introduction
TRANSCRIPT
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
◆ 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