计算机网络与因特雷双语结业论文.doc

Graduation ProjectWriter: qinxuejuan Student ID: 0907240410University: Northeast Dianli University College: Automation Engineering Institute Profession: Automation 094Title: Computer Networks Design Conductor: Chen Dongmiao Marker: Chen Dongmiao December 20th, 2011contentsAbstract4PartLearn form this semester5Chapter1 Network Applications and Network Programming summary5 Chapter 2 Data communications summary6 2.1 The conceptual pieces of a communication system6 2.2 The basic types of Multiplexing72.3Access and interconnection technologies8Chapter 3 Packet switching and network technologies summary9 3.1 LAN concepts9 3.2 LAN topology9 3.3 WAN tecnology10 3.4 The IEEE MAC Sub-Layer123.5 Distributed Route Computation15Chapter 4 Internetworking with TCP/IP summary17Part Project185.1 Software configuration20 5.2 VLAN set access permissions215.3 List of equipment and models225.5 WAN design235.6 router245.7 Feelings of the Classes25Bibliography26AbstractThrough the structural wiring method, can be connected togethere multiple hub,forming a large-scale LAN, the LAN most used mixed topology,and tree and star in the majority.Each floor we use one router and the five routers connect with a switch.Structured cabling system is the building or buildings within the transmission network both make the data communications equipment, switching equipment, and other information management systems connect to each other, but also enable these devices interconnected with the external communications network, including building to the external the network line connection point, and work area of all cables between the data terminal, and associated wiring components. A good structured cabling system equipment for its services, a certain independence, and can interconnect a number of different communications devices, such as data terminals, PC and the host, and public installations.Key words: WAN LAN network routerPart Learn form this semesterThis term,we studied for four parts of computer networks and internets, incluing: Network Applications and Network Programming Data communications Packet Switching and Networking technologies Internetworking with TCP/IPChapter1 Network Applications and Network Programming summaryIn the Internet,all services are supplied by applications,which use either a stream paradigm or a message paradigm to communicate.The stream paradigm guarantees to deliver a sequence of bytes in order, but can choose how many bytes to pass to a receiver in each batch. The ,message paradigm preserves boundaries,but allows messages to be lost,duplicated, or delivered out-of-order.The basic communication model used by network applications is known as the client-server model. A program that passively waits for contact is called a server,and a program that actively initiates contact with a server is called a client.Each computer is assigned a unique address,and each service, such as email or web access,is assigned a unique identifier known as a protocol port number.When a server starts, it specifies a protocol port number; when contacting a server,a client specifies the address of the computer on which the server runs as well as the protocol port number the server is using.A single client can access more than one service,a client can access servers on multiple machines,and a server for one service can become a client for other services.Designers and programmers must be careful to avoid circular dependencies among servers.An Application Program Interface(API) specifies the details of how an application program interacts with protocol software.Although details depend on the operating system,the socket API is a de facto standard.A program creates a socket, and then invokes a series of functions to use the socket.A server using the stream paradigm calls socket functions: socket, bind, listen, accept, recv,send,and close: a client calls socket, connect, send , recv, and closeChapter 2 Data communications summary2.1 The conceptual pieces of a communication systemTo understand data communications,imagine a working communication system that accommodates multiple sources of information,and allows each source to send to a separate destination. It may seem that communication in such a system is straightforward.Each source needs a mechanism to gather the information,prepare the information for transmission ,and transmit the information across the shared physical medium.Similarly, a mechanism is needed that extracts the information for the destination and delivers the information. Figure 2.1 illustrates the simplistic view.Channel decoderDecryptorSource decoderDestination 1Channel decoderDecryptorSource decoderDestination 1Information sourceSource encoderEncrytor(scrambler)Channel encoderChannel encoderEncryptor (scrambler)Source encoderInformation source NdemedulaterPhysical channel(noise&interference)modulatormultiplexordemultiplexorFigure 2.12.2 The basic types of MultiplexingThere are four basic approaches to multiplexing that each have a set of variationgs and implementions.Frenquency Division MultiplexingWavelength Division MultiplexingTime Division Multiplexing Code Division MultiplexingTime and frequency division multiplexing are widely used. Wavelength division multiplexing is a form of frenquency division multiplexing used for optical fiber. Code division multiplexing is a mathematical approach used in cell phone mechanisms.2.3Access and interconnection technologiesA variety of technologies are used to provide Internet access.They can be divided into two broad categories based on the data rate they provide:NarrowbandBroadbandNarrowbandDialup telephone connectionsLeased circuit using modemsFractional T1 data circuitsISDN and other telco data servicesBroadbandDSL technologiesCable modem technologiesWireless access technologiesData circuites at T1 speed or higherChapter 3 Packet switching and network technologies summary3.1 LAN conceptsLAN is dispersed within a limited geographical area multiple computers connected through the transmission medium of communication networks, through full-featured network software to achieve communication between computers and share resources with each other.LAN is usually in the tens of meters to a few kilometers within a local area network can accommodate several to several thousand computers.Now look at the characteristics according to the LAN, local area network has the following features:LAN distributed in relatively small geographic range.Because it uses a different transmission capacity of transmission media, so the LAN transmission distance is also different.LANs are often used for a particular group.For example, a company, a unit of a block of flats,certain schools.3.2 LAN topology3.2.1Star topology A star topology resembles a wheel with the network itself corresponding to a central hub, and the link to individual computers corresponding to spokes.3.2.2 A bus topologyA bus topology consists of a single, shared cable to which many computers attach. When it uses a bus, a computer transmits a signal that all other computers attached to the bus receive. 3.2.3 A ring topologyA ring topology consists of computers connected in a closed loop. The first computer connects to the second, the second connects to the third, and so on, until the last computer connects back to the first. A star topology resembles a wheel with the network itself corresponding to a central 3.3 WAN tecnology WAN-wide area network, is a set of packet switches are interconnected to form a wide area network. A switch usually has multiple I/O connectors, making it possible to form many different topologies and connect multiple computers. WAN also called remote nets. Usually jumper great physical limits, the coverage range from a few tens of kilometers to thousands of kilometers, it can connect to several city or country, or across several chau and can provide telecommunication, forming an international long distance network.WAN is present on the network, a division of the most common network division is according to the scope of computer network and the distance between Internet division, have wan, LAN and metropolitan three types. WAN is relatively wide range covers geography of the data communication network, it often provide conditions using public carrier transmission. The Internet is a huge wan. Usually at the router will have a WAN ports, also refers to access the Internet such relatively wider data communications network of port.3.3.1WAN interface:RJ - 45 portUsing RJ - 45 port can also build wan and LAN VLAN (between virtual local area network), and establish and remote network or the Internet connection. If use routers for different VLAN provide routing, can use directly twisted-pair cable connected to different VLAN port. But take note here - 45 port RJ which connected network is generally not is the maximum distance that 10base-t, but 100Mbps fast Ethernet above. If you must through fiber connection to the long distance network, or connection is other types of port, when they need to resort to transceiver repeater can realize the connection between each other. As shown in figure for Fast Ethernet (Fast Ethernet) port.AUI portAUI port is used with coarse coaxial cable connected network interface, actually AUI port is also often used with wan connection, but this kind of interface type in wan USES it is less. In Cisco2600 series routers, provided with AUI RJ - 45 two wan connection, user can choose according to their own needs proper type.3.3.2High-speed synchronous serial interfaceOn a router wan connection, application of port will calculate most synchronous SERIAL ( high-speed *), the port is mainly used to connect currently applied extensively DDN, Frame Relay (Frame Relay), x.25, PSTN (simulated telephone lines) and other network connection modes. In corporate network between sometimes through DDN or x.25 etc wan connection technique for special connection. This synchronization port general requirement rate is very high, because generally speaking through this port the connected network at both ends of the real-time synchronization request. As shown in figure for high-speed synchronous serial interface.3.3.3Asynchronous serial interfaceAsynchronous serial port (ASYNC) is mainly applied in Modem or Modem pool connection, used to realize the remote computer via PSTN dialed network. This kind of asynchronous port relative to the introduction of synchronous port is required in loose in rate, because it does not require many network at both ends of the real-time synchronization, only asked to keep continuous can. So we can see when using the Internet is not necessarily website real-time content, but this is not important, because after all this delay is very small, it is essential to browse the web page when can maintain normal download. As shown in figure for asynchronous serial interface.ISDN BRI portISDNBRI port for ISDN lines through Internet or other routers and remote network connection, which can realize 128Kbps communications rate. ISDN have two rates connections, one kind is ISDN BRI (basic rate interface), another kind is ISDN PRI (the group of rate interface), ISDN BRI port is using RJ - 45 standard, and the connection to use ISDNNT1 RJ - 45 - to - RJ - 45 straight-through. As shown in figure for ISDN BRI port.3.3.4 WAN connection type:Leased Lines: general Leased is special point-to-point circuit, for flow relatively fixed and closer distances occasions, cost is higher, (currently can to China telecom, China mobile, China unicom, radio and television companies such as leased lines).Circuit switching: according to the demand Switched connection is established and allow for these connections until they released such a process, such as telephone network. Packet switching/Packet switching: sharing lines. Use of packet-switched way connecting wan, need to build a virtual circuit.Broadband Access (Broadband Access) : ADSL and Cable.3.4 The IEEE MAC Sub-LayerThe IEEE MAC layer contains protocols that control access to a shared medium. Channelization protocols consist of extensions to time, frequency,and code division multiplexing; the extensions are known as Frequency,Time, and Code Division Multi-Access.Static or dynamic channel allocation is possible.Controlled access protocols allow independent stations to engage in statistical multiplexing. Polling uses a central controller that repeatedly checks whether stations are ready to send a paket. A reservation system,often used with satellites, requires stations to declare whether they are ready for the next round of transmission. Token passing, often used with a ring topology,passes a control message among stations; a station can transmit a packet when it receives the token.Random access protocols allow stations to contend for access. The historic ALOHA protocol used two frequencies, one for inbound and one for outbound transmissions; if a station did not receive a copy of its packet ,the station retransmitted.Ethernet uses Carrier Sense Multi-Access with Collision Detection(CSMA/CD)to permit access to a shared cable. In addition to preventing a station from transmitting while another transmission is in progress, the protocol uses binary exponential backoff to recover from collisions.Because some stations are hidden from others, wireless LANs use Carrier Sense Multi-Access with Collision Avoidance(CAMA/CA). Before transmission of a packet from one computer to another, each of the two computers sends a short control message, which allows all computers in range of the two to know that a transmission is about to occur.3.4.1 CSMA/CDIn 1973, researchers at Xerox PARC created an extremely successful network technology that used a random access protocol. In 1978，a standard (informally called the DIX standard) was created by Digital Equipment Corporation, Intel, and Xerox. Known as Ethernet, the original Ethernet technology consisted of a single long canle to which computers attach. The cable served as a shared medium-instead of broadcasting radio frequency transmissions through the atmosphere, Ethernet transmitted signals down a cable. Furthermore, instead of using two freuencies and a central transmitter, Ethernet allows all communication to proceed across the shared cable.Despite their differences,Ethernet and ALONAnet had to solve the same basic problem:if two stations attempt to transmit at the same time, the signals interfere and a collision occurs.Ethernet offered three innovations in the way collisions are handled:Carrier senseCollision detectionBinary exponential backoffThe combination of techniques described above is known by the name Carrier Sense Multi-Access with Collision Detection.(CSMA/CD) Algorithm 3.1 summarizes CSMA/CD.Algorithm 3.1Purpose: Use CSMA/CD to send a packetMethod: Wait for a packet to be ready; Wait for the medium to be idle (carrier sense); Delay for the interpacket gap; Set variable X to the standard backoff range, d; Attempt to transmit the packet (collision detection); While (a collision occurred during previous transmission) Choose q to be a random delay between 0 and X; Delay for q microseconds; Double X in case needed for the next round; Attempt to retransmit the packet (collision detection);Algorithm 3.13.4.2 CSMA/CATo ensure that all stations share the transminssion media correctly, wireless LANs use a modified access protocol known as Carrier Sense Multiple Access With CollisionAvoidance (CSMA/CA). Instead of depending on all other computers to receive all transmissions, the CSMA/CA used with wireless LANs triggers a brief transmission from the intended receiver before transmitting a packet. The idea is that if both the sender and receiver transmit a message, all computers within range of either will know a packet transmission is beginning. Figure 3.1 illustrates the sequence.1: ready to send2: clear to send 3: packet transmission2: clear to sendComputer 1Computer 2Computer 3Figure 3.1In the figure, computer 3 sends a short message to announce that it is ready to transmit a packet to computer 2,and computer 2 responds by sending a short message announcing that it is ready to receive the packet. All compters in the range of computer 3 receive the initial announcement, and all computers in the range of computer 2 receive the response. As a result,even though it cannot receive the signal or sense a carrier, computer 1 knows that a packet transmission is taking palces3.5 Distributed Route ComputationAll packet switches must participate in distributed route computation. There are two general forms:Link-State Routing (LSR), which uses Dijkstras algorithmDistance-Vector Routing (DVR), which uses another approach3.5.1 Link-State Rou