英语专业毕业论文公司局域网络连接设计.doc

CONTENTSPART ONELAN Technologies And WAN TechnologiesChapter 1 LAN Technologies1.1 LAN overview 51.1.1 LAN concept51.1.2 LAN composition61.2 LAN technology71.2.1 System structure and agreements71.2.2Transmission medium71.2.3 network topology81.2.4Router111.2.5Gateway13Chapter 2 WAN Technologies2.1 WAN overview142.1.1 WAN overview142.1.2 WAN type152.2 WAN technologies152.2.1 WAN technologies152.2.2 Packet switching162.2.3 Routing172.2.4 Congestion control212.2.5 Packet switching16PART TWO DESIGNChapter 3 Lan Design3.1 Network selection263.2 network design273.3 Summary33AbstractIts includes three parts: LAN Technologies, WAN Technologies and company local area network connection design.LAN composition is divided into network hardware and network software two parts.Network hardware mainly includes web server, workstations, peripherals, network interface card, transmission medium. LAN network software, mainly including agreement software and network operating system. A router is the network layer of network interconnection equipment. The typical private sidings network using special analog circuits, E1 line etc.WAN technologies Network can be divided into exchange network and broadcast networks, in exchange network is divided again circuit switched network and packet switching network (including frame relay and ATM); While in radio network includes bus network, ring network and the astral network. (3) congestion control: into the network traffic must with network throughput coordinated to get effective and stable and good performance.(2) a packet-switching network can implement data rate conversion.The routing algorithm suitable for network topology more stable and network the relatively small size of the network. (2) dynamic routing algorithm in dynamic routing algorithm used in:, each router through its neighbor's communication, and constantly learning network state. In all of the packet switching network use some adaptive routing technology. This algorithm applies only to small-scale network.(2) distributed routing algorithm: in distributed routing algorithm, each router their respective routing computation. This algorithm can gradually and network topology changes in adaptation.Deviation routing algorithm can work well in there are rules of network topology. Network selection1250 units or more companies can take access layer, convergence layer, switching layer 3 network layer design. network backbone with six-core multimode fiber. It can effectively expand their network bandwidth, eliminating network collisions, improve network transmission efficiency. Key word: LAN WAN computer network automation network connectionPART ONELAN Technologies And WAN TechnologiesChapter 1 LAN Technologies1.1 LAN overviewIn the early 1980s, when most companies are still in use web host, the computing facilities happened two changes. First, the number of PCS common enterprise increased, leading to flow increase. Secondly, some engaged in engineering, familiar with computer user began to use their own workstation work, they require the company to information management departments to provide a link to host network. These changes to the enterprise network has brought new challenges.Flow increases, makes the enterprise again considering all that produce traffic information is how to use. They found that about 80% of the information from the enterprise internal, only 20% of the information needs and enterprise outside of the site in exchange. Therefore, need a emphatically resolve limited geographical scope communication network, so there will be a LAN (Local Area grow independently, LAN).1.1.1 LAN conceptLAN is a kind of geographical scope limited network is a small area of communication equipment interconnected together of communication network, figure 8-1 is a typical LAN. LAN's main features are: network is classified as one unit, and owned by geographic coverage and site limited number. The traditional LAN wan has higher than the data rate, low delay, smaller ber. But as the optical fiber technology in the widespread use of current wan wan also has high data rate and smaller ber.Figure 1-1 LANLAN responsible for connecting the sender and the receiver, and it can identify all the node on the network. The traditional LAN using Shared medium, and each of these devices connected to the same cable (until 1987 LAN are used in coaxial cable, then appeared other media LAN standard). In order to support multimedia applications, a desktop to the bandwidth of the increasing demand, therefore LAN from Shared media structure to use hubs or switch structure. Using these devices can make the workstation has his own special connection, thereby improving the workstation's available bandwidth.LAN can be deployed in pairs and other network (Peer to Peer), also can deploy into based on the server's network. The former each node is equal (each node according to his own way to handle and store data), while the latter only a computer (i.e. server) is responsible for the information stored in the computer, and other information obtained from the server.1.1.2 LAN composition LAN composition is divided into network hardware and network software two parts.Network hardware mainly includes web server, workstations, peripherals, network interface card, transmission medium. According to the transmission medium and topology is different, LAN need hubs (on), concentration device (concentrator) equipment, if you want to network interconnection, still need Bridges and routers and gateways, and nets interconnections between hardware circuitry, etc.(1) server: on a LAN, the server can its CPU, memory and disk, printer, data resources available to all workstations using, and is responsible for these resources management, coordinate to network users of these resources use. Therefore required server with high performance, including faster processing speed, the larger the memory, large capacity and faster access speed of disk, etc.(2) workstation: network workstation choice is simpler, any microcomputer as network workstation, currently use most network workstation may be based on the Intel CPU microcomputer, this is because this kind of microcomputer, the largest number of users, and most most network products.(3) peripherals: peripherals mainly refers to the Internet for network users sharing external devices on the network, usually, Shared peripherals including printer, MODEM plotter, scanners, etc.(4) network interface card: the network interface card (hereinafter referred to as nic) provide data transmission function, used for computer with cable (namely transfer medium), and then connect the computer access network, so every one computer hooked-up all need a network adapter.(5) :the network interface card transmission medium determines the type of network adopted by the transmission medium, the types of physical and electrical characteristic, signal types, as well as network in each computer access medium method, etc. LAN cable are mainly used in twisted-pair and coaxial cables, optical fiber.LAN network software, mainly including agreement software and network operating system. At present in the personal computer of the most popular is the Windows operating system, can easily finish LAN is established.1.2 LAN technology1.2.1 System structure and agreements American IEEE has specially set up a team of the LAN LAN subject has formulated the American national standards in 1980 February, and the submission international organization for standardization as an international standard drafts, 1984 March got ISO adopted.IEEE802 model and the OSI reference model corresponding relation (see figure 8-2. IEEE mainly to the first, 22 layer has formulated procedures, so LAN IEEE802 model is in the OSI of the physical layer and the data link layer to basic communication function. IEEE802 LAN reference model corresponds to the OSI reference model physical function, mainly, signal encoding, decoding, leading code generation and removal, bits of sending and receiving.1.2.2 Transmission medium That choose transmission medium first factors to consider bandwidth. Want to consider bandwidth on one hand to estimate the LAN need of transmission capacity, namely the server and the client respective traffic demand, usually the size of large quantities of data transferred server, but when a client application of multimedia information needs to be transmitted when, often also need greater bandwidth. On the other hand, we need to consider working group within the flow and the flow between workgroups backbone.Secondly factors to consider is the connection of the cost and degree of difficulty, specifically is installed, mobile, changes needed for the cost and degree of difficulty. E.g. when a LAN need often changes reorganization, the wireless local area network is to support such a dynamic environment of the most appropriate solutions.The third factors to consider anti-interference ability. LAN working environment is different from the transmission medium the anti-jamming ability of demand is also different. When working in strong interference of LAN bad environment, should choose strong anti-interference ability transmission medium, such as optical or coaxial cable, and cannot choose twisted-pair cable or wireless medium.The fourth factors to consider security. Different situations of safety LAN have different requirements, when use of the high demand for security in the situation, cannot use wireless medium, and should consider the invasion of fiber optic cable hard medium.At present, most LAN standard supports multiple media type, but use different media type, the network characteristics of different (such as allowed by the connected device number, data transfer rate, the maximum distance between devices etc.), so need to consider the various factors to choose the appropriate transfer medium as far as possible in order to achieve high costperformance. 1.2.3 network topology LAN topology refers to network nodes and communication lines of geometric sorted, it to the whole network of design, function, economy and reliability are influential, to the LAN generally have five structure: star, total linear, the annular, tree, mesh, etc, as shown in figure 1-2 illustrates.Figure 1-2 LAN topologyBus-control, star and annular general use in baseband LAN, and tree structure commonly used for broadband LAN. Now the LAN, most common physical topology is star, most common logical topology is bus-control (logical topology refers to the site is how to switch between signal).(1) bus-control topologyBus-control topological all nodes are through the corresponding hardware interface connected to a passive public bus, any node sends out the information can be transmitted along the bus, and was on the bus for any other node receiving, its transmission from sending point to both ends direction, which is a kind of diffusion transfer AnBoShi structure, as shown in figure 1-3 shows. Each node in the network card has a transceiver, when sending node to send the destination address of a node with the interface autogeneration, this node namely receive this information.Figure 1-3 bus-control LANEach site can according to access control principle on a bus protected reliably against detective and signalling. But at a certain hour, and there is only one computer sends a signal on a bus. Signal from the upper began in two directions spread on the bus. The others on the network site will receive send site signal. Because the data is sent to the entire network, it can transfer from one end of the bus to the other side. If transmit signals are not suspend but to allow continued spread word, it will come up in the bus cycle again and again teleport, thus will deter other computer sending signals. Therefore, in the signal arrive destination must be suspended. Bus at both ends of the containing termination device (i.e. termination resistors), which absorb useless signals, thus make the other computer can send signal.Bus structure is the advantage of simple installation, easy to extend, high reliability, a node damage, will not affect the entire network work, but due to share a bus, so want to solve two nodes simultaneously to a node to send information to the collision problems, the real-time demand higher occasions don't apply. In addition, cable fault but also can affect many users, and a network of the flow rate will be reduced.(2) tree topologyTree topology, the roots of a tree is a head end, or called frequency conversion equipment. With roots trunk cable, is linked to the main line of various branch cable connection cables, cable and user equipments is connected to a branching cables, as shown in figure 8-5 below.Figure 1-4 tree LANTree structure is always linear outspread, it is a layered branch of structure. A branch or node fault not affect other branch and node to work properly. Like bus structure is same, it is also a kind of AnBoShi network. Any node to send information, other nodes can receive. But the tree structure defect is lines as total nano-dimension high utilization rate.(3) with loop topologyThe annular topology structure, each node in point-to-point way links, form a closed loop structure, as shown in figure 8-6 below. Signal in each site receiving, regeneration, and transmitted to ring next node, and data transmission in ring is in one direction.The annular topological structure of a advantage is able to signals to the far distance, this is because each site can regenerate the signal. This structure is easy to realize the distributed control and all computers have equal access. Another advantage of annular structure is good real-time, information throughput, nets, the perimeter 200km, node can reach can reach several hundred. But because of loop is closed, so expand inconvenience.The annular topological drawback is on site trouble comparison sensitive (namely a site fault may destroy the entire loop). In addition, the annular network not easily, and network fault isolation will affect local variation of the whole network operation. In order to improve the reliability, can be in a ring network using 2-ring or polycyclic etc redundancy measures. The current ring structure also adopted a multi-channel access components maus, when a node is at fault, can automatically bypass, isolating fault point, and makes the reliability is improved.Figure 1-5 annular LAN(4) star structureStar with the central node structure for the center, a node to another node to send data to the central node, must establish a connection request once, the two nodes is a special connection, information transmission through central node storage - connecting to complete, star struct