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Prof. Sang-Jo Yoo

Grading

Attendance : 20% H/W: 20% Term-project: 30% Final exam: 30%

Prof. Sang-Jo Yoo sjyoo@inha.ac.kr 860-8304(5 남 369)

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Prof. Sang-Jo Yoo

Text Books

Data & Computer Communications, Sixth Edition, William Stallings, Prentice Hall

Computer Networks, Third Edition, Andrew S. Tanenbaum, Prentice Hall

IPng and the TCP/IP Protocols: implementing the next generation internet, Stephen A. Thomas, Wiley

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Prof. Sang-Jo Yoo

Term-Project

Project proposal: March 26th

Project presentation and demo: May 28th

Socket programming (Winsock) Java network programming

Chatting, file transfer, etc..

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Prof. Sang-Jo Yoo

1. Introduction

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Prof. Sang-Jo Yoo

Contents

1. Communication Model

2. Data Communication Networking

3. Protocols & Protocols Architecture

4. Standards Organizations

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Prof. Sang-Jo Yoo

Computer Networking

Networking today Connectivity from ..,

Office, factory, class room, labs, libraries, stores, bank, …

Connectivity regardless of time and place Wired links Wireless links

Exploding use of the Internet Benefits Also, challenges

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Prof. Sang-Jo Yoo

Computer Networking

What is a computer network A collection of computers and peripherals connected so that

Resource sharing is enables User/computer communication is enhanced And much more …

The key components are Hosts Switches/routers Links Enabling software

A network may also be a connected collection of smaller networks

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Prof. Sang-Jo Yoo

Source Transmitter

Source System

TransmissionSystem

Receiver Destination

Destination System

Workstation

Modem Modem

ServerPSTN : Public Switched Telephone Network

1. Communication Model

Simplified Communication Model

Network Terminal Adapter

NetworkTerminal Adapter

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Prof. Sang-Jo Yoo

Data Communication Tasks

Transmission system utilizationInterfacingSignal generationSynchronizationExchange managementError detection/correctionFlow controlAddressingRoutingRecoveryMessage formattingSecurityNetwork management

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Prof. Sang-Jo Yoo

Transmission System Utilization

- To make efficient use of transmission facilities that are typically shared among the number of communicating devices- Various techniques, for example multiplexer, are used to allocate the total capacity of a transmission medium among a number of users- Congestion control techniques may be required

X.25 PAD

Packet SwitchAsync Terminal

RS-232C

X.25

PAD : Packet Assembly & DisassemblyDTE : Data Terminal Equipment

B-NT

ATM Switch B-TEB-TE

155 M

B-NT : BISDN Network TerminatorB-TE : BISDN Terminal Equipment

X.25 DTE

B-TERing or Star

X.25

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Prof. Sang-Jo Yoo

Interface

- A device must interface with transmission system in order to communicate with the other devices

ISDN Switch TETE

NT

PSTN Switch PSTN Switch

Digital

ModemDTE

Analog Analog

ISDN Switch

NTDigitalDigital Digital

TE

Analog

Digital Digital

S-interfaceU-interface

Terminator

Analog telephone

Analog telephone

PSTN

ISDN

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Prof. Sang-Jo Yoo

Signal generation

- capable of being propagated through the transmission system- interpretable as data at the receiver

PSTN Switch PSTN Switch

Digital AnalogAnalog

Analog Signal(0-3.4kHz)

Analog Signal(0-3.4kHz)

ISDN Switch

NT

ISDN Switch

Digital Digital

TE

Digital

S-interface -> Digital Waveform(192Kbps = 2B+D+overhead)

U-interface

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Prof. Sang-Jo Yoo

Synchronization

- Especially , in case of digital communication, receiver must be able to determine when a signal begins to arrive and when it ends - It must know the duration of each signal element

Analog Network

Digital Network

1

0

duration

Sender

1

0

duration

Receiver

Noise + Distortion + Original SignalOriginal SignalPropagation

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Prof. Sang-Jo Yoo

Exchange management

- Requirement for communication between two party that might be collected- For example, Analog Phone : push button for dialing, ringing for alerting, lifting handset ISDN Phone : Setup Msg, Alerting Msg, Connect Msg, etc

PSTNOutgoing Telephone Incoming Telephone

ready tone for dialLifting handset

DTMF Dial-Tone

Address Decoding&Determine Destination Ringing

ConnectConnect (Stop Alerting Tone)Lifting handset

Alerting Tone

Conversation

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Prof. Sang-Jo Yoo

Error detection/correction

- Required in circumstances where errors cannot be tolerated- Channel coding scheme using overhead bit- Retransmission using protocol (ARQ: Automatic Retransmission Request)

MS BS

CDMA Wireless Network

MS : Mobile StationBS : Base Station

PSTNSwitch

PSTN Subscriber

Error detection/correction

Data Send(Convolution Code)

ARQ

Real Time Data

Retransmission Non-realtime Data

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Prof. Sang-Jo Yoo

Flow control- Required to assure that source does not overwhelm the destination by sending data transfer that they can be processed and absorbed- In case of User-to Network Interface , flow control function is performed in data link layer- In case of User-to-User Interface , transport layer has flow control function

INFO

RR

RNR

TE TEUNI

UUI

USER NETWORK

RR : Receive ReadyRNR : Receive Not Ready no available buffer

INFO

Enough buffer

TR_INFO_PDU

TR_RNR_PDU no available buffer

USER

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Prof. Sang-Jo Yoo

Addressing & Routing

- Indicate the identify of the intended destination when a transmission facility is shared by more than two devices

B-TE

B-TE

B-TE

RSN

E.164 Address(02-2616100-03)

E.164 Address(02-2636100-01)

E.164 Address(042-8695430)

ATM-MSS

ATM Switch

RSN

RSN

RSN

HSNNNI

IISP

UNI

RSN : Remote Switching NodeHSN : Header Switching NodeIISP : Interim Inter-Switch ProtocolNNI : Network-Network InterfaceUNI : User-to-Network Interface

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Prof. Sang-Jo Yoo

Recovery

- Needed in situations in which an information exchange is interrupted due to a fault somewhere in the system- The Objectivity is either to be able to resume activity at the point of interruption or at least to restore the state of the systems involved to the condition prior to the beginning of the exchange- Generally, Recovery function is applied in transmission facility such as Switch, Fiber Loop Carrier, SDH system via path duplication, equipment duplication

Transmission Path Duplication

SDH System

SDH System

SDH System

SDH System

Fault occured

F.O

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Prof. Sang-Jo Yoo

Message formatting

Security

- An agreement between two parties as to the form of the data to be exchanged or transmitted- For example, both sides must use the same binary or ASCII code format for character

- In sender side, only intended party actually receive the data- In receiver side, received data have not been altered in transit and data have actually come from the purported sender

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Prof. Sang-Jo Yoo

Network management

- Configure the system - Monitor its status - React to failures and overloads- Plan intelligently for future growth

Private Network Public Network

SNMP CMIP

UDP IP

OSI 7 Protocol

Target System (Switch, etc)

Physical Layer

NMS

Manager Client

AgentServer

LAN

SNMP : Simple Network Management ProtocolCMIP : Common Management Interface Protocol NMS : Network Management System

SNMP UDP IPMAC

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Prof. Sang-Jo Yoo

2. Data Communication Networking

Wide-Area Networks

Local -Area Network

- Cover a large geographical area, require the crossing of public right of ways- Typically, consists of a number of interconnected switching nodes- Don’t care the content of the data - Two main technologies : circuit switching, packet switching- PSTN, PSPDN, Frame Relay &Switching, ISDN, BISDN

- The Scope of LAN is small, typically a single building or cluster of building => lead to different technical solution- LAN is owned by same organization that owns the attached devices => user care about network management & substantial capital investment- The internal data rates of LANs are typically much greater that those of wide are networks - Ethernet(802.3), ATM LAN, Wireless LAN(802.11)

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Prof. Sang-Jo Yoo

Source Transmitter

Source System

TransmissionSystem

Receiver Destination

Destination System

Local Area Network

Switching Node

Wide Area Network

TE TE TE

TE TE

Simplified Network Model

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Prof. Sang-Jo Yoo

3. Protocols and Protocols Architecture

Protocols: A set of rules governing the exchange of data between two or more (peer) entities. The key elements of a protocol are syntax, semantics(procedures), and timing

Key Elements of Protocol Syntax - format, size, and contents of protocol messages or

packets Procedures - semantics of messages, actions to take in response

to reception of different messages Timing - speed matching etc., when to discard a message,

retransmit, give up, etc. Protocol Layering

Layering is a popular way of structuring such a family of network protocols

Each layer represents a new level of abstraction with well defined function

Interfaces - primitive objects, operations, and services provided by one layer to its higher layers.

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Prof. Sang-Jo Yoo

record

DSAP

DHost

Application

Transport

Network Access

Application

Transport

Network Access

Transport PDU

Packet PDU

record

DSAP

DHost

Application Data

Transport Protocol Data Unit

Network ProtocolData Unit (packet)

Transport Header

Network Header

Protocol Data Units

Operation of a Protocol Architecture Source X Destination Y

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Prof. Sang-Jo Yoo

TCP/IP Protocol Architecture

- used in the grandparent of all computer networks, the ARPANET, and its successor, the Internet

• Application layer (TELNET,RLOGIN, FTP, SMTP, ...)• Host-to-host, or transport layer (TCP, UDP)• Internet layer (IP)• Network access layer• Physical layer

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Prof. Sang-Jo Yoo

Source Transmitter

Source System

TransmissionSystem

Receiver Destination

Destination System

Application

TCP/UDP

IP

Physical

ARP

Application

TCP/UDP

IP

Physical

ARPLAN 1

LAN 2

LAN 3

ARP : Address Resolution ProtocolRemote routerLocal Router

TCP/IP Protocol Architecture Model

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Prof. Sang-Jo Yoo

ISO OSI 7 Layer ModelApplicationPresentation

Provides independence to the application processes from differences in data representation (syntax)

Session Establishes, manages, and terminates connections (sessions) between application processesTransport

Provides reliable, transparent transfer of data between end points; provides end-to-end (host-to-host) error recovery and flow control

NetworkProvides upper layers with independence from the data transmission and switching technologies used (routing, congestion control)

Data LinkProvides for the reliable transfer of information across the physical link; sends blocks of data (frames) with necessary synchronization, error control, and flow control

PhysicalConcerned with transmission of unstructured bit stream over physical medium; deals with the mechanical, electrical, functional, and procedural characteristics to access the physical medium (voltages, pin assignments, bit times, ..)

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Prof. Sang-Jo Yoo

Correspondence between TCP/IP and OSI architecture

TCP/IP OSI

Application

Transport(host-to-host)

Internet

Network Access

Physical

Application

Presentation

Session

Transport

Network

Data Link

Physical

Hardware

Firmware

Software

User Space

Operating System

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Prof. Sang-Jo Yoo

4. Standards Organizations

IETF IRTF

IAB(Internet Architecture Board)

Internet Engineering Task Force

RFCs

The Internet and Internet Standards

Internet Research Task Force

Final Decision

Requests for Comments

Internet Engineering Task Force (IETF)

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Prof. Sang-Jo Yoo

Standards Track Diagram

Enter Experiment

ProposedStandard

DraftStandard

Standard

Historial

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Prof. Sang-Jo Yoo

International Organization for Standardization(ISO)

ISO

- international agency for the development of standards on a wide range of subjects- voluntary, nontreaty organization

IEC

JTC1

International Electrotechnical Commission

OSI communication architecture &the standard at each layer of OSI architecture

ISO & IEC standards

Joint Technical Committee 1

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Prof. Sang-Jo Yoo

ITU( Telecommunications Standardization Sector

CCITT

ITU

ITU-T ITU-R

International Telecommunication Union

International Telegraph and Telephone Consultative Committee

15 Study Groups