COMPUTER NETWORKS C-138 Self Learning Material Directorate of Distance Education SWAMI VIVEKANAND SUBHARTI UNIVERSITY MEERUT-250005 UTTAR PRADESH SIM Module Developed by ; Ramesh Bangia has been writing computer books for the one decade. He has written books on various topics of computers, mainiy, related to the software. He has to his credit books pertaining to school levels, both middle and secondary level; books for Department of Electronics' O Level papers; books for various polytechnics; books for gerieral software usage. Prior to this he edited a software magazine called Software Today. Reviewed by the Study Material Assessment Committee Comprising: 1. Dr. V.B. Sahal, Vice Chancellor 2. Dr. G.S. Bhatnagar, Pro-Vice Chancellor 3. Dr. Mohan Gupta 4. Mr. Sumit Bhatnagar 5. 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Tel: 43532500, E-mail: [email protected] C—8013/014/01 DEM-2167-66.40-COMPUTER NETWORKS C-138 l‘niiirtl nl: Akashdcep Ivuts’ri>riscs, CONTENTS Units Page No. I. Introduction to Computer Networks 1-54 2. Introduction to IPV6 55-76 3. Mobility in Network 77-102 4. TCP Extensions 103-130 5. Network Security 131-162 i \ SYLLABUS COMPUTER NETWORKS C-138 Unit 1; Introduction: Overview of computer network, seven-layer architecture, TCP/IP suite of protocol, etc. Mac protocols for high-speed LANs, MANs & WIRELESS LANs. (For example, FDDl. DQDB. HIPPI. Gigabit Ethernet, Wireless Ethernet etc.) Fast,access technologies. (For example, ADSL, Cable Modem, etc.) Unit 2: IPv6: why IPv6, basic protocol, extension & option, support for QoS, security, etc, neighbor discovery, autoconfiguration, routing. Change to other protocols. Application programming interface for Ipv6. 6bone. Unit 3: Mobility in network. Mobile. Security related issues. IP Multicasting. Multicasting routing protocols, address assignments, session discovery, etc. Unit 4; TCP extensions for high-speed networks, transaction-oriented application, other new option in TCP. Unit 5: Network security at various layers. Secure-HTTP, SSL, ESP, Authentication header. Key distribution protocols. Digital signatures, digital certificates. Iraroduction lo Computer Networks Unit 1 NOTES INTRODUCTION TO COMPUTER NETWORKS STRUCTURE 1.1 Overview of Computer Networks 1.2 Seven Layer Architecture 1.3 TCP/IP suite of Protocol 1.4 Mac protocols for high speed 1.5 LANs 1.6 MANS 1.7 Wireless LANs 1.8 FDDI 1.9 DQDB 1.10 HIPPI 1.-11 Gigabit Ethernet 1.12 Wireless Ethernet • 1.13 Fast access technologies •1.14 ADSL 1.15 Cable Modem Summary Self Assessment Questions Further Readings Learning Objectives After going through this unit, students will be able to: • know about the seven layers of computer architecture V • know about the various networks like LAN, MAN and WAN. • learn about Cable Modem. • learn about the fast access technologies • learn about Gitabit Ethernet Self Instructional Materia! 1 Computer Networks 1.1 OVERVIEW OF COMPUTER NETWORKS When more than two computers are connected to each other and sharing information, resources and remote systems then this is called Networking. NOTES Technical deiinitions: “A network of data processing nodes that are interconnectedfor the purpose of data communication”. “An interconnection of three or more communicating entities”. 1.1.1 Classification of Computer Networks 1.1.1.1 Network Layer In this computer networks follow the industry standards of OSI reference model and TCP/IP model. Where as OSI is of seven layers and TCP/IP is defined in five layers. Ll.1.2 Scale It can be classified as: • Local area network (LAN) • Campus area network (CAN) • Metropolitan area network (MAN) • Wide area network (WAN). • Personal area network (PAN) 1.1.1.3 Connection Method The connection methods available are: • Ethernet • Power line communication • Wireless LAN • HomePNA 1.1.1.4 Functional Relationship This exists between the network elements: • Peer-to-peer • Client-server 1.1.1.5 Network Topology It is a logical layouts of the network. Topologies are: • Star network • Ring network • Bus network 2 SelfInstructional Material • Tree network Incroductionto Computer Networks • Star-bus network • Mesh network 1.1.1.6 Services NOTES It provides following services: • Wireless community network • Server • Storage area networks • Process control networks • Value-added network 1.1.1.7 Protocol On network protocols are used as communication language. Several types of protocols are available: • TCP/IP • Network IPX/SPX 1.1.2 Types of Networks Following is the list of the most common types of computer networks in order of scale. 1.1.2.1 Persona! A rea Network (PA N) PAN is used for communication among the personal devices (intrapersonal communication), or for connecting to a higher level network and Internet. The reach of a PAN is typically a few meters. A personal area network (PAN) is used for communication among computer devices. For example, • Telephones 1?: □tB Self Instructional Material 3 Computer Networks • Personal digital assistants Personal area networks may be wired with computer buses such as USB and FireWire. A wireless personal area network (WPAN) can also be made possible with network technologiw'tudi as IrDA and Bluetooth. Local Area Network (LAN) NOTES A network covering a small geographic area, like a home, office, or building. Current LANs are most likely to be based on Ethernet technology. The defining characteristics of LANs, in contrast to WANs (wide area networks), include their much higher data transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines. 1.1.2.3 Campus Area Network (CAN) A network that connects two or more LANs but that is limited to a specific (possibly private) geographical area such as a college campus, industrial complex, or a military base. A CAN, may be considered a type cf MAN (metropolitan area network), but is generally limited to an area that is smaller than a typical MAN. l^J^i^^^^'^etropolitan Area Network (MAN) \ that connects two or more Local Area Networks or CANs together but does not extend beyond the boundaries of the immediate town, city, or metropolitan area. Multiple routers, switches & hubs are connected to create a MAN LL2.5 Wide Area Network (WAN) A WAN is a data communications network that covers a relatively broad geographic area and that often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer. 1.1.2.6 Internetwork Two or more networks or network segments connected using devices that operate at layer 3 (the ‘network’ layer) of ffie OSI Basic Reference Model, such as a router. Any interconnection among or between public, private, commercial, industrial, or governmental networks may also be defined as an internetwork. 1.1.2.7 Internet A specific internetwork, consisting of a worldwide interconnection of governmental, academic, public, and private networks based upon the Advanced Research Projects Agency Network (ARPANET) developed by ARPA of the U.S. Department of Defense - also home to the World Wide Web (WWW) and referred to as the ‘Internet’ with a capital ‘I’ to distinguish it from other generic internetworks. 1.1.2.8 Extranet A network or internetwork that is limited in scope to a single organization or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities (e.g., a company’s customers may be provided access to some part of its intranet thusly creating an extranet while at the same time the customers may not be considered ‘trusted’ from a security standpoint). Technically, an extranet may also be categorized as a G\N, MAN, WAN, , 4 Self Instructional Material . or other type of network, although, by definition, an extranet cannot consist of a Imroduction to Computer single LAN, because an extranet must have at least one connection with an outside Networks network- Intranets and extranets may or may not have connections to the Internet. If connected to the Internet, the intranet or extranet is normally protected from NOTES being accessed from the Internet without proper authorization. The Internet itself is not considered to be a part of the intranet or extranet, although the Internet may serve as a portal for access to portions of an extranet. 1.1.3 Basic Hardware Components All networks are made up of basic hardware building blocks to interconnect network nodes, such as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers. In addition, some method of connecting these building blocks is required, usually in the form of galvanic cable (most commonly Category 5 cable). Less common are microwave links (as in IEEE 802.11) or optical cable (“optical fiber”). IJ.3.1 Network Interface Cards A network card, network adapter or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network.