CS3505:CS3505:

The Internet and the Information The Internet and the Information Highway Highway

INTRODUCTIONINTRODUCTION

CS3505 ObjectivesCS3505 Objectives

◆ make better use of the Internet

◆ make better use of all telecom, data networks

◆ understand basic Internet architecture

◆ background, evolution of Internet

CS3505 Admin detailsCS3505 Admin details

◆ lab assignments and homeworks required for passing grade

◆ class participation required, important part of class

◆ exam or graded homework, project for letter grade

introduction: CS3505introduction: CS3505

◆ network examples

◆ network definitions

◆ classifications of networks

◆ layered models (high level)

◆ purposes of networks

◆ network industries and standards

◆ communication protocols

Examples of NetworksExamples of Networks

◆ telephone networks

◆ LANs : ethernet, token ring

◆ ARPANet/MILNET WANs

◆ Cable TV networks

◆ Cellular phone networks

◆ The INTERNET

network definitionsnetwork definitions

◆ network - 2 or more machines connected, sending data to other, using common media and protocols

◆ computer network - network of computers

◆ distributed network - tightly connected, common purpose network. e.g. airline reservation system, real-time battle simulations

network definitionsnetwork definitions

◆ LAN, MAN, WAN (local, metro, wide area networks)

◆ integrated network - different types of traffic (voice, video, email)

◆ internetwork/Internet - interconnected networks using TCP/IP protocol

more network definitionsmore network definitions

◆ intranet - (1) a network internal to an organization, used to connect its clients; (2) a network of nodes separated from the external world by a firewall (ex. NPS Internet)

◆ extranet - a network using the Internet to connect a set of users, operating over a VPN (virtual private network); uses web-browser technology and the Internet to connect a private community of users (ex. private newsletter using Internet; stock-broker)

network classificationsnetwork classifications

◆ geographical coverage (LAN ... WAN)

◆ topology (geometry of links)

◆ switching technique

◆ speed (data rates)

◆ data/information content

geographical coveragegeographical coverage

◆ LAN: Local Area Networks ◆ simpler, less software layers◆ higher data transfer rates (generally)◆ simple routing◆ IEEE standards◆ easily connected via bridges◆ examples: ethernet, token ring

geographical coveragegeographical coverage

◆ MANs

◆ traditional category

◆ cable TV, local phone

◆ DQDB, FDDI

◆ less used, as most networks can be classified into LAN/WAN

geographical coveragegeographical coverage

◆ WANs◆ data speeds slower, in general (this

distinction fading)◆ national, international boundaries◆ includes internetworking◆ ARPANet first example◆ much more complex software◆ OSI model

network topologiesnetwork topologies

◆ star

◆ ring

◆ bus

◆ fully connected

◆ tree

◆ mesh

switching techniques (4)switching techniques (4)

◆ (1) broadcast◆ no switching or routing; 1 station transmits, all

others can receive◆ collisions occur if more than 1 attempts to

transmit at once◆ examples: ethernet LAN and radio networks,

satellites (to some degree)

switching techniquesswitching techniques

◆ (2) circuit switching◆ 3 distinct phases◆ traditional voice network◆ nice for user, but inefficient use of

transmission facilities◆ served traditional voice networks well, but

gradually becoming outdated by new technology

switching techniquesswitching techniques◆ (3) packet switching

◆ fixed packet size◆ much more efficient use of facilities◆ several refinements; fast packet switching

(ATM) is culmination

switching techniquesswitching techniques◆ (4) message switching

◆ sends entire message as single transmission◆ efficiency problems from unbound message

size

network model: ISO 7-layersnetwork model: ISO 7-layers

◆ designed 1970; still heavily used◆ 7 layer model

◆ 1 physical layer◆ 2 data link layer ◆ 3 network layer◆ 4 transport layer◆ 5 session layer◆ 6 presentation layer◆ 7 application layer

modified ISO modelmodified ISO model

1 physical layer - moves a bit from a to b using a physical(electrical, optical, etc.) signal

2 data link - groups bits into frames, or messages, for error control and information

modified ISO modelmodified ISO model

3 network layer - moves packets through the network

3.5 internet layer - routes packets from network to network

modified ISO modified ISO

4 transport - end to end; interface between user apps and the network/internet

7 application - user interface to network, and user services: email, file transfer, world wide web, etc.

IEEE LAN modelIEEE LAN model

◆ specifically for LAN networks

◆ changes in data link, physical layers; others same

◆ layers:◆ physical - similiar but special for LANs◆ MAC: media access control; replaces d.link◆ LLC: logical link control

purposes of networkspurposes of networks

◆ resource sharing

◆ increased reliability

◆ efficiency

◆ communications

◆ future applications: voice, video, data, images, appliances, .... ?

basic network servicesbasic network services

◆ e-mail

◆ file transfers (ftp, etc)

◆ remote login (rlogin, telnet)

◆ WWW (web)

basic network servicesbasic network services

◆ telephone/voice

◆ instant messages

◆ intranets

◆ extranets

network ing industrynetwork ing industry

◆ originally two separate, different industries - computers/communications

◆ computer: IBM, DEC, Sun, Apple, Cray, SGI, Compaq, Dell, Gateway, Microsoft, etc

◆ communications: AT&T, Sprint, MCI-WorldCom, RBOCs, GTE, other phone companies, etc.

network ing industrynetwork ing industry

◆ 2 industries have been merging◆ signs of the merging

◆ initial purpose of each ◆ signals◆ importance of each to the other◆ research labs◆ Sun’s logo “the network is the computer”

industry sectors industry sectors

◆ Computer Industry ◆ mainframes, “big” computers - IBM, Cray◆ mid-size, workstations - Sun, SGI, (DEC, Tandem)◆ personal computers (manufacturers) -Compaq,

Dell, Gateway◆ PCs - software - Microsoft, Apple ◆ semiconductors for PCs - Intel, AMD

industry sectorsindustry sectors◆ Communications

◆ long distance telephone (ATT, Sprint)◆ local telephone (Pacific Bell, etc.)◆ telecom. equipment (Lucent, Nor. Telecom)◆ internet service providers (AOL, etc)◆ radio, wireless data, satelite, etc

standards for networksstandards for networks

◆ reasons for standards

◆ advantages

◆ disadvantages

◆ standards organizations

communication protocolscommunication protocols

◆ protocol: the algorithm or procedure used for communication between processes at the same layer

◆ examples: telephone call; e-mail

◆ protocol processes make use of lower layers as a service.

◆ heart of communications process

communication protocolscommunication protocols◆ some things protocols do

◆ bit interpretation to signals

◆ group bits into messages

◆ error detection and correction

◆ synchronization

◆ make more efficient use of networks facilities

communication protocolscommunication protocols

◆ three basic phases of data communications1. connection establishment2. data transfer3. connection termination

◆ connection-oriented/connectionless