data A P D D

101101111000101011010010101010

Pro

toco

l S

tack

Data unit

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Example: HTTP

Web Browser

Physical

Data Link

Network

Transport

Session

Presentation

Application

Ethernet

IP

TCP

HTTP

Web Server

Ethernet

IP

TCP

HTTP

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OSI and Network Devices

Physical

Data Link

Network

Transport

Session

Presentation

Application

Physical

Data Link

Network

Transport

Session

Presentation

Application

Repeater

Bridge

Router

Hub

Switch

Router

User

Application

User

Application

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OSI and Network Devices

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OSI Layers: Network Interaction

Physical

Data Link

Network

Transport

Session

Presentation

Application

Physical

Data Link

Network

Transport

Session

Presentation

Application

User

Application

User

Application

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OSI Model Summary

Concerned with transmission of unstructured bit stream over physical medium; deals with the mechanical, electrical, functional and procedural characteristics to access the physical medium.

1) Physical

Provides for the reliable transfer of information across the physical link.

Establishes a physical link, sends blocks of data (frames) in the proper

format, along with the necessary synchronization, error control, and flow

control.

2) Data Link

Provides upper-layers with independence from the data transmission and switching technology used to connect systems. Concerned with routing packets, congestion control, fragmentation, and reassembly.

3) Network

Provides reliable, transparent transfer of data between end points.

Provides end-to-end error recovery and flow control. 4) Transport

Provides the control structure for communication between applications.

Establishes, manages and terminates connections (sessions) between

applications. 5) Session

Provides data representation (Syntax) independence to the

application process. 6) Presentation

Access to the OSI environment for user applications and processes. 7) Application

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Datacom Networking 3. Physical Media

Chapter Objectives –Describe the characteristics of coaxial cable, UTP, STP and optical fiber

–Describe the terms DCE and DTE

–Describe the characteristics of RS232, RS422, V.35, V.36 and X.21

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Physical Media

• Co-axial

• Twisted Pair

– Unshielded

– Shielded

• Optical Fiber

– Single Mode

– Multimode

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Typical Coaxial Cable

BNC Connectors

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BNC T-Connector

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Characteristics of Coax

• Medium cable costs

• Simple to install

• Moderate installation costs

• Moderate EMI

• High bandwidth

• Often used as backbone cable

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Unshielded Twisted Pair

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Characteristics of UTP

• Lowest cost

• Very simple to install

• Low installation costs

• Highest electromagnetic interference (EMI)

• Lowest in bandwidth

• Used in more than 99% of LANs

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Categories of UTP for Networks

• Category 3 (Cat 3)

– Bandwidth 16 Mhz

– Data transmission function

– 11.5 dB attenuation

– 100 ohms Impedience

– Used with 10baseT (10Mbps), IBM token ring (4Mbps), ARCnet, 100VG-AnyLAN (100 Mbps)

• Category 4 (Cat 4)

– 20 MHz Bandwidth

– Data transmission function

– 7.5 dB Attenuation

– 100 ohms Impedance

– Used with 10baseT (10Mbps), IBM Token ring, ARCnet, 100VG-AnyLan (100 Mbps)

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Categories of UTP for Networks (2)

• Category 5 (Cat 5)

– 100 MHz Bandwidth

– Used for high-speed data transmission

– 24.0 dB Attenuation

– 100 ohms Impedance

– Used with 10BaseT (10 Mbps), IBM Token ring, Fast Ethernet, (100 Mbps), Gigabit Ethernet (1000 Mbps), ATM (155 Mbps)

• Category 5 Enhanced (Cat 5E)

– 100 MHz Bandwidth

– Transmits high-speed data

– 24.0 dB Attenuation

– 100 ohms Impedance

– Used with 10BaseT (10 Mbps), IBM Token Ring, Fast Ethernet (100 Mbps), Gigabit Ethernet (1000 Mbps), ATM (155 Mbps)

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Categories of UTP for Networks (3)

• Category 6 (Cat 6)

– 250 MHz Bandwidth

– Transmits high-speed data

– 19.8 dB Attenuation

– 100 ohms Impedance

– Used with 10BaseT (10 Mbps), IBM Token Ring, Fast Ethernet (100 Mbps), Gigabit Ethernet (1000 Mbps), ATM (155 Mbps)

• Category 6 Enhanced (Cat 6E)

– 250 MHz Bandwidth

– Transmits high-speed data

– 19.8 dB Attenuation

– 100 ohms Impedance

– Used with 10BaseT (10 Mbps), IBM Token Ring, Fast Ethernet (100 Mbps), Gigabit Ethernet (1000 Mbps), ATM (155 Mbps)

• Category 7 (Cat 7-NOT YET APPROVED)

– 600 MHz Bandwidth

– Transmits high-speed data

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Shielded Twisted Pair

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Characteristics of STP

• Medium cable costs expense

• Simple to moderate installation difficulty

• Moderate installation costs

• Moderately low EMI

• Moderate band width

• Usually found in older networks

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Optical Fiber

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Single Mode and Multimode Fiber

• Single Mode Fiber

– Small core diameter which only allows one mode (ray) of light to propagate through the fiber

– Used for applications with long transmission distances (carrier core networks)

• Multimode Fiber

– Larger core diameter which allows many modes of light to propagate through the fiber

– Larger core diameter facilitates use of cheaper components

– Used primarily for applications with short (<2Km) transmission distances (campus backbones)

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Characteristics of Fiber

• Highest cable costs

• Difficult to install

• Highest installation costs

• No EMI

• Very high bandwidth

• Uses light rather than electrical signals

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DCE Vs DTE

DCE DCE

DTE DTE

V.24,

V.28,

Client/Calling Server/Called/ Modem Answer Modem

PSTN

V.24,

V.28,

V.90/V.34/V.32

V.42/V.42bis

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Physical Layer Standards

RS-232C (EIA) / V.24 (ITU)

generator receiver A

B common ground pin 7

RS232C (V.24, V.28)

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Physical Layer Standards (contd)

generator receiver

A

B

RS422 (V.11, X.27) R

RS-422 (EIA) / V.11 (ITU)

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Data Rate vs. Cable Length

100

1k

10k

cable

length

(feet)

50

10

Data Rate - bps

100 1k 10k 100k 1M 10M

RS-232

4k

RS-422

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V.24/V.28, RS232c Interface

ISO 2110 Connector

1 13

14 25

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9 - 25 pin D Cable

PC 9 Pin Modem 25 Pin Function in the PC

3 2 TxD Transit Data

2 3 RxD Receive Data

7 4 RTS Request to Send

8 5 CTS Clear to Send

6 6 DSR Data Set Ready

5 7 SG Signal Ground

1 8 DCD Carrier Detect

4 20 DTR Data Terminal Ready

9 22 RI Ring Indicator

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V.24 Interface Circuits Pin V.24 RS232c DTE DCE EIA Description

1 101 AA FG Protective Ground

2 103 BA X TxD Transmit Data

3 104 BB X RxD Receive Data

4 105 CA X RTS Request to Send

5 106 CB X CTS Clear to Send

6 107 CC X DSR Data Set Ready

7 102 AB SG Common Return / Signal

Ground

8 109 CF X DCD Data Carrier Detect

15 114 DB X TC Transmit Timing Clock

17 115 DD X RC Receive Timing Clock

20 108 CD X DTR Data Terminal Ready

22 125 CE X RI Ring Indicator

24 113 DA X TC External Transmit Timing

Clock

Other pins not shown used used in some modem circuits only.

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Null Modem Cable 25 pin to 25 pin D

Pin Signal

7 Signal

Ground

2 Transmit

3 Receive

4 RTS

5 CTS

20 DTR

6 DSR

8 DCD

Signal Pin

Signal Ground

7

Transmit 2

Receive 3

RTS 4

CTS 5

DTR 20

DSR 6

DCD 8

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Pin Signal

5 Signal

Ground

3 Transmit

2 Receive

7 RTS

8 CTS

4 DTR

6 DSR

1 DCD

Signal Pin

Signal Ground

5

Transmit 3

Receive 2

RTS 7

CTS 8

DTR 4

DSR 6

DCD 1

Null Modem Cable 9 pin to 9 pin D

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V.35 Interface

KK EE AA W S M H C

MM HH CC Y U P K E A

LL FF BB X T N J D

DD JJ NN Z V R L F B

ISO 2593 Connector

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V.35 Interface (contd)

ITU-T No. Circuit Pin Number Source Source Designation

DTE DCE

102 GND B Signal Ground

103 TXD P , S X Transmit Data a,b

104 RXD R , T X Receive Data a,b

105 RTS C X Request to Send

106 CTS D X Clear to Send

107 DSR E X Data Set Ready

108.1 DTR H X Data Terminal Ready

109 DCD F X Data Carrier Detect

113 TCX U , W X Transmit Signal timing a,b from DTE

114 TXC Y , AA X Transmit Signal timing a,b to DTE

115 RXC V , X X Receive Signal timing a,b to DTE

140 RL N X Remote Digital Loop

141 LL L X Local Loop

142 TST NN X Test Indicator

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V.36 Interface

1 19

37 20

ISO 4902 Connector

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X.21 Interface

1 8

9 15

ISO 4903 Connector

ITU-T. Pin Number Source Source Designation

circuit DTE DCE

G 8 Signal Ground

T 2, 9 X Transmit Data a,b

R 4, 11 X Receive Data a,b

C 3, 10 X Control a, b

I 5, 12 X Indication a, b

S 6, 13 X Signal element timing a, b

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RJ 45 Ethernet

Pin Name Description 568A 568B

1 TD + Transmit Data + White/Green White/Orange

2 TD - Transmit Data - Green Orange

3 RD + Receive Data + White/Orange White/Green

4 n/c Not connected Blue Blue

5 n/c Not connected White/Blue White/Blue

6 RD - Receive Data - Orange Green

7 n/c Not connected White/Brown White/Brown

8 n/c Not connected Brown Brown

Note 1 Cable has four pairs. White/Green and Green are a pair etc.

Note 2 TD & RD are swapped on Hub's.

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Pin Function Required

TE NT

1 Power source 3 + Power sink + No

2 Power source 3 - Power sink - No

3 Transmit +

4 Receive +

5 Receive -

6 Transmit -

7 Power sink 2 - Power source 3 - No

8 Power sink 2 + Power source 3 + No

Note: Power source 2 and 3 are not mandatory and may only be

available from some NT or TE devices.

RJ 45 ISDN BRI s/t Interface

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RJ 48c

Pin Description

1 Receive Ring

2 Receive Tip

3 Not connected

4 Transmit Ring

5 Transmit Tip

6 Not connected

7 ground for transmit screen

8 ground for receive screen

E1 / T1 Balanced/Unbalanced

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SC Connectors

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ST Connectors

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Datacom Networking 4. Datacom Fundamental

Chapter Objectives –Define LANs and WANs

–Identify multiplexing, transmission, and error control methods

–Describe common network topologies

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Network Definition - LAN / WAN

Local Area Networks

(LANs)

Router A Router B

Wide Area Network

(WAN)

Token Ring

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Bandwidth Usage

• Baseband

all the available bandwidth is used to derive a single transmission path

• Broadband

the total available bandwidth of the cable is divided into a number of lower bit rate channels, which can transmit many simultaneous signals

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Modulation / Demodulation

• Amplitude Modulation

where the Amplitude of the signal is varied

• Frequency Modulation

where the Frequency of the signal is varied

• Phase Modulation

where the Phase of the signal is shifted

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Digitization

• Is the Process of Converting an Analog Signal to Digital Format

• A COder-DECoder performs this operation by applying Pulse Code Modulation algorithm

• The CODEC may be placed at any point

• A logarithmic (com-panding) scale is used to map the amplitude to its digital value

• The PCM companding rules define:

255 amplitude levels, -law, in USA, Canada and Japan

256 amplitude levels, A-law, almost rest of the world

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Multiplexing Techniques

• Time Division Multiplexing (TDM)

– Conventional

• Bit-Interleaved

• Byte-Interleaved – Statistical (STDM)

T S - 1

t

f

T S - 2 T S - 3 T S - 4 T S - 1 T S - 2 T S - 3 T S - 4 T S - 1 T S - 2 T S - 3 T S - 4TDM

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Multiplexing Techniques

• Frequency Division Multiplexing (FDM) (CATV is a good example)

• Wavelength Division Multiplexing (WDM)

(often used in optical data transmission)

t

f

F C - 1

F C - 2

F C - 3

F C - 4

FDM

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Communication Modes

• Simplex

– data is transmitted in one direction only

• Half Duplex

– Data can be transmitted in both directions, but only in one direction at any given time

• Full Duplex

– Data is transmitted in both directions simultaneously

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Transmission Modes

SYN character Bit stream of many characters

Asynchronous

Synchronous

SYN character

Stop bit Character Start bit

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Asynchronous communications

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Synchronous Transmission

• The complete block of data is transmitted as a contiguous bit stream in frames

• To enable the receiving device to stay in sync data is carefully encoded (bit sync)

• frames are preceded by a reserved byte to ensure correct interpretation on byte boundaries (byte sync)

• frames are preceded by synchronization bytes (frame sync)

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Error Control

• Parity Bit Method

– an additional bit is added to each tansmitted character to detect single bit errors

• Even / Odd parity

• Block sum check algorithms

– two additional bits are added (row / column) to detect errors

– two bit errors that escape the row parity checking, will be detected by this method

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Error Control

Frame to be transmitted Calculated CRC value

f Input data Output data

Input

poly

nom

ial

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Data Compression

• Packed Decimal

– Reduce the number of transmitted data (numbers 0-9 all have 011 in msb position)

• Relative Encoding

– Data that has only small differences between successive values, (send only the d-magnitude)

• Character Suppression

– Used for more general case

• Huffman Coding

– Statistical coding

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Network Topologies

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Protocols

• A protocol is a set of rules that govern the behaviour of communicating parties

• Protocols handle:

Format of the exchanged data

Type and order of the information

Timing

Sequencing

Error control

Flow Control

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Datacom Networking 5. Traffic Case

Chapter Objectives

–Describe at a high level the path a packet may take through a

network

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So, what happens when you do this?

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Upper Layer Protocol into IP

• This is the File Transfer Protocol (FTP), which is a higher-

layer protocol (layers 5,6 & 7 of OSI model)

• FTP is carried within an Internet Protocol (IP) packet

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Local Area Network Technologies

• Your PC is connected to your office Local Area Network

(LAN), through a Network Interface Card (NIC)

• Typically, the LAN technology used is Ethernet

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Adapting IP to Ethernet

• The information (IP) needs to be adapted to the network technology

• In this case the information must be transmitted in Ethernet frames

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The Hub

• Likely the first device your frame will encounter is a hub – an Ethernet repeater

• This hub simply repeats the signal and sends it on

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The LAN Switch

• Likely the next device your frame will encounter is an Ethernet switch, also called a LAN switch

• This LAN switch forwards on your Ethernet frame intelligently on the basis of it’s Ethernet address

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A Typical Office Network

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The Router

• A router’s job is to take in IP packets and work out the next

best hop for that packet based on the router’s internal

routing tables

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IP Forwarding

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Layer 3 – Layer 2 Interaction

• Consider a router with Ethernet and ATM interfaces

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Destination Server

The final router knows

that the destination

IP device is directly

connected to it

The server will return

the requested files to

the source – the same

process in reverse

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Datacom Networking 7. Ethernet Concept

Chapter Objectives –Describe naming conventions used with Ethernet

–Describe the structure of a MAC address

–Describe the CSMA/CD principle

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LAN Technologies

• Ethernet

– By far the most widely used LAN technology today (95%+)

– Available in 10Mbps, 100Mbps and 1000Mbps flavours

• Token Ring

– Old IBM standard

– Workstations connected to rings, token passing concept

– Rings were available at speeds of 4Mbit/s and 16Mbit/s

• Fiber Distributed Data Interface (FDDI)

– LAN Fiber backbone technology, used 100Mbit/s ring

– No longer likely to be implemented in a new network

• Asynchronous Transfer Mode (ATM)

– Extensively deployed WAN technology, can be deployed in LANs

– However, Ethernet is a far more cost effective LAN technology

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Ethernet Evolution

Ethernet Design Goals

– Simplicity

– Efficient use of shared resources

– Ease of reconfiguration and

maintenance

– Compatibility

– Low cost

1972 1996

Gigabit standard (802.3z) VLANs

(802.1Q) 1000BaseT (802.3ab)

1980

EthernetV1 DIX - V2 in 82

1983 1990

10Base-T

(802.3i)

10BaseF (Fiber)

1993

802.3z study group formed to standardize

Gigabit Ethernet

1998 1985

IBM ships first

Token Ring LAN

IEEE

802.3

Standard

81-83

Fast

Ethernet

(802.3u)

1995 1997

Full

Duplex

(802.3x)

1973

Invention accredited to Robert Metcalfe-

Patent 1977

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IEEE 802 Family Architecture

IEEE 802.3 IEEE 802.4 IEEE 802.5 IEEE 802.6 Physical

IEEE 802.2

Internet

Transport

Upper

IEEE 802.x

Link

802.1 Internetworking

802.2 Logical Link Control (LLC)

802.3 CSMA\CD

802.4 Token Bus

802.5 Token Ring

802.6 Metropolitan Area

Networks

802.7 Broadband Tech Advisory Group

802.8 Fiber Optic Tech Advisory Group

802.9 Integrated Voice&Data Networks

802.10 Network Security

802.11 Wireless Networks

802.12 Demand Priority Access LAN's

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Ethernet Naming Conventions

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10BaseT Specifications

• 10BaseT

– 2 pairs of Cat 3 UTP

– By far the most widely used specification

• 10BaseF

– 2 strands of MMF

• 10Base2

– Thin coaxial or “Thinnet” (Dead)

• 10Base5

– Thick coaxial or “Thicknet” (Dead)

• 10Broad36

– Coaxial (Dead)

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MAC Address Format

7 0 - 7 0 - 7 0 - 7 0 - 7 0 - 7 0 -

octet order bit order

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Ethernet Principle – CSMA/CD

• CS = Carrier Sense

– Listen until no carrier is sensed, then transmit after a delay

• MA = Multiple Access

– Designed for a broadcast environment

– Every station hears every frame

• CD = Collision Detection

– Listen for a collision while you transmit

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Ethernet Operation – CSMA

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Ethernet Operation – CD

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Ethernet Collisions – More Detail

The adapters have to hear the collision while they

are still transmitting

They then transmit a 32-bit jam signal

They wait a random time before retransmission

If there are repeated collisions the adapter tries

again, up to a a maximum of 16 times

– Uses ―truncated binary exponential backoff‖ algorithm

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Ethernet, Logical vs Physical

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Datacom Networking 8. Ethernet Frame

Chapter Objectives –Identify the characteristics of the following Ethernet frame types:

•Ethernet Version 2

•IEEE 802.3 Novell Raw

•IEEE 802.3 Standard (with LLC)

•IEEE 802.3 SNAP

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Chapter Objectives

• After completing this chapter you will be able to:

– Identify the characteristics of the following Ethernet frame types:

• Ethernet Version 2

• IEEE 802.3 Novell Raw

• IEEE 802.3 Standard (with LLC)

• IEEE 802.3 SNAP

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Ethernet Version 2 Frame (DIX) Network

Data Link Control

Physical

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Examples of Ethernet Types

E-Type Value

NetWare 8137

XNS 0600, 0807

IP 0800

IP (VINES) 0BAD, 80C4

ARP 0806

RARP 8035

DRP 6003

LAT 6004

LAVC 6007

ARP (ATalk) 80F3

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IEEE 802.3 Frame - Novell ―RAW‖

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IEEE 802.3 Frame – with LLC (Standard Frame)

Network

Logical Link Control

Physical

Media Access Control

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IEEE 802.3 Frame – SNAP Network

SNAP

Physical

LLC

MAC

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Ethernet Frames Compared

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Determining Ethernet Frame Types

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Datacom Networking 9. Ethernet Device

Chapter Objectives –Describe collision domains and broadcast domains

–Describe how a hub, bridge and switch operate

–Identify where a crossover cable is used

–Describe the concept of Virtual LANs (VLANs)

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Chapter Objectives

• After completing this chapter you will:

– Describe collision domains and broadcast domains

– Describe how a hub, bridge and switch operate

– Identify where a crossover cable is used

– Describe the concept of Virtual LANs (VLANs)

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Broadcasts

Ethernet inherently supports broadcasts

Broadcast mechanism is used frequently

Example ARP – Address Resolution Protocol

A Broadcast Domain is all devices that will see a

broadcast frame

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Ethernet Devices

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Hubs

A hub is a simple OSI layer 1 device: a hub just

repeats the incoming signal

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Device-121

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Crossover Cables

A ―crossover‖ or ―crossed‖ cable may be used to

directly connect two Ethernet devices

– Transmit/Receive reversed at one end

– Crossover cables can be made or bought

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Connecting Hubs

Hubs may be connected or ―cascaded‖

– Connected hubs behave like one ―big‖ hub

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Transparent Bridging

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Bridges and Switches

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Device-128

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Device-129

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LAN Switch Operation

• Flooding

• Learning

• Forwarding

• Filtering

• User filtering

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LAN Switch Operation

• Having learned about destination addresses on the network the switch will forward frames intelligently on the basis of their MAC address

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Full-Duplex Ethernet

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Device-136

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Virtual LANs (VLANs)

• A VLAN is a logical grouping of nodes (clients and servers) residing in a common broadcast domain

• The broadcast domain has been artificially created within a LAN switch

– standard 802.3ac

LAN Switch

OFF

ON

OFF

ON

VLAN #1 - 5 workstations or repeaters

VLAN #2 - 11 workstations or repeaters

VLAN #3 - 6 workstations or repeaters

VLAN #4 - 10 workstations or repeaters

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VLAN Example -1

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VLAN Example -2

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Device-141

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Device-142

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Device-143

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Datacom Networking 10. Fast Ethernet

Chapter Objectives –Identify the physical specifications for Fast Ethernet

–Define auto-negotiation

–Understand how to interwork 10Mbit/s Ethernet and Fast Ethernet

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Fast Ethernet Essentials

• 10BaseT and 100BaseT

– Both use CSMA/CD

– Frame formats and frame lengths the same

– Usually deployed over Category 5 UTP

– Interconnections made with hubs, switches, routers etc.

– Standard defined by IEEE 802.3u

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Fast Ethernet vs 10BaseT Ethernet

• 10BaseT vs 100BaseT

– Transmits 10 times as much data in the same time

– New physical standards

– Interframe gap .96 microseconds instead of 9.6 microseconds (unchanged at 96 bit times)

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100BaseT Specifications

• 100BaseTX

– 2 pairs of Cat 5 UTP or Cat 1 STP

– By far the most widely used specification (95%+)

• 100BaseFX

– 2 strands of SMF or MMF

• 100BaseT4

– 4 pairs of Cat 3/4/5 UTP

• 100BaseT2

– 2 pairs of Cat 3/4/5 UTP

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Matching Interfaces

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Auto-Negotiation

10 or 100?

Full or half?

Then,

AUTO-NEGOTIATE!

Useful if unsure what

you‘re plugging in to

- AND when

upgrading to a

100BASE-T hub

??

Switch or

Hub

Algorithm used to negotiate common data service

Common RJ-45 connector for 1 of 8 services

Fast link pulses (FLP) similar to link integrity (LI)

Hub/NIC adjust speed to highest common mode

Order:

1. 1000BaseT FDX

2. 100BaseT2 FDX

3. 100BaseT2 HDX

4. 100BaseTX FDX

5. 100BaseT4

6. 100BaseTX

7. 10BaseT FDX

8. 10BaseT

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Flow Control

HDX - Switch generates collision

FDX - Switch generates pause

frame

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Ethernet-151

Datacom Networking 11. Gigabit Ethernet

Chapter Objectives –Identify the physical specifications for Gigabit Ethernet

–Describe carrier extend

–Describe frame bursting

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Gigabit Ethernet Essentials

• Latest extension to Ethernet

• 1000 Mbit/s - 10 times faster than fast Ethernet

• Compatible with existing Ethernet

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Gigabit Carrier Extend

P DA SA L/T Data F SS DS LLC Carrier Extend 448 bytes

64 previous minimum

+ 448 carrier extend

= 512 minimum frame size

Minimum frame size = 512 bytes

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Frame Bursting

• Frame Bursting is a means to reduce the Inefficiency of Carrier Extension

• The first frame is transmitted using the normal procedures for gigabit Ethernet.

• A frame burst timer is started to allow transmissions of up to 64 Kbits.

• If additional frames are queued for transmission and the 64 Kbit timer has not expired, two things happen

– The first frame is followed by carrier extend

– The next frame is transmitted

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Ethernet-155

Gigabit Ethernet Specifications

• 1000BaseLX

– 2 strands of SMF or MMF

• 1000BaseSX

– 2 strands of SMF

• 1000BaseCX

– 2 pairs of twinax

• 1000BaseT

– 4 pairs of Cat 5 UTP

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Ethernet-156

Ethernet Comparison

512 Bytes

64 Bytes

64 Bytes Min Frame

Size

1518 Bytes 1518 Bytes 1518 Bytes Max Frame

Size

16 tries 16 tries 16 tries Attempt

Limit

96 bit times 96 bit times 96 bit times Inter Frame

Gap

Fast Ethernet

802.3u

Ethernet,

802.3

Parameter Gigabit

Ethernet,

802.3z

48 bits 48 bits 48 bits Address

Size

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Datacom Networking 13. WAN Concepts

Chapter Objectives –Define circuit switching and packet switching

–Define SVCs and PVCs

–Identify HDLC protocols and describe where they are used

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Circuit Switching and Packet Switching

• Circuit Switching

– In a circuit switched network, a dedicated communications path is established between two terminals through the nodes of the network and for information transfer

• Packet Switching

– In this case it is not necessary to dedicate transmission capacity along a path through the network. Rather, data is sent out in a sequence of small chunks, called packets. Each packet is passed through the network from node to node along some path leading from the source to the destination.

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A B

A B

A B

A B

A B

A B

A B

Circuit Switching Packet Switching

Info

Info

Info

Info

CS vs. PS for different applications

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Leased Line and Dial-up

• Leased line

– With a leased line connection, a data user has a permanent dedicated transmission path which can be end to end across the network, locally, nationally or internationally.

• Dial-up

– This method is used for modem to modem data communication over the public switched telephone network (PSTN). Source and destination must have compatible modems.

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Virtual Circuits, PVC and SVC

• Virtual Circuit

– Appears to be a separate physical circuit to the user, but in fact is part of a shared pool of resources

• Permanent Virtual Circuit (PVC)

– PVC is a continuously dedicated virtual circuit

• Switched Virtual Circuit (SVC)

– SVC is a temporary virtual circuit established and maintained only for the duration of a data transfer session

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Datalink Layer Review

• A data link layer protocol only provides services on a point-to-point,

physical link.

• It’s up to a higher layer protocol to provide end-to-end services.

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HDLC, Derivatives and Variations

Used by Frame Relay

technology LAPF

Error-correcting modems

(specified as part of V.42) LAPM

ISDN D channel and Frame

Relay LAPD

Current X.25 implementations LAPB

Early X.25 implementations LAP

Uses HDLC Subset

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Datacom Networking 14. ATM

Chapter Objectives –Understand the concept of ATM

–Describe how an ATM switch works

–Describe where ATM is used in a Network

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ATM Essentials

• Flexible bearer technology (2Mbit/s – 2.5Gbit/s)

• Connection-orientated

• Uses fixed-size cells

• Able to guarantee Quality of Service (QoS)

• A multiservice technology: both voice and data traffic can be carried on an ATM network

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ATM connections

• In ATM a connection must be set up from source to destination before traffic can flow

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The ATM Cell

• Fixed cell size

• ATM switches read the cell header only, any information in the payload flows through the network transparently

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channel

1

channel

5

channel

1

empty

cell

channel

1

channel

7

channel

1

channel

2

Cell

Labelled multiplexing

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Asynchronous? Transfer Mode

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The principle of ATM switching

ATM

payload A 2

payload B 7

payload B 14

payload A 18

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ATM Multiplexing

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Constant

bit rate

Data

bursts

Variable

bit rate

Segmentation Addressing Multiplexing

Cell buffers

Segmentation and Multiplexing of different Broadband Services

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ATM Connections

• Many ways of setting up the connections:

– Permanent Virtual Circuit (PVC)

– Switched Virtual Circuit (SVC)

• Many types of connections:

– Constant Bit Rate (CBR)

– Variable Bit Rate (VBR)

– Available Bit Rate (ABR)

– Unspecified Bit Rate (UBR)

• Virtual connections can be of any bandwidth

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ATM Connections

• Connections are virtual channels

– Permanent (PVC)

– Switched (SVC)

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ATM‘s Physical Layer

ATM Layer

Physical Layer

Adaptation Layer

PMD

TC

SAR

CS

Layer two

Layer one

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ATM Interface References Public

Networks

Private

Networks

Public

NNI

B-ICI

Public

NNI

Private

NNI

Public

UNI

Public

UNI

Private

UNI

Private

UNI

Public

UNI

Public

UNI

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The Physical Interfaces Supported

• E1 2.048 Mbit/s, T1 1.544 Mbit/s

• E3 34 Mbit/s, DS3 45 Mbit/s

• UTP-25 25 Mbit/s

• STS-1 51.84 Mbit/s

• TAXI 100 Mbit/s

• UTP- 5 I55.52 Mbit/s

• STM-1, OC3 155.52 Mbit/s

• STM-4, OC12 622.08 Mbit/s

• STM-16, OC48 2.488 Gbit/s

• STM-64, OC192 10 Gbit/s - work in progress

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SDH/SONET

• The base standard defined to support ATM is:

– European/world standard

• Synchronous Digital Hierarchy (SDH)

– American standard

• Synchronous Optical Network (SONET)

• The two systems are identical at transmission rates of 155 Mbps and above

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SONET / SDH Topology

Section

ADM

Line Path

ADM ADM

Repeaters

Inserted Data

Dropped Data

Repeaters

Inserted Data

Dropped Data

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Physical Implementation of SDH

• Physical aspects of SDH/SONET

– Fibre

• single mode

– Preferred connection to operator connection

• multimode

– Used for private ATM networks, for example, a university campus

– UTP

• Category 5

– Used among workgroups

– To replace traditional LANs with ATM

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ATM Layer

ATM Layer

Physical Layer

Adaptation Layer

PMD

TC

SAR

CS

Layer two

Layer one

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ATM Cell Format

VPI (high order)

VCI - 1 VPI (low order)

VCI - 2

VCI - 3 Payload type CLP

Header error control

Payload (48 octets)

bit order

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UNI Cell Header

48-octet data field

GFC VPI

VPI VCI

VCI

VCI PTI

HEC

8 1

1st Octet

2nd Octet

3rd Octet

4th Octet

5th Octet

Bits

CLP

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NNI Cell Header

48-octet data field

VPI

VPI VCI

VCI

VCI PTI CLP

HEC

8 1

1st Octet

2nd Octet

3rd Octet

4th Octet

5th Octet

Bits

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Generic Flow Control

• Locally significant only (at UNI)

– Any value will be overwritten by the switch

• Two modes of operation:

– Controlled mode

– Uncontrolled mode

• Currently only uncontrolled mode is defined

– Uncontrolled GFC = 0000

48-octet data field

VPI

VPI VCI

VCI

VCI PTI CLP

HEC

GFC

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Virtual Path Identifier

• Identifies this cell’s path

• 8 bits available at the UNI

• 12 bits available at the NNI

– 256/4096 possible simultaneous paths

– Maximum number of usable bits is negotiable between user and network

48-octet data field

VCI

VCI

VCI PTI CLP

HEC

VPI

VPI

GFC

‘Real’ physical link

VPI 57

VPI 68

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Virtual Channel Identifier

• Identifies this cell’s channel

• 16 bits available at the UNI & NNI

– 65,536 possible simultaneous channels per path

– Maximum number of useable bits is negotiable on a per-path basis

VPI 57

VPI 68

VCI 39 VCI 40

VCI 38 VCI 39

VPI 68

VPI 68

VCI 39

VCI44

VCI 40 VCI 41

Physical Interfaces 4- octet data field

PTI CLP

HEC

VPI

VPI

GFC

VCI

VCI

VCI

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Virtual Paths

Multiple channels destined for a common location can be quickly and simply switched by the network if they share a common VPI

channels 131 145 117

channels 131 145 117

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Reserved Virtual Connections

• The following VPI/VCI combinations have been reserved:

– VPI = 0 VCI = 0 to 15 ITU-T

– VPI = 0 VCI = 16 to 31 ATM Forum

– VPI = ALL VCI = 1 to 5

• In practice, carriers regard VCIs 0 to 31 as reserved for all VPIs

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Payload Type Identifier

PTI Coding (MSB first)

Interpretation

User data cell, congestion not experienced, SDU type = 0 User data cell, congestion not experienced, SDU type = 1 User data cell, congestion experienced, SDU type = 0 User data cell, congestion experienced, SDU type = 1 Segment OAM F5 flow-related cell End-to-end OAM F5 flow-related cell Resource management cell Reserved for future functions

000

001

010

011

100

101

110

111

48-octet data field

VPI

VPI VCI

VCI

VCI CLP

HEC

GFC

PTI

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Congestion Control

• Bit 2 of the PTI may be used to indicate to the destination that

congestion has taken place in the network

• The bit is called Explicit Forward Congestion Indicator (EFCI)

• This will occur when switches are discarding cells with CLP =1

48-byte data field

VPI

VPI VCI

VCI

VCI CLP

HEC

GFC

PTI

EFCI

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Cell Loss Priority

• CLP operates independently on each active VPI/VCI

• A switch may flip CLP from 0 to 1, for example, if traffic on

a VPI/VCI exceeds the maximum agreed sustainable cell

rate

CLP = 0

CLP = 0 CLP = 1 CLP = 1

Private UNI Private NNI Public UNI Public NNI

48-octet data field

VPI

VPI VCI

VCI

VCI

HEC

GFC

PTI CLP

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Header Error Check

• The HEC is performed on the header only

– Supports forward correction of single-bit errors

– Supports detection of multiple-bit errors

• Faulty cells are discarded

– At the UNI:

• Error detection is mandatory

• Error correction is optional

• The HEC is generated/verified at the TC part of the physical layer

48-octet data field

VPI

VPI VCI

VCI

VCI CLP

GFC

PTI

HEC

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Virtual Paths and Channels ATM Switch

Virtual Channel Switch

Virtual Path Switch

VCI1 VCI2 VCI3 VCI4

VCI1

VCI2

VCI3

VCI4

VCIa

VCIb

VCIa

VCIb

VPI1

VPI2

VPI3

VPI1

VPI2

VPI4

VPI5

VPI5

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The Switch Map

ATM Cell ATM Cells

VPI/VCI = A/B VPI/VCI = X/Y

1 2

Switch Map (1) VPI VCI Interface VPI VCI

A B 2 X Y

- - - - -

VPI/VCI is of

LOCAL Significance

Only

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ATM Switching

• ATM cells are being switched along a predefined connection

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CommServ – Education Division Datacom Networking ATM-198

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CommServ – Education Division Datacom Networking ATM-199

The Adaptation Layer

ATM Layer

Physical Layer

Adaptation Layer

PMD

TC

SAR

CS

Layer two

Layer one

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QoS Service Catagories

• CBR Constant Bit Rate

• VBR-RT Variable Bit Rate - Real Time

• VBR-NRT Variable Bit Rate - Non-Real Time

• ABR Available Bit Rate

• UBR Unspecified Bit Rate

• GFR Guaranteed Frame Rate (later)

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ATM Service Classes

• Classes as defined by ITU-T rec. I 362

Class A Class B Class C Class D

Timing between

source and destination Required Not required

Bit rate Constant Variable

Connection mode Connection-oriented Connectionless

AAL 1 AAL 2 AAL 3 AAL 4

AAL 5

Relevant Adaptation Layer

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General Principles of Adaptation

Adaptation Layer

SAR

CS

Higher layer data

H H

The use of a CS is not required by all AALs Etc.

H T H T H T

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Usage of Adaptation Layer

• AAL is used to adapt a source application to ATM

– ATM switching takes place in the ATM Layer.

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AAL1 Segmentation and Reassembly sublayer

Protocol Data Unit (SAR PDU)

Payload, 47 bytes (376 bits) Header, 5 bytes

SNP SN

44

SN, Sequence Number, 3 bits are used

to detect loss of cells

SNP, Sequence Number Protection

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ATM Adaptation Layer type 1

Payload

Information for:

•Lost cell detection

•Synchronization

•Support of structured Circuit Emulation

1 octet47 octets

Real time, constant bit rate stream (e.g. PCM Speech)

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AAL 1

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CommServ – Education Division Datacom Networking ATM-207

AAL 2

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CommServ – Education Division Datacom Networking ATM-208

AAL 2

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CommServ – Education Division Datacom Networking ATM-209

AAL2 Segmentation And Reassemble sublayer

Protocol Data Unit (SAR PDU)

Header, 5 bytes

LI CID

8

CID, Channel Identity

LI, Length Indicator

UUI, User-to-user Indicator

HEC, Header Error Control

PayloadPayloadPayload

UUIHEC

8

STF

655

STF, Start Field

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CommServ – Education Division Datacom Networking ATM-210

AAL2 demultiplexed to AAL2U

Header, 5 bytesPayloadPayloadPayload

Payload

Payload

Payload

AAL2

AAL 2U

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AAL5 (SEAL)

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CommServ – Education Division Datacom Networking ATM-212

AAL5, variable bit rate

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CommServ – Education Division Datacom Networking ATM-213

AAL5 Trailer

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CommServ – Education Division Datacom Networking ATM-214

AAL5 Transmission

• AAL5 makes use of the PTI field in ATM cell header

– Bit 1 = 1 indicates this cell carries the AAL5 trailer

48-byte data field

VPI

VPI VCI

VCI

VCI CLP

HEC

GFC

PTI

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The use of AALs

ATM

AAL1ATM

AAL5

PCM (voice)

IP (64KB max.)

48 octet

ATM SDUs 53 octet

ATM PDUs

AAL1ATM

AAL5

AAL

ATM ATM ATM

AAL

ATM

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ATM Applications – Large Core Networks

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CommServ – Education Division Datacom Networking ATM-217

Site 2

Site 1

Transport Layer

Network Control Layer

Signaling

User Plane

RNC

TDM

Network

PCM

64 kbps

AMR coding

12 kbps

WCDMA Transport

• Aggregation of server nodes in the Control Layer

TSC

Server

MSC

Server Q.BICC

N-ISUP RANAP

Iu

MGW

GCP GCP

TRA

• M-MGw build the Transport Layer

AAL2

Switch

AAL2

Switches

Q.AAL2

Q.AAL2

• Bandwidth efficient transport using “Codec at the edge” • Local Switching

TDM

Network

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CommServ – Education Division Datacom Networking ATM-218

ATM Based Signaling

MAP-ATM

TCAP

MAP/CAP

SCCP

MTP3b

SSCF-NNI

ATM

L1

AAL5

SSCOP

SGSN <---> HLR

3G MSC <--> HLR

HLR <--> VLR

MSC <--> MSC

RANAP-ATM

RANAP

SCCP

MTP3b

SSCF-NNI

ATM

L1

AAL5

SSCOP

MSC MA <--> RNC

MSC server <--> RNC

SGSN <---> RNC

Q.AAL2-ATM

Q.AAL2

MTP3b

SSCF-NNI

ATM

L1

AAL5

SSCOP

GCP-ATM

GCP

MTP3b

SSCF-NNI

ATM

L1

AAL5

SSCOP

MSC server <---> MGW

BICC/ISUP-ATM

BICC/ISUP

MTP3b

SSCF-NNI

ATM

L1

AAL5

SSCOP

MSC server <---> MSC server

TSC server <--> PSTN

MSC MA <---> RNC

C-MGw <--> RNC

C-MGw <--> C-MGw

RNC <--> RNC

RNSAP-ATM

RNSAP

SCCP

MTP3b

SSCF-NNI

ATM

L1

AAL5

SSCOP

RNC <---> RNC

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219

Datacom Networking 15. Frame Relay

Chapter Objectives –Understand the concept of Frame Relay

–Describe how a Frame Relay switch works

–Describe where Frame Relay is used in a Network

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220

Frame Relay Essentials

• WAN packet switching technology, preceded ATM

• Typically implemented at speeds from 56kbit/s to 2Mbit/s (Can go to speeds of 45Mbit/s)

• Supports PVCs (SVCs are supported, but generally not used)

• Uses variable-length frames to transfer data

• Has some built in traffic control mechanisms

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221

Frame (LAPF) Format

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222

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CommServ – Education Division Datacom Networking

Frame Relay Terms

DLCI 21

DLCI 23

DLCI 22

DLCI 31

DLCI 32

DLCI 33

S 0

Frame Relay

Switch

Token Ring

SDLC FRAD

Definitions

DLCI: Data Link Connection Identifier

CIR : Committed Information Rate

Bc : Committed burst in bits

Be : Excess burst in bits

FECN: Forward Explicit Congestion Notify

BECN: Backward Explicit Congestion Notify

DE: Discard Eligible

Router

Frame Relay Switch

Maps DLCIs to form a PVC

Controls each PVC‘s CIR, Bc, Be Congestion Notification: FECN, BECN

Provides Accounting and Monitoring

Router

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224

Frame Relay Switching

• Frame Relay Frames are being switched along a predefined connection

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225

Congestion Control

• FECN – Forward Explicit Congestion Notification

• BECN – Backward Explicit Congestion Notification

• DE – Discard Eligibility

8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1

Byte 1 Byte 2

DLCI(msb) DLCI(lsb) C/R EA EA DE

F

E

C

N

B

E

C

N

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226

Congestion Notification

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227

Network Congestion Recovery

Committed Information Rate (CIR)

Maximum Information

Rate

Guaranteed transmission

Transmit if possible DE =

1

Discard all excess

Page 228: EduDivision-DATACOM NETWORKING

CommServ – Education Division Datacom Networking

Frame Relay Illustration

• Committed Information Rate (CIR)

• Port speed (PIR)

• Permanent Virtual Circuits (PVCs)

Free if

Available

Traffic

Time

Peak

CIR What

You Pay

for {

{

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CommServ – Education Division Datacom Networking Frame Relay-

229

Performance Model

Frame 1

DE=0

Frame 2

DE=0

Frame 3

DE=0

Frame 1

DE=0

Frame 2

DE=0

Frame 3

DE=0

Frame 4

DE=1

Frame 1

DE=0

Frame 2

DE=0

Frame 3

DE=1

Frame 4

DISCARDED

Time Time Time

Number of

bits

transmitte

d

Number of

bits

transmitte

d

Number of

bits

transmitte

d

Discard region

DE = 1 region

DE = 0 region

Discard region

DE = 1 region

DE = 0 region

Discard region

DE = 1 region

DE = 0 region

Bc+Be

Bc

Bc+Be

Bc

Bc+Be

Bc

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230

FR Applications – Corporate LAN Interconnect

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CommServ – Education Division Datacom Networking Frame Relay-

231

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CommServ – Education Division Datacom Networking

interface s 0 encapsulation frame-relay ! interface s 0.1 point-to-point ip address 172.16.1.1 255.255.255.0 frame-relay interface-dlci 42 ! interface s 0.2 point-to-point ip address 172.16.4.1 255.255.255.0 frame-relay interface-dlci 53 ! Interface s 0.3 point-to-point ip address 172.16.2.10 255.255.255.0 frame-relay interface-dlci 59

interface s 0 encapsulation frame-relay ! interface s 0.1 point-to-point ip address 172.16.2.18 255.255.255.0 frame-relay interface-dlci 36 ! interface s 0.2 point-to-point ip address 172.16.3.25 frame-relay interface-dlci 46

Frame Relay Configuration Example

DLCI 36

Frame Relay

Network 172.16.3.0

B A

DLCI 42

172.16.1.0 DLCI 59

172.16.2.0

DLCI 53 172.16.4.0

DLCI 46

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CommServ – Education Division Datacom Networking

interface s 0 encapsulation frame-relay ! interface s 0.1 multipoint ip address 172.16.1.1 255.255.255.0 frame-relay interface-dlci 300 frame-relay interface-dlci 212 frame-relay interface-dlci 437

interface s 0 encapsulation frame-relay ! interface s 0.1 point-to-point ip address 172.16.1.18 255.255.255.0 frame-relay interface-dlci 36

Frame Relay

B A

172.16.1.2

172.16.1.3

D

C

DLCI 36

Frame Relay Multipoint Example

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234

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CommServ – Education Division Datacom Networking X25-235

Datacom Networking 16. X25

Chapter Objectives •Understand the concept X.25

•Describe the structure of a LAPB frame

•Describe the structure of an X.25 packet

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CommServ – Education Division Datacom Networking X25-236

X.25 Essentials

Old WAN packet switching technology, preceded both

Frame Relay and ATM

Designed to run over error-prone physical links so

contains extensive error checking mechanisms

X.25 typically implemented over low speed links <64K

- (low speed by today‘s standards)

X.25 used extensively with older proprietary systems

- banking terminals, control links for telephone exchanges

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CommServ – Education Division Datacom Networking X25-237

X.25 and OSI Reference Model

Application

Presentation

Session

Transport

Network

Data Link

Physical Physical

Frame

Packet X.25 Protocol

Suite

Upper

Layer

Protocols

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CommServ – Education Division Datacom Networking X25-238

X.25 Interface

User

Process

Packet

Link

Access

Link

Access

Physical Physical

User

Process

Packet

Multi-channel

Logical Interface

LAPB Link Level

Logical Interface

Physical Interface Physical

DLC

Network

OSI-RM User Data

User Data Layer 3

Header

X.25 Packet

LAPB

Header

Layer 3

Header User Data FCS

LAPB Frame

10101110111......

Node-A Node-B

Flag

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CommServ – Education Division Datacom Networking X25-239

X.25 WAN

DTE DCE DCE

Packet Switching Network

Leased line

Physical DTE

Physical DCE

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X.25 WAN (contd)

DTE

Packet Switching Network

X 25 context is between

DTE and Packet switched network (DCE)

DTE

DTE

X 25

X 25

Logical DCE

at layer 2 / 3

Logical DTE

at layer 2 / 3

DCE DCE

Transparent at layer 2 / 3

Logical DTE

at layer 2 / 3

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CommServ – Education Division Datacom Networking

Flag Address Information FCS Flag Control

0 1 1 1 1 1 1 0 0 1 1 1 1 1 1 0

Flag

Flags

Page 242: EduDivision-DATACOM NETWORKING

CommServ – Education Division Datacom Networking

Flag Address Information FCS Flag Control

0 N(R) N(S) I:

7 6 5 4 3 2 1 0

F P

S: N(R) 0 1

7 6 5 4 3 2 1 0

U: P F X X 1 1

7 6 5 4 3 2 1 0

P F

X X X

X X

01 or 03

Address and Control

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CommServ – Education Division Datacom Networking X25-243

Information frames

I Information nr p ns 0

Supervisory frames

RR Receiver Ready nr p/f 0 0 0 1

RNR Receiver Not Ready nr p/f 0 1 0 1

REJ Reject nr p/f 1 0 0 1

Unnumbered frames

SABM Set asynchronous balanced mode 0 0 1 p 1 1 1 1

UA Unnumbered acknowledgement 0 1 1 f 0 0 1 1

DISC Disconnect 0 1 0 p 0 0 1 1

DM Disconnected mode 0 0 0 f 1 1 1 1

FRMR Frame Reject 1 0 0 f 0 1 1 1

LAPB Commands and Responses

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CommServ – Education Division Datacom Networking X25-244

LAPB Operation 1

SABM

SABM

UA UA

Info nr=0 ns=0

Info nr=0 ns=0

Info nr=1 ns=0

Info nr=1 ns=2

Info nr=1 ns=1

Info nr=1 ns=0

Info nr=1 ns=1

Info nr=1 ns=3 Info nr=1 ns=2

Info nr=1 ns=3

RR nr=4 RR nr=4

Info nr=4 ns=1 Info nr=4 ns=1

DCE

DTE

Info nr=2 ns=4 Info nr=2 ns=4

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LAPB Operation 2

Info nr=2 ns=7

Info nr=2 ns=7

REJ nr=6

DCE

DTE

Info nr=2 ns=5

Info nr=2 ns=4

Info nr=2 ns=6 Info nr=2 ns=5

Info nr=2 ns=4

Ignored as

CRC incorrect

Info nr=2 ns=0

Info nr=2 ns=0

REJ nr=6

Info nr=2 ns=6

Info nr=2 ns=6 Info nr=2 ns=7

Info nr=2 ns=0

Info nr=2 ns=0

Info nr=2 ns=7

Info nr=1 ns=2

Info nr=1 ns=2

REJ frame

acknowledges

up to frame 5

XX

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CommServ – Education Division Datacom Networking X25-246

LAPB Operation 3

Info nr=2 ns=7 p=0

Info nr=2 ns=7 p=0

DCE DTE

Info nr=2 ns=5 p=0

Info nr=2 ns=4 p=0

Info nr=2 ns=6 p=0 Info nr=2 ns=5 p=0

Info nr=2 ns=4 p=0

Info nr=2 ns=4 p=1

Info nr=2 ns=4 p=1

T1

timer

T1

timer

Info nr=2 ns=4 p=1

Info nr=2 ns=4 p=1

Info nr=2 ns=4 p=1

Info nr=2 ns=6 p=0

T1

timer

N 2 times Info nr=2 ns=4 p=1

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CommServ – Education Division Datacom Networking

Logical Channel Numbers (LCNs)

LCN LCN

LCN LCN

Logical DTE

Logical DCE

Logical DTE Logical DTE

Logical DCE

Logical DTE

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CommServ – Education Division Datacom Networking

LCNs (contd)

LCN 5 LCN 8

LCN 45

LCN 19

LCN 9 LCN 9

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CommServ – Education Division Datacom Networking

General Format Identifier

Q D

01 Modulo 8 10 Modulo 128 11 Extensions 00 Reserved

8 7 6 5 4 3 2 1 Bits

Byte 1 LCGN Modulo

GFI normal

L D

Long Address indicator Call Request packets only

8 7 6 5 4 3 2 1 Bits

Byte 1 LCGN Modulo

GFI Extended addressing

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CommServ – Education Division Datacom Networking

Byte 1

2

3

1 2 3 4 5 6 7 8

Logical Channel Number

GFI

Bits

Packet Type Identifier

Logical Channel Group Number

Packet Layer Header

16 Logical Channel Group Numbers

256 Logical Channel Numbers in each group

A Logical channel may be identified by LCN or by LCGN + LCN

Logical channel 0 = LCGN 0 , LCN 0

Logical channel 1025 = LCGN 4 , LCN 1

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CommServ – Education Division Datacom Networking

Packet Header

Call request / incoming call 0 0 0 0 1 0 1 1

Call accept / call connected 0 0 0 0 1 1 1 1

Clear request / Clear indication 0 0 0 1 0 0 1 1

Clear confirmation 0 0 0 1 0 1 1 1

Data pr m ps 0

RR pr 0 0 0 0 1

RNR pr 0 0 1 0 1

REJ pr 0 1 0 0 1

Interrupt 0 0 1 0 0 0 1 1

Interrupt confirmation 0 0 1 0 0 1 1 1

Reset request / Reset indication 0 0 0 1 1 0 1 1

Reset confirmation 0 0 0 1 1 1 1 1

Restart request/restart indication 1 1 1 1 1 0 1 1

Restart confirmation 1 1 1 1 1 1 1 1

Diagnostic 1 1 1 1 0 0 0 1

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Call Setup

Call request Incoming Call

Call Accept Call connected

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General Format Identifier Logical Channel Group Number

Logical Channel Number

Packet Type Identifier

Calling DTE Address Length Called DTE Address Length

Called DTE Address Field BCD - 2 digits / octet Variable length (15 digits max)

Facility Field Length

1 2 3 4 5 6 7 8 Bits

Call Request, Incoming call, Call Accepted, Call Connected

Facility Field codes and values Variable length

Calling DTE Address Field BCD - 2 digits / octet Variable length (15 digits max)

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X.25 Operation

DTE A DTE B A Initiates a

virtual call to B

Incoming Call

Call Accepted

Data pr=0 ps=0

Data pr=0 ps=1

Data pr=2 ps=0

RR pr = 1

Call Request

Call Connected

Data pr=0 ps=0

Data pr=0 ps=1

Data pr=3 ps=0

Network

RR pr=1

RR pr=2

Data pr=1 ps=3

Data pr=1 ps=2

Data pr=1 ps=3

Data pr=1 ps=2

Acknowledgement

from local DCE

Acknowledgement

from local node

Call established

Data transfer stage

Acknowledgement

changed by local

node for packet

with ps=2

Packet delayed at local node

until ACK has been received

from remote DTE

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X.121 Addressing

DNIC Data Network Identification Code (DCC + NI)

DCC Data Country Code (3 digits)

NI Network Identifier (1 digit)

NTN Network Terminal Number (max10 digits incl SA)

SA Sub-address

234 2 19201005

234 2 19201004 74

240 2 00451

272 4 30000200

310 6 000715

DNIC NI NTN SA

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Datacom Networking 17. PPP

Chapter Objectives –Describe how a PPP frame structure

–Describe the function of the Link Control Protocol (LCP)

–Describe the function of the Network Control Protocol (NCP)

–Describe where PPP is used in a Network

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PPP Essentials

• Very widely-used standard for transporting layer 3 datagrams (especially IP) over point-to-point links (rfc 1661)

• PPP replaces the older Serial Line Interface Protocol (SLIP)

• PPP is comprised of: – Encapsulation method

– Link Control Protocol (LCP)

– Network Control Protocol (NCP)

• Often referred to as “self-configuring”

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PPP Frame Format

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Link Control Protocol (LCP) Functions

• Determine encapsulation format options

• Negotiate optimal packet size

• Terminate the link

• Authenticate the identity of the peer on the link [ PAP or CHAP ]

(optional)

• Negotiate PPP Multilink data compression (optional)

• Link quality monitoring (optional)

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Network Control Protocols (NCPs)

• NCPs are a series of independently-defined protocols that

encapsulate network layer protocols

• Examples: TCP/IP, DECnet, AppleTalk, IPX…

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PPP Logical Flow

LCP

Link DEAD

Start

Up State

NCP Negotiate Options

Bind NCP

Last

Last

Terminate Data Exchange

Fail authentication

Open LCP phase

NCP phase

Open State

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PPP Applications

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Datacom Networking 18. Modems

Chapter Objectives –Describe the function of a modem

–Identify modem standards and associated speeds

–Describe where modems are used in a Network

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Chapter Objectives

• After completing this chapter you will be able to:

– Describe the function of a modem

– Identify modem standards and associated speeds

– Describe where modems are used in a Network

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Modem – MOdulation and DEModulation

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Modem Standards Rec. Speed (bit/s) Transmission

ModePSTN LL

2WLL4W

Back-upvia PSTN

Mod.Method

V.21 300 Asynchronous (A) FD FD FSK

V.23 1200/600 A and S HD HD FD * FSK

V.22 1200/600 A and S FD FD * DPSK

V.22bis

V.22f.bk

2400/1200 A and S FD FD * QAM

V.26bis 2400/1200 Synchronous (S) HD HD FD * DPSK

V.26ter 2400/1200 A and S FD FD * DPSK

V.27ter

V.26bisf.bk

4800/2400 S HD HD FD * DPSK

V.29 9600/7200/4800 A and S FD QAM

V.32 9600/4800 A and S FD FD * QAM/TCM

V.33 14400/12000 S FD QAM/TCM

V.34 28800 S FD TCM

V.34bis 28800/31200/33600 S FD TCM

Baseband 2400/1800/1200

7200/4800/3600

19200/14400/9600

A and S HD FD

V.90 56000 to the end user33600 from the end user

S Asymetric PCM

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LAPM Frame Format

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Modem Applications

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Datacom Networking 19. ISDN

Chapter Objectives –Describe the concept of ISDN

–Identify the reference points in an ISDN network

–Identify the differences between primary and basic rate ISDN

–Describe where ISDN is used in network

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ISDN Essentials

• Full services, digital, end-to-end network

• Narrowband ISDN and Broadband ISDN (B-ISDN is ATM-based)

• ISDN based on 64Kbit/s channels

• Two channel types: Bearer (B) Channel and Data (D) Channel

– B channel for user traffic, uses PPP

– D channel signalling and control, uses LAPD

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ISDN BRI Reference Model

TE1

NT2 NT1

Terminal Adapter

U

Interface

T

Interface

S

Interface

R

Interface

To Telco

To Telco TE2

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PRI Frame Format for E1/T1

7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 0

B1 D-Channel B31 Framing

7 6 5 4 3 2 1

256 bits/125 microseconds (2.048Mbps)

E1

Signaling

+31 +0 +1 +16

Data Data

F

7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0

B1 B2 B23 D-Channel

24th Channel

193 bits/125 microseconds (1.544Mbps)

T1

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Basic Rate Interface (BRI)

B1

B2

D

64Kbs

64Kbs

16Kbs

2B + 1D

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Primary Rate Interface (PRI)

64Kbs

64Kbs

: :

B1 64Kbs

64Kbs

64Kbs

: B2

D

23B + 1D (USA)

30B + 1D (EISDN)

B22 or

29 B23 or

30

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LAPD Format

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Types of ISDN Connections

• Circuit Switched

• Packet Switched

• Frame Mode

• Semi-permanent

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ISDN Applications

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Datacom Networking 20. xDSL

Chapter Objectives –Describe the concept of xDSL

–Identify the speeds of common xDSL standards

–Describe where xDSL is used in a network

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Copper Access

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xDSL Technologies

• Asymmetric Digital Subscriber Line (ADSL)

• Rate Adaptive Digital Subscriber Line (RADSL)

• High-bit-rate Digital Subscriber Line (HDSL)

• Symmetrical Digital Subscriber Line (SDSL)

• Very-high-data-rate Digital Subscriber Line (VDSL)

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DSL Types

Technology Data Rate Mode Distance (ft) Distance (m)

ISDL/ISDN 128Kbps

Duplex 18000 5400

HDSL 2.048Mbps

1.544Mbps

Duplex

Duplex

12000 3600

SDSL 2.048Mbps

1.544Mbps

Duplex

Duplex

10000 3000

ADSL 6.144Mbps

640Kbps

Downstream

Upstream

12000 3600

RADSL 0.32-9Mbps Downstream Depends on data

rate

VDSL 12.96Mbps

25.92Mbps

51.84Mbps

1.5 – 6Mbps

Downstream

Upstream

4500

3000

1000

1350

900

300

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ADSL standards and bandwidth

8,1 / 1,5 Mbps

Annex A (POTS)

8,1 / 1,8 Mbps Annex B (ISDN)

8 / 3.4 Mbps ‗Annex J‘ (POTS)

Scenario ...

ADSL ADSL2 ADSL2+ ADSL2++

VDSL1/2 DMT

13,4 / 1,6 Mbps Annex A (POTS)

11,5 / 1,9 Mbps Annex B (ISDN)

5,7 / 1,0 Mbps Annex L (POTS)

11,5 / 3,5 Mbps

Annex M (POTS)

28,7 / 1,6 Mbps Annex A (POTS)

26,8 / 1,9 Mbps Annex B (ISDN)

26,8 / 3,5 Mbps

Annex M (POTS)

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ITU G.992.1 - ADSL

• ITU G.992.1 (ADSL) is implemented from EDA 1.1

• The following ADSL annexes are available:

ISDN DS ADSL

Annex B f

[kHz]

ADSL

Annex A f

[kHz]

DS

PO

TS

US

US

Variable frequency spectrum

PO

TS

f

[kHz]

DS ADSL

Annex M US

25 80 138 276 1104 552

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ITU G.992.3 - ADSL2

• ITU G.992.3 (ADSL2) is implemented from EDA 1.3

• The following ADSL2 annexes are available:

ISDN DS ADSL2

Annex B f

[kHz]

ADSL2

Annex A f

[kHz]

DS

PO

TS

US

US

Variable frequency spectrum

PO

TS

f

[kHz]

DS ADSL2

Annex M US

25 80 138 276 1104

DS

PO

TS

US

552

f

[kHz]

ADSL2

Annex L

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ITU G.992.5 - ADSL2+

• ITU G.992.5 (ADSL2+) is implemented from EDA 2.0

• New frequency spectrum compared with G992.1 & G992.3

• The following ADSL2+ annexes are available:

ISDN DS ADSL2+

Annex B f

[kHz] PO

TS

f

[kHz]

ADSL2+

Annex A f

[kHz]

DS

DS

PO

TS

US

ADSL2+

Annex M US

25 80 138 276 2208

US

Variable frequency spectrum

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ADSL2/ADSL2+ Facts

• ADSL2 Boosts performance

– 13 Mbps / 3 Mbps (DS/US)

• ADSL2 provides service over longer loop lengths

– Approx. 500 m more compared with G992.1

– Annex L even more on long loop lengths

• ADSL2+ Boosts performance even more

– 28 Mbps / 3 Mbps (DS/US)

• ADSL2+ relevant for loop lengths up to 2 km

Length, Km 1 Km 2 Km 3 Km 4 Km 5 Km 6 Km

8

13

ADSL2

ADSL2+

28

Data Rate, Mbps

Annex L is

relevant here

7 Km

ADSL

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xDSL Applications

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Multiple downstream

tunnels with same content

Video service via PPP tunnels

Channel 1

Channel 2

Set-top Box

Channel 1

Set-top Box

Channel 2

Set-top Box

Channel 2

Router/

BRAS

Video

Service

Provider

IP

DSLAM

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Video service via IGMP

Supports

IGMP snooping

Supports

IP Multicast

Only one downstream

for each channel

Channel 1

Channel 2

Set-top Box

Channel 1

Set-top Box

Channel 2

Set-top Box

Channel 2

Router/

BRAS

Video

Service

Provider

IP

DSLAM

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Datacom Networking 21. SDH & SONET

Chapter Objectives –Describe the differences between PDH and SDH/SONET

–Identify the speeds associated with SDH/SONET

–Describe where SDH/SONET is used in a Network

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PDH Systems

DS0 @ 64k

1.5Mb 6Mb 45Mb 274Mb X 4 X 7 X 6

2Mb 8Mb 34Mb 565Mb 140Mb

X 3

0

X 4 X 4 X 4

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PDH Multiplexing and Demultiplexing

• With PDH everything must be de-multiplexed to extract a single signal!

– Motivation for development of SDH/SONET

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PDH/SDH and SONET

SDH/SONET

– Higher bandwidth, easier to manage, backwards-

compatible with PDH

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SONET and SDH Frames

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SONET and SDH Frames – Overhead

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Overhead Layers

ADM

or

DCS REG REG PTE PTE

Section Section Section Section

Line Line

Path

Path

Termination

Section

Termination Line

Termination

Section

Termination Path

Termination

Service (DS1, DS3 ..)

Mapping and

Demapping

Service

Mapping and

Demapping

PTE Path Terminating Element

REG Regenerator

ADM Add-Drop Multiplexer

DCS Digital Cross-Connect System

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SDH Multiplexing Structure

Pointer

SOH

SOH

STM-1

VC-4

C-4

260

9

P

O

H

140 Mbit/s C-4 VC-4 STM-1

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SDH Multiplexing Structure

x 1

x 3

x 1

x 7

x 3

x 1 x N

STM-N

AUG AU4 VC4 C4

C3

C2

C12

C11

139,264

kbit /s

44,736 34,368

kbit /s

6,312

kbit /s

2,048

kbit /s

1,544

kbit /s

VC3

VC2

VC12

VC11

TU3

TU2

TU12

TUG2

TUG3

Aligning

Mapping

Multiplexing STM Synchronous Transport Mode

AUG Administrative Unit Group

AU Administrative Unit

TUG Tributary Unit Group

TU Tributary Unit VC Virtual Container

C Container

AU3 VC3

x 3

x 7

TU11 TU11

x 4

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SDH/SONET Equipment

• Add-drop multiplexer

– A multiplexer capable or extracting or inserting lower rate signals from a higher rate multiplexed signal without completely demultiplexing the signal

• Digital Cross Connect

– An electronic cross-connect which has access to lower-rate channels in higher-rate multiplexed signals and can cross-connect those channels

• Regenerator (Repeater)

– Device that restores a degraded digital signal for continued transmission

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SDH / SONET Acronyms

This Graphic is the Property

of Quill Training Services

9953.280

2488.320

622.080

155.520

51.840

STS-192

STS-48

STS-12

STS-3

STS-1

OC-192

OC-48

OC-12

OC-3

OC-1

STM-64

STM-16

STM-4

STM-1

SDH-64

SDH-16

SDH-4

SDH-1

Format Frame

Level SDH

( Mbps ) Line Rate

Format Frame

Carrier Level Optical

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Applications of SDH/SONET

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Datacom Networking 22. POS

Chapter Objectives –Describe the concept of Packet Over SONET (POS)

–Describe where POS is used in a Network

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Packet Over SONET (POS) Essentials

• POS = Packet over SONET or Packet over SDH

• A standard for transmitting packets (primarily IP) over high speed SONET/SDH links

• Consists of PPP over SONET or SDH

– IP is carried within PPP

• Works with all speed of SONET/SDH

• Attractive solution for large ISP cores

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IP over PPP over SDH/SONET

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CommServ – Education Division Datacom Networking POS-316

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POS Applications – Large Core ISP Networks

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CommServ – Education Division Datacom Networking POS-318

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Datacom Networking 23. MPLS

Chapter Objectives –Describe the concept of Multiprotocol Label Switching (MPLS)

–Describe how MPLS devices work

–Identify how MPLS is implemented with different technologies

–Describe where MPLS is used in a Network

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Multiprotocol Label Switching Essentials

• MPLS is an Internet Engineering Task Force (IETF) forwarding standard

• Concept:

– Packets entering the network are analysed and put into a forward equivalence class (FEC)

– Forward equivalence classes are mapped to connections through the network

– The packet is labelled according to which path it should take through the network

– Packet is transferred though the network by switching on the label

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MPLS Network Components

Label Switching Router (LSR) deployed in

the core of the network to perform high

speed label switching

Label Edge Router (LER) deployed at the

edge of the network for connectivity to user

networks. Also called ingress and egress

LSRs.

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MPLS in Operation

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MPLS in Operation

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LER Functions

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LSR Functions

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MPLS Implementation

• MPLS can be implemented as:

• A Layer 3 (or “Pure IP”) solution

– The Label is extra information attached to the IP header

– LERs are edge routers running MPLS software

– LSRs are core routers running MPLS software

• An ATM solution

– The Label is the VPI/VCI

– LERs are edge routers running MPLS software

– LSRs are ATM switches running MPLS software

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MPLS Label in a ―Pure IP‖ Solution

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MPLS Label in an IP over ATM Solution

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MPLS Applications – Large Backbone

Networks

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Architecture-

352

Datacom Networking 25. Internet Architecture

Chapter Objectives

–Describe the structure of the TCP/IP protocol suite

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Architecture-

353

Internet Protocols

TCP

IP

Transport Layer

RARP

UDP OSPF EGP

BGP

ICMP IGMP

RIP

TELNET, FTP, TFTP, BOOTP, SMTP, HTTP, SNMP, NFS, NTP, , ,

Internet Layer ARP

Type Code

Protocol Number

Port Number

IEEE 802.2, PPP, LAPB, Ethernet, RS232, 802.3, 802.5,

Upper Layer

Link/Physical Layer

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Upper-Layer Protocols: End User and Utility

Functions

TCP

IP

Transport Layer

RARP

UDP OSPF EGP

BGP

ICMP IGMP

RIP

TELNET, FTP, TFTP, HTTP, SMTP

SNMP, BOOTP/DHCP, DNS, NTP, RADIUS

Internet Layer

ARP

Type Code

Protocol Number

Port Number

IEEE 802.2, PPP, LAPB, Ethernet, RS232, 802.3, 802.5,

Upper Layer

Link/Physical Layer

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Transport Layer Protocols

TCP

IP

Transport Layer

RARP

UDP OSPF EGP

BGP

ICMP IGMP

RIP

SNMP, BOOTP/DHCP, DNS, NTP, RADIUS, , , ,

Internet Layer

ARP

Type Code

Protocol Number

Port Number

IEEE 802.2, PPP, LAPB, Ethernet, RS232, 802.3, 802.5,

Upper Layer

Link/Physical Layer

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Internet Layer Protocol: Internet Protocol

TCP

IP

Transport Layer

RARP

UDP OSPF EGP

BGP

ICMP IGMP

RIP

SNMP, BOOTP/DHCP, DNS, NTP, RADIUS, , , ,

Internet Layer

ARP

Type Code

Protocol Number

Port Number

IEEE 802.2, PPP, LAPB, Ethernet, RS232, 802.3, 802.5,

Upper Layer

Link/Physical Layer

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Anomalies

TCP

IP

Transport Layer

RARP

UDP OSPF EGP

BGP

ICMP IGMP

RIP

SNMP, BOOTP/DHCP, DNS, NTP, RADIUS, , , ,

Internet Layer ARP

Type Code

Protocol Number

Port Number

IEEE 802.2, PPP, LAPB, Ethernet, RS232, 802.3, 802.5,

Upper Layer

Link/Physical Layer

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Sending and Receiving a Message

Application specify:

Upper Layer Protocol Internet address

Upper Layer protocol:

Build header for peer to describe format Specify Port number to select Application

Transport Layer protocol:

Build Header for peer to describe format Specify Protocol number to select proper

Internet Layer (IP):

Build header for peer to describe format Source and destination IP addresses

Link Layer (unique for physical connection):

Build header for peer to describe format Identify IP stack with Type Code number

at IP address

Transport Layer protocol

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Internet Society (ISOC) Specifications

• All Internet standards specified by the IETF, a division of ISOC

• Standards are called Request for Comments (RFCs) and are sequentially numbered

• All standards available free from http://www.ietf.org

• RFC search facility available at http://www.rfc-editor.org/

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Datacom Networking 26. Internet Applications

Chapter Objectives –Describe how the Hypertext Transfer Protocol (HTTP) works

–Describe how the Domain Name Service (DNS) works

–Describe how the Simple Network Management Protocol (SNMP) works

–Describe how the File Transfer Protocol (FTP) works

–Describe how Telnet works

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Hypertext Transfer Protocol

Architecture

HTTP

TCP

IP

Protocol 6

HTTP

TCP

IP

Protocol 6

Server Client

Port 80 Port 80

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HTTP Operation

Web client

browser TCP port 80

hypertext

links

Web

server

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Uniform Resource Locator (URL)

scheme = http://, ftp://, telnet://,

news:, mailto: , , , , ,

http://server.name/file.type

scheme

path=domain name

or IP address

search object

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Domain Name Service (DNS)

root unnamed

int org net mil gov edu com uk au us

geographically based domains:

2-letter country codes

defined in ISO 3166

organizationally based domains:

defined by Internet Registry (IR)

IP

Physical network

DNS

UDP

Protocol 17

port 53

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File Transfer Protocol

IP

Physical network

FTP

TCP

Protocol 6

port 21

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Telnet

IP

Physical network

Telnet

TCP

Protocol 6

port 23

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Simple Network Management Protocol

Architecture

SNMP

UDP

IP

Protocol 17

SNMP

UDP

IP

Protocol 17

Manager Agent

Port 169 Port 169

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SNMP Management

Manager

Managed

Resources

Managed Node

Agent

MIB

SNMP

SNMP Operations

Set, Get, GetResponse,

GetNext, Trap

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Datacom Networking 27. Transport Layer Protocol

Chapter Objectives –Describe how connection may be multiplexed

–Define ports and sockets

–Describe the differences between TCP and UDP

–Describe the operation of TCP and UDP

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Multiplexing Connections

Internet

client server

SMTP

FTP

HTTP

SMTP

FTP

HTTP

IP address

X

IP address

Y

destination

port 25 source

port 3000

destination

port 21 source

port 3001

destination

port 80 source

port 3002

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Connection Components

Internet

client server

SMTP

FTP

HTTP

SMTP

FTP

HTTP

IP address

X

IP address

Y

destination

port 25 source

port 3000

destination

port 21 source

port 3001

destination

port 80 source

port 3002

socket socket

connection

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Transport Layer Protocols

UDP

IP

TCP

Upper Layer Protocols

Physical network

ports

6 17 protocols

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Transmission Control Protocol (TCP)

Segment Format

TCP Data

+0

+4

bit order

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

octet +0 octet +1 octet +2 octet +3

octet order

+8

+16

+20

source port destination port

sequence number

acknowledgement number

check sum urgent pointer

options (if any) padding

window +12 hdr

length reserved code

bits

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Transmission Control Protocol (TCP)

Segment Format

TCP Data

+0

+4

bit order

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

octet +0 octet +1 octet +2 octet +3

octet order

+8

+12

+16

+20

source port destination port

sequence number

acknowledgement number

hdr length window reserved

code bits

check sum urgent pointer

options (if any) padding

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Connection Sequence

0

Sender Receiver

SYN,seq=x

SYN/ACK,seq=y,ack=x+1

Internet

ACK, seq=x+1,ack=y+1

(SYN,seq=x)

(SYN,seq=y,ack=x+1)

(ACK, seq=x+1,ack=y+1) DATA,seq=x+1,ack=y+1

(DATA,seq=x+1,ack=y+1)

1

2

3

4

Legend:

CLOSED

LISTEN

SYN-SENT

ESTABLISHED

(received and sent)

SYN-RECEIVED

4

0

1 3

2

4

Note: ACK does not

use sequence space

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Closing Sequence

FIN,seq=x,ack=y

ACK,seq=y, ack=x+1

ACK, seq=x+1,ack=y+1

(ACK, seq=y,ack=x+1)

(ACK, seq=x+1,ack=y+1)

FIN/ACK,seq=y ack=x+1

(FIN/ACK, seq=y,ack=x+1)

Inform Application ->

(CLOSE ->)

(<- CLOSE)

(FIN,seq=x,ack=y)

Wait=2*MSL

ESTABLISHED

FIN-WAIT-1

FIN-WAIT-2

CLOSE-WAIT

LAST-ACK

TIME-WAIT CLOSED

Internet Sender Receiver

4 4

5

7

6

9

10

0 0

0 10

9

7 4

5

6

Legend:

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User Datagram Protocol (UDP)

bit order

UDP Data

UDP Destination Port

UDP Checksum UDP Message Length

UDP Source Port

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

octet +0 octet +1 octet +2 octet +3

+0

+4

Octet order

Segment Format

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Datacom Networking 28. Internet Protocol

Chapter Objectives –Describe IP functions and characteristics

–Describe the fields contained within an IP header

–Describe the Internet Control Message Protocol (ICMP)

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Internet Protocol

IP Data

+0

+4

bit order

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

octet +0 octet +1 octet +2 octet +3

octet order

datagram format

+8

+12

+16

+20

ver total length

time to live

source IP address

options (if any) padding

hdr ver length

identification flags fragment offset

header checksum protocol

destination IP address

+24

type of service

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Internet Protocol

IP Data

+0

+4

bit order

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

octet +0 octet +1 octet +2 octet +3

octet order

+8

+12

+16

+20

ver total length

time to live

source IP address

options (if any) padding

hdr ver length type of service

identification flags fragment offset

header checksum protocol

destination IP address

+24

datagram format

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Internet Protocol

IP Data

+0

+4

bit order

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

octet +0 octet +1 octet +2 octet +3

octet order

datagram format

+8

+12

+16

+20

ver total length

time to live

source IP address

options (if any) padding

hdr ver length type of service

identification flags fragment offset

header checksum protocol

destination IP address

+24

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Internet Protocol

datagram format

0 IP Data

+0

+4

bit order

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

octet +0 octet +1 octet +2 octet +3

octet order

+8

+12

+16

+20

ver total length

time to live

source IP address

options (if any) padding

hdr ver length type of service

identification flags fragment offset

header checksum protocol

destination IP address

+24

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Internet Control Message Protocol

UDP

IP

TCP

Upper Layer Protocols

Physical network

ports

6 17 protocols

ICMP

1 Utility (no ports)

Ping

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Ping Command

Usage: ping [-t] [-a] [-n count] [-l size] [-f] [-i TTL] [-v TOS]

[-r count] [-s count] [[-j host-list] | [-k host-list]]

[-w timeout] destination-list

Options:

-t Ping the specified host until interrupted.

-a Resolve addresses to hostnames.

-n count Number of echo requests to send.

-l size Send buffer size.

-f Set Don't Fragment flag in packet.

-i TTL Time To Live.

-v TOS Type Of Service.

-r count Record route for count hops.

-s count Timestamp for count hops.

-j host-list Loose source route along host-list.

-k host-list Strict source route along host-list.

-w timeout Timeout in milliseconds to wait for reply.

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Datacom Networking 29. IP Addressing

Chapter Objectives –Describe the structure of an IP address

–Identify different address classes

–Describe the function of a subnet mask

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IP Address Function

Router 1 Router 2

Router 3

A B

C D

E

G

H

K J

M L

Host 1

Host 2

Host 3

N

P

F

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IP Address Format

Class A

Class B

Class C

Class D

bit order

Host Network

octet order

0

Host 1

Host 1

Multicast Address

Network 0

Network 1 0

1 1 0 1

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

octet +0 octet +1 octet +2 octet +3

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IP Address Notation

binary format

bit order octet order

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

octet +0 octet +1 octet +2 octet +3

0-255 0-255 0-255 0-255

0-255 0-255 0-255 0-255

128 129 64 192

dotted decimal format

dotted decimal example

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IP Addresses in Decimal

Class Valid Network Numbers

A 1 through 126

B 128.1 through 191.254

C 192.0.1 through 223.255.254

D 224.0.0.1 through 239.255.255.255

E 240 through 255.255.255.255

Valid Host Numbers

Not applicable

1 through 255.255.254

1 through 255.254

1 through 254

Reserved

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Class B Subnet Mask

user’s

IP address 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1

Subnet 1

Mask 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0

bit order octet order

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

octet +0 octet +1 octet +2 octet +3

Host Class B

1 Network 0 format

Network Subnet Host

Subnet 1

IP address 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0

1 0

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Multicast Addressing

• Class D addresses are Multicast addresses

• Range 224.0.0.1 through 239.255.255.255 is available

Class D IP multicast address 1 1 0 1

7 0 - 7 0 - 7 0 - 7 0 - IP

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IP Addressing Problem

Over 4 billion address space

ABC Ltd.

London, England

129.1.0.0

RST Co.

New York, U.S.

129.2.0.0

MNO Ltd.

London, England

170.1.0.0

JKL Co.

New York, U.S.

170.2.0.0

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CIDR Addressing

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 1 1 0 0 0 0 0

subnet supernet

host Class C network

mask

In dotted decimal notation, supernet mask = 255.255.248.0 In CIDR notation, supernet mask = /21

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Datacom Networking 30. Internet Routing

Chapter Objectives –Describe the concept of IP routing

–Identify the information contained within a typical routing table

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IP Forwarder Architecture

Physical

Link

Internet

Physical

Link

Internet

IP Routing

Source

router

Intermediate

router

Destination

router

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Sample IP Route Table (RT)

Destination Route Mask Next Hop Port Metric Type Source Age

0.0.0.0 0.0.0.0 129.192.64.28 J4.1 0 DIR Static 0

129.192.16.0 255.255.0.0 129.192.16.3 J3 2 REM RIP 19477560

129.192.17.0 255.255.0.0 129.192.16.6 J4.2 3 REM OSPF 1422605

129.192.18.0 255.255.0.0 129.192.18.3 J3 2 REM BGP 4933

129.192.64.0 255.255.0.0 129.192.40.3 J4.3 2 REM BGP 4933

172.20.1.3 255.255.255.255 129.192.40.3 J4.3 2 DIR LOC 1949913

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Routing Table

One Forwarding Table

198.113.181.0 [170/304793] 192.150.42.177 02:03:50 D

198.113.178.0

192.168.96.0

192.168.97.0

[110/9936] 192.150.42.177 02:03:50 O

192.150.42.177 00:00:20 R

C

[120/3]

Ethernet0

Ethernet0

Ethernet0

Ethernet0

Age Source Network # Interface Next Hop Metric

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Default Gateway

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Routing-419

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Routing-421

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Selection Criteria

r X

s Y

t Z

1

2

n

Hops Address J

Route

Table

J1

J2

Jn

?

?

?

m X

n Y

0 Z

1

2

3

Hops J

Route Table

J1

J2

J3

Z

Address

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Simplified Routing Example

J1

J2 J3

J1 J1

J1 J2

J1

J2 J3

J1 J1

11.0.0.1

12.0.0.1

12.0.0.2

11.0.0.2

10.0.0.1 14.0.0.1

10.0.0.3 10.0.0.2

13.0.0.1

13.0.0.3 13.0.0.2

14.0.0.2

A

C

B D

E F G

0 0.0.0.0 1

Hops Address J

0 10.0.0.3 1

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Simplified Routing Example

J1

J2 J3

J1 J1

J1 J2

J1

J2 J3

J1 J1

11.0.0.1

12.0.0.1

12.0.0.2

11.0.0.2

10.0.0.1 14.0.0.1

10.0.0.3 10.0.0.2

13.0.0.1

13.0.0.3 13.0.0.2

14.0.0.2

A

C

B D

E F G

0 10.0.0.2

0 10.0.0.3

1 13.0.0.2

1 13.0.0.3

2 13.0.0.2

2 13.0.0.3

3

3

2

2

1

1

Address J

Route

Table

1 10.0.0.2

1 10.0.0.3

1 13.0.0.2

1 13.0.0.3

1

1

2

2

Hops Address J

0 0.0.0.0 1

Hops Address J

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Simplified Routing Example

J1

J2 J3

J1 J1

J1 J2

J1

J2 J3

J1 J1

11.0.0.1

12.0.0.1

12.0.0.2

11.0.0.2

10.0.0.1 14.0.0.1

10.0.0.3 10.0.0.2

13.0.0.1

13.0.0.3 13.0.0.2

14.0.0.2

A

C

B D

E F G

0 10.0.0.2

0 10.0.0.3

1 13.0.0.2

1 13.0.0.3

2 13.0.0.2

2 13.0.0.3

3

3

2

2

1

1

Address J

Route

Table

1 10.0.0.2

1 10.0.0.3

1 13.0.0.2

1 13.0.0.3

1

1

2

2

Hops Address J

0 0.0.0.0 1

Hops Address J

0 13.0.0.2

0 13.0.0.3

1 10.0.0.2

1 10.0.0.3

2 10.0.0.2

2 10.0.0.3

3

3

2

2

1

1

Hops Address J

Route

Table

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Datacom Networking 31. Dynamic Routing

Chapter Objectives –Describe routing protocol categories

–Briefly describe the following routing protocols:

•Routing Information Protocol (RIP)

•Open Shortest Path First (OSPF)

•Border Gateway Protocol (BGP)

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Dynamic Routing Categories

Dynamic Routing

Interior Exterior

Vector Distance (RIP)

Link State (OSPF)

BGP EGP

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Scope of Dynamic Routing Protocols

area-1

area-2

area-3

area-0

OSPF

area-0

OSPF

Internet

RIP

BGP

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RIP Architecture

RIP

UDP

IP

Port 520

Protocol 17

RIP

UDP

IP

Port 520

Protocol 17

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RIP Operation

LAN or WAN neighbors

route table

route table

update update update

update update

30 seconds

(minimum)

180 seconds

(maximum)

120 seconds

(delay)

>180, set inactive

purge from RT

update

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RIP—Distance Vector

Send Routing Table to Neighbors

Net A

Net B Net C

Net D

E0 S0 S0 S1 S0 E0

R1 R2 R3

A E0

B S0

B

C

S0

S1

C

D

S0

E0

A S0 B S0

A S0 D S1 S0 D

S0 C

Network Interface Network Interface Network Interface

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• Update = 1x 30 sec

• Invalid = 3x 90 sec

• Holddown = 3x 90 sec

• Flush = 7x 210 sec

RIP Timers

Net A

Net B Net C

Net D

E0 S0 S0 S1 S0 E0

R1 R2 R3

A E0

B S0

B

C

S0

S1

C

D

S0

E0

A S0 B S0

A S0 D S1 S0 D

S0 C

Network Interface Network Interface Network Interface

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RIP Metric

R1

R2

R3

T1

56k

T1

0 Hops

1 Hop

Path A

Path B

Hops

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Count to Infinity

• Hop count max = 15

• 16 = infinity

Net A

Net B Net C

Net D

E0 S0 S0 S1 S0 E0

R1 R2 R3

X

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Count to Infinity

A = 4 Hop

A = 5 Hop

A = 6 Hop

A = 7 Hop

Net A

Net B Net C

Net D

E0 S0 S0 S1 S0 E0

R1 R2 R3

X

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Split Horizon

Do not send routing

updates back in the

direction from

which it came

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OSPF Architecture

OSPF

IP

Protocol 9

OSPF

IP

Protocol 9

Link and Physical Layers

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OSPF

• Dynamic routing protocol

• Link state or SPF technology

• Developed by OSPF working group of IETF (RFC 1253)

• Intra-autonomous system (IGP)

• Designed expressly for TCP/IP Internet environment

• Fast convergence

• Variable-length subnet masks

• Discontiguous subnets

• No periodic updates

• Route authentication

• Delivered two years after IGRP

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Link State Routing

• Neighbor discovery

• Constructing an LSP

• Distribute LSP

• Compute routes

• On network failure

– New LSPs flooded

– All routers recompute routing tables

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OSPF Link State Database

LSD

LSD LSD

LSD

identical

interface

Metric = 100,000,000/link bit rate

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Topology/Link State Database

• A router has a separate LS database for each area to which it belongs

• All routers belonging to the same area have identical database

• SPF calculation is performed separately for each area

• LSA flooding is bounded by area

• Router ID determined by interface or command

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OSPF Metric

• Derived from bandwidth

–100 ÷ bandwidth

– 56-kbps serial link = 1785 64-kbps serial link = 1562

– T1 (1.544-Mbps serial link) = 65 E1 (2.048-Mbps serial link) = 48

– 4-Mbps Token Ring = 25 16-Mbps Token Ring = 6

– Ethernet = 10 Fast Ethernet / FDDI = 1

• Configured via

–Interface sub-command: bandwidth

–Interface sub-command: ip ospf cost

–Router sub-command:

–ospf auto-cost reference-bandwidth

–Default = 108

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Simplified Routing Example

1.544 Mbps

Route

Table

J1

J2 J3

J1 J1

J1 J2

J1

J2 J3

J1 J1

10.0.0.11

11.0.0.2

12.0.0.11

11.0.0.1

10.0.0.1 10.0.0.12

10.0.0.3 10.0.0.2

12.0.0.1

12.0.0.3 12.0.0.2

12.0.0.12

65 10.0.0.2

65 10.0.0.3

65 12.0.0.2

65 12.0.0.3

1

1

2

2

Metric Address J

0 12.0.0.2

0 12.0.0.3

3125 10.0.0.2

3125 10.0.0.3

130 10.0.0.2

130 10.0.0.3

3

3

2

2

1

1

Metric Address J

Route

Table

0 0.0.0.0 1

Hops Address J

A

C

B D

E F G

1.544 Mbps

64 Kbps

0 10.0.0.2

0 10.0.0.3

3125 12.0.0.2

3125 12.0.0.3

130 12.0.0.2

130 12.0.0.3

3

3

2

2

1

1

Metric Address J

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BGP Architecture

BGP

TCP

IP

Port 179

Protocol 6

BGP

TCP

IP

Port 179

Protocol 6

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Routing Information Bases (RIBs)

BGP speaker

to/from other BGP speakers

I-RIB

L-RIB

O-RIB

received

sent

used

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BGP Basics

• Runs over TCP

• Path vector protocol

• Incremental update

AS 100 AS 101

AS 102

A

Peering

D

E

B

C

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BGP General Operation

• Learns multiple paths via internal and external BGP speakers

• Picks the best path and installs in the IP forwarding table

• Policies applied by influencing the best path selection

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Internal BGP Peering

• BGP peer within the same AS

• Not required to be directly connected

• IBGP neighbors should be fully meshed

• Few BGP speakers in corporate network

AS 100

A

E

D

B

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External BGP Peering

C

A

• Between BGP speakers in different AS

• Should be directly connected

B

AS 100 AS 101

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• Representative of most BGP configurations

BGP Configuration Example

15.1.1.0 15.0.0.0 19.0.0.0

15.1.1.1 15.1.1.2

Configuration for A Configuration for B

A B AS 100 AS 200

router bgp 100

network 19.0.0.0

neighbor 15.1.1.2 remote-as 200

router bgp 200

network 15.0.0.0

neighbor 15.1.1.1 remote-as 100

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Route Aggregation

1.544 Mbps

Route

Table

J1

J2 J3

J1 J1

J1 J2

J1

J2 J3

J1 J1

11.0.0.1

12.0.0.1

12.0.0.2

11.0.0.2

10.0.0.1 14.0.0.1

10.0.0.3 10.0.0.2

13.0.0.1

13.0.0.3 13.0.0.2

14.0.0.2

0 0.0.0.0 1

Hops Address J

A

C

B D

E F G

1.544 Mbps

64 Kbps

0 13.0.0.0

1560 10.0.0.0

1300 10.0.0.0

3

2

1

Metric Address J

Route

Table

0 10.0.0.0

1560 13.0.0.0

1300 13.0.0.0

3

2

1

Metric Address J

650 10.0.0.0

650 13.0.0.0

1

2

Metric Address J

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