Computer Networking

Computer NetworkingLocal Area Network(LAN)

ContentsIntroduction to NetworkTypes of Computer NetworkPhysical Types of NetworksServer RolesNetwork TopologiesNetwork HardwareNetwork DevicesBandwidthCSMA/CDOSI ModelOSI LayersPacket Creation and TransmissionTypes of Data TransmissionInternet ProtocolsIP AddressIntranet and Extranet

Proxy ServersAny Question

2Introduction to NetworkA computer network, or simply a network, is a collection of computers and other hardware components interconnected by communication channels that allow sharing of resources and information.A network provides two principle benefits: the ability to communicate and the ability to share. A network can consist of two computers connected together on a desk or it can consist of many Local Area Networks (LANs) connected together to form a Wide Area Network (WAN) across a continent.Types of Computer NetworkLAN: A group of interconnected computers under one administrative control group.WAN: A networks that connects LANs in Geographically separated locations. WLAN: Group of wireless devices that connect to access points within a specified area.MAN: metropolitan area network falls in middle of LAN and WAN, It covers large span of physical area than LAN but smaller than WAN, such as a city.SAN: Storage area network connects servers to data storage devices .CAN: Campus Area Network Physical Types of NetworkPhysicaltopology refers to the placement of the network's various components, including device location and cable installation, whilelogicaltopologyshows how data flows within a network, regardless of its physical designPeer-to-peer networks: Devices which are connected directly to each other without any additional networking devices between them. Each device has equivalent capabilities and responsibilities.

Client Server network:In a client/server model, the client requests information or services from the server. The server provides the requested information or service to the client.

Physical Types of NetworkServer RolesIn most common use, aserveris a physical computer (acomputer hardwaresystem) dedicated to run one or more services (as ahost),to serve the needs of the users of other computers on the network. Depending on the computing service that it offers it could be adatabase server,file server,mail server,print server,web server,gaming server, or some other kind of server.Roles of ServerMail ServerDatabase ServerDatabaseFax ServerFile and Print ServerDirectory Services ServerClient ComputerNetwork TopologiesNetwork topologyis the arrangement of the various elements (links,nodes, etc.) of acomputerorbiological network.Essentially, it is the topologicalstructure of a network, and may be depicted physically or logically.BUS Networks:

Network TopologyTerminatorSegment

TerminatorSTAR Network:Hub

10RING Networks:

Network TopologyMESH Network:

Network HardwarePhysicaltopology refers to the placement of the network's various components, including device location and cable installation, whilelogicaltopologyshows how data flows within a network, regardless of its physical design.UTP Cable:

Network HardwareCoaxial CableOuter shield

Insulation (PVC, Teflon)Conducting coreCopper wire mesh oraluminium sleeve

Network HardwareConnector & Jack for UTP Cable

Network DevicesComputer networking devices are units that mediate data in a computer network. Computer networking devices are also called network equipment, Intermediate Systems (IS) or Inter Working Unit (IWU).LAN EquipmentNetwork CardsRepeaters HubSwitchBridgesWAN EquipmentRoutersNetwork CardA network interface controller (also known as a network interface card, network adapter, LAN adapter and by similar terms) is a computer hardware component that connects a computer to a computer network.

LAN Equipment

16RepeaterA repeater is an electronic device that receives a signal and retransmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.

LAN Equipment

HubAn Ethernet hub, active hub, network hub, repeater hub, multiport repeater or hub is a device for connecting multiple Ethernet devices together and making them act as a single network segment.A hub works at the physical layer (layer 1) of the OSI model.LAN Equipment

SwitchA switch is a telecommunication device which receives a message from any device connected to it and then transmits the message only to the device for which the message was meant. This makes the switch a more intelligent device than a hub (which receives a message and then transmits it to all the other devices on its network).LAN Equipment

19BridgeNetwork bridging describes the action taken by network equipment to allow two or more communication networks, or two or more network segments creating an aggregate network. Bridging is distinct from routing which allows the networks to communicate independently as separate networksLAN Equipment

RouterA router is a device that forwards data packets between computer networks, creating an overlay internetwork. A router is connected to two or more data lines from different networks. When a data packet comes in one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey.WAN Equipment

BandwidthBandwidth is the amount of data that can be transmitted within a fixed time period.Bandwidth is measured in bits per second and is usually denoted by the following:bps - bits per secondKbps - kilobits per secondMbps - megabits per second 22CSMA/CDShort for Carrier Sense Multiple Access / Collision Detection, a set of rules determining how network devices respond when two devices attempt to use a data channel simultaneously (called a collision). Standard Ethernet networks use CSMA/CD to physically monitor the traffic on the line at participating stations.If no transmission is taking place at the time, the particular station can transmit. If two stations attempt to transmit simultaneously, this causes a collision, which is detected by all participating stationsCharacteristicsDescriptionAccess MethodCSMA/CDTransfer SpeedStandard Ethernet 10 MbpsFast Ethernet 100 MbpsGigabit Ethernet 1 Gbps (1000 Mbps)

Detects signalTransmits signalCollision detected

CSMA/CDOSI LayerShort for Carrier Sense Multiple Access / Collision Detection, a set of rules determining how network devices respond when two devices attempt to use a data channel simultaneously (called a collision). Standard Ethernet networks use CSMA/CD to physically monitor the traffic on the line at participating stations.If no transmission is taking place at the time, the particular station can transmit. If two stations attempt to transmit simultaneously, this causes a collision, which is detected by all participating stationsOSI Model The Open Systems Interconnection (OSI) model (ISO/IEC 7498-1) is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Communication functions are grouped into logical layers. A layer serves the layer above it and is served by the layer below it.OSI LayersApplication LayerPresentation LayerSession LayerTransport LayerNetwork LayerData Link LayerPhysical LayerOSI LayersApplication LayerResponsibilities:-Provides virtual end-to-end links between peer processes.-End-to-end flow controlIssues:-Headers-Error detection -Reliable communicationOSI LayersResponsibilities:-Data encryption-Data compression-Data conversionMany protocol suites do not include a Presentation Layer.Presentation LayerOSI LayersResponsibilities:-Establishes, manages, and terminates sessions between applications.Many protocol suites do not include a Session Layer.Session LayerOSI LayersResponsibilities:-Provides virtual end-to-end links between peer processes.End-to-end flow controlIssues:HeadersError Detection Reliable ComminationTransport LayerOSI LayersResponsibilities:- Path selection between end-systems (routing).subnet flow control.-Fragmentation & reassembly-Translation between different network types. End-to-end flow controlIssues:Packet HeadersVirtual Circuits Network LayerOSI LayersResponsibilities:- Provide an error-free communication link.Issues:Framing(Dividing data into chunks)AddressingData Link LayerOSI LayersResponsibilities:- Transmission of raw bits over a communication channel.Issues:Mechanical and electrical interfacesTime per bitDistancesPhysical LayerPacket Creation & Transmission

Types of Data Transmission

UnicastBroadcastMulticastInternet ProtocolNetwork Protocols are the formal description of a set of rules and conventions that govern how devices on the network layer (layer 3 of the OSI model) exchange information. Protocols provide the link by which systems connected to a network may talk to each other For two end systems to talk to each other, they must effectively speak the same language traffic IP AddressAn Internet Protocol address (IP address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing.IP Address S.No.ClassRangeAllocation1A1 126N.H.H.H 2B128 191N.N.H.H 3C192 223N.N.N.H 4D224 239Not applicable 5E240 255Not applicable N = NetworkH = Host IntranetAn intranet is a set of Internet services (for example a web server) inside a local network, i.e. only accessible from workstations of a local network, or rather a set of well-defined networks that are invisible (or inaccessible) from the outside. It involves the use of Internet client-server standards (using TCP/IP) protocols such as, for example, the use of Web browsers (HTTP protocol-based client) and Web servers (HTTP protocol), to create an information system inside of an organization or enterpriseExtranetAn extranet is an extension of the information system of the company to its partners located outside of the network. Access to the extranet must be secured to the extent that the same provides access to the information system for persons located outside of the enterprise. Intranet & ExtranetIntranet

Extranet

InternetProxy Server

InternetProxy ServerAuthorizedWeb Site

Restricted Web Site

LAN

LAN

LAN

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