fall 2008csci 690 csci-690 c omputer networks: shrinking the globe one click at a time lecture 2...

New York Institute of Technology

Engineering and Computer Sciences

Fall 2008 CSCI 690

CSCI-690Computer Networks:

Shrinking the globe one click at a time

Lecture 2

Khurram Kazi



Fall 2008 CSCI 690 2

Major sources of the slides for this lecture

Slides from Tanenbaum’s and William Stallings’ website are used in this lecture




Mankind and Communication “O mankind! We have created you from a single (pair)

of a male and female, and have made you into nations and tribes, so that you may know each other…” [Quran 49.13] When one ponders over how we get to know each other;

certain thoughts come to mind. As we venture outside our own region or domain, we tend

to follow certain protocols that allow us to communicate with each other.

Try to use common language that both parties understand Sign language Draw pictures, use hand gestures…

In short we find a command ground or similar footing which to build a communication platform on, even though we may come from diverse cultures and background




Mankind and Communication Just as we have diversity in mankind,

we have disparate, ever-evolving communications networks

These networks are evolving towards providing seamless connectivity between different platforms and applications so that they cater to our insatiable need to communicate

An integral component of networking is PROTOCOLS




OSI: A Model developed by International Standards Organization (ISO)

Open Systems InterconnectionDeveloped by the International

Organization for Standardization (ISO) has seven layers

Is a theoretical system delivered too late!

TCP (Transmission Control Protocol) /IP is the de facto standard




Networking Reference Models

The OSI Reference Model

The TCP/IP Reference Model




TCP/IP Protocol Architecturedeveloped by US Defense Advanced

Research Project Agency (DARPA) for ARPANET packet switched networkused by the global Internetprotocol suite comprises a large

collection of standardized protocols




OSI vs. TCP/IP

The OSI & TCP/IP reference model.




Reference Models

Protocols and networks in the TCP/IP model initially.



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Key Elements of a Protocol

syntax - data format semantics - control info & error

handling timing - speed matching & sequencing



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Simplified Network Architecture



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TCP/IP Layers

no official model but a working one Application layerHost-to-host, or transport layer Internet layerNetwork access layerPhysical layer



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Physical Layer

concerned with physical interface between computer and network

concerned with issues like:characteristics of transmission mediumsignal levelsdata ratesother related matters



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Network Access Layer

exchange of data between an end system and attached network

concerned with issues like :destination address provision invoking specific services like priorityaccess to & routing data across a network link

between two attached systemsallows layers above to ignore link specifics



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Internet Layer (IP)

routing functions across multiple networks

for systems attached to different networks

using IP protocol implemented in end systems and

routers routers connect two networks and

relays data between them



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Transport Layer (TCP)

common layer shared by all applications

provides reliable delivery of data in same order as sent commonly uses TCP



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Application Layer

provide support for user applicationsneed a separate module for each type

of application



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Operation of TCP and IP



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Addressing Requirements (will discuss at length in later lectures)

two levels of addressing requiredeach host on a subnet needs a unique

global network address its IP address

each application on a (multi-tasking) host needs a unique address within the hostknown as a port



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Operation of TCP/IP



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Transmission Control Protocol (TCP)

usual transport layer is (TCP)provides a reliable connection for

transfer of data between applications

a TCP segment is the basic protocol unit

TCP tracks segments between entities for duration of each connection



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TCP Header



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User Datagram Protocol(UDP)

an alternative to TCPno guaranteed deliveryno preservation of sequenceno protection against duplicationminimum overheadadds port addressing to IP



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UDP Header



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IP Header



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IPv6 Header



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TCP/IP Applications

have a number of standard TCP/IP applications such asSimple Mail Transfer Protocol (SMTP)File Transfer Protocol (FTP)Telnet



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Some TCP/IP Protocols



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Network Design: Software & Hardware

Protocol HierarchiesDesign Issues for the LayersConnection-Oriented and

Connectionless ServicesService PrimitivesThe Relationship of Services to

Protocols



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Design Issues for the Layers

AddressingError ControlFlow ControlMultiplexingRouting



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Connection-Oriented and Connectionless Services

Six different types of service.



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Service Primitives

Five service primitives for implementing a simple connection-oriented service.



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Service Primitives (2)

Packets sent in a simple client-server interaction on a connection-oriented network.



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Starting from the bottom layer of the TCP/IP working model

Physical Layer: Getting into the Fundamentals



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The Theoretical Basis for Data Communication

• Fourier Analysis• Bandwidth-Limited Signals• Maximum Data Rate of a

Channel



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Bandwidth-Limited Signals

A binary signal and its root-mean-square Fourier amplitudes.

(b) – (c) Successive approximations to the original signal.



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Bandwidth-Limited Signals (2)

(d) – (e) Successive approximations to the original signal.



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Guided Transmission Data

•Magnetic Media•Twisted Pair•Coaxial Cable•Fiber Optics



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Twisted Pair: Widely used in Telephony and Ethernet cabling

(a) Category 3 UTP.(b) Category 5 UTP.



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Coaxial Cable: Primarily used in Cable networks

A coaxial cable.



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Fiber Optics: Widely used in high speed networks

(a) Three examples of a light ray from inside a silica fiber impinging on the air/silica boundary at different angles.

(b) Light trapped by total internal reflection.



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Transmission of Light through Fiber

Attenuation of light through fiber in the infrared region.



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Fiber Cables

(a) Side view of a single fiber.(b) End view of a sheath with three

fibers.



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Fiber Cables (2)

• A comparison of semiconductor diodes and LEDs as light sources.



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Fiber Optic Networks

A fiber optic ring with active repeaters.



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Wireless Transmission

• The Electromagnetic Spectrum• Radio Transmission• Microwave Transmission• Infrared and Millimeter Waves• Lightwave Transmission



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The Electromagnetic Spectrum

• The electromagnetic spectrum and its uses for communication.



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Radio Transmission

(a) In the VLF, LF, and MF bands, radio waves follow the curvature of the earth.

(b) In the HF band, they bounce off the ionosphere.



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Politics of the Electromagnetic Spectrum

Industrial, Scientific and Medical (ISM) bands in the United States. Originally reserved internationally for the use of RF electromagnetic fields for industrial, scientific and medical purposes other than communications.



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Lightwave Transmission

• Convection currents can interfere with laser communication systems.

• A bidirectional system with two lasers is pictured here.



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Communication Satellites

• Geostationary Satellites• Medium-Earth Orbit Satellites• Low-Earth Orbit Satellites• Satellites versus Fiber



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Communication Satellites• Communication satellites and some of their properties,

including altitude above the earth, round-trip delay time and number of satellites needed for global coverage.



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Communication Satellites (2)

The principal satellite bands.



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Public Switched Telephone System

• Structure of the Telephone System

• The Politics of Telephones• The Local Loop: Modems, ADSL

and Wireless• Trunks and Multiplexing• Switching



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Structure of the Telephone System

(a) Fully-interconnected network. (Mesh network)(b) Centralized switch.(c) Two-level hierarchy.



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Structure of the Telephone System (2)

A typical circuit route for a medium-distance call.



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Major Components of the Telephone System

• Local loops Analog twisted pairs going to houses and

businesses

• Trunks Digital fiber optics connecting the switching

offices

• Switching offices Where calls are moved from one trunk to

another



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The Local Loop: Modems, ADSL, and Wireless

• The use of both analog and digital transmissions for a computer to computer call. Conversion is done by the modems and codecs (CoDecoder).



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Modems

(a) A binary signal

(b) Amplitude modulation

(c) Frequency modulation

(d) Phase modulation

fall 2008csci 690 csci-690 c omputer networks: shrinking the globe one click at a time lecture 2...

Documents

tcpip reference model

standard slide

background slide

tcpip model

khurram kazi slide

osi tcpip reference

osi reference model

network link