計(jì)算機(jī)網(wǎng)絡(luò)與因特網(wǎng)論文(英文版).doc

MENU1、LAN technology41.1 LAN Overview41.1.1 Emergence and development of local area network41.1.2 LAN Features41.1.3 LAN components51.1.4 LAN Architecture and IEEE802 standard51.1.5 Media access control methods61.2 Ethernet71.2.1 the technical characteristics of the Ethernet81.2.2 IEEE802.3 Ethernet architecture81.2.3 10Mbps Ethernet81.3 Fast Ethernet101.3.1 IEEE802.3u Fast Ethernet101.3.2 100VG-AnylAN111.4 Fiber Distributed Data Interface FDDI111.4.1 FDDI dual ring structure111.5 Switched Ethernet111.5.1 A problem shared network111.5.2 The characteristics of a switched network121.5.3 Ethernet Switches121.5.4 The working principle of switched Ethernet121.5.5 VLAN131.6 Switched Ethernet Application151.6.1, the characteristics of Gigabit Ethernet151.6.2 IEEE802.z Gigabit Ethernet standard151.6.3 IEEE802.ab Gigabit Ethernet standard161.7 Gigabit Ethernet161.7.1the technical characteristics of Gigabit Ethernet161.8 Asynchronous Transfer Mode171.8.1 ATM features171.8.2 The basic skills of ATM181.8.3 ATM interface standard181.8.4 ATM architecture181.9 Wireless LAN191.9.1 Wireless LAN Overview192、WAN202.1 Overview Overview of network interconnection network interconnection202.1.1 Applications of computer network interconnection202.1.2 Interconnection model212.1.3 Several forms of network interconnection212.1.4 Basic requirements for network interconnection212.2 Network interconnection devices222.2.1 Repeater222.2.2 Network bridge222.2.3 Router242.2.4 Gateway252.3 Routing algorithm and routing protocol262.3.1 Static and dynamic routing262.3.2 Routing algorithm262.3.3 Routing Protocol272. 4 WAN technology292.4.1 the wide area network reference model302.5 Interconnection agreements TCP / IP302.5.1 TCP / IP protocol suite312.5.2 IP network interconnection agreement32IP data packet must be submitted to the data link layer, framing package can be sent before. As supported by different networks with different maximum frame length (128-4470 bytes), generally less than IP packet, it is usually the largest IP data packets into smaller packets, and then send the packet (both above) . Packet decomposition of the larger, higher communication efficiency. Recombination is the reverse process of sub-section, it is the number of IP segments reassembled into the original IP packet. 2.6 Internet Address332.6.1 Representation and classification of IP addresses342.6.2 Subnet mask342.6.3 Specific IP address352.6.4 Address Resolution Protocol and Reverse Address Resolution Protocol362.6.5 Control Message Protocol ICMP362.6.6 UDP protocol362.6.7 TCP protocol373 Application383.1 Background383.2 Design requirements383.3 Planning and Design393.3.1 The design of network topology393.3.2 The general structure of the network403.3.3 LAN bandwidth requirements413.3.4 Cabling design principles413.3.5 Central Office Planning and Design423.3.6 Selection of network equipment433.4 Detailed design443.4.1 Flow Calculation443.4.2 Detailed Configuration453.4.3 IP address distribution463.5 References47ABSTRCTTitle Computer Network and Internet AbstractAs rapid development of computer network technology today, the use of information transmission network has become an essential way to run. With the office information and automation needs of various units to improve office efficiency, and promote information exchange, meet the requirements of modern office needs to set up business office LAN. Formation of all aspects involved in the enterprise LAN are many, first of all need a proper design and planning, then need to deal with wiring, network equipment selection and configuration, server equipment selection and configuration, network software installation, etc., which require each implementation step by step and, finally, the need for normal daily maintenance, this paper, LAN, WAN and LAN design Enterprise Brief Introduction.Keywords: LAN WAN Network Layout Switch1、LAN technology1.1 LAN Overview1.1.1 Emergence and development of local area networkLAN(Local Area Network, LAN) is a computer network, LAN is in a smaller range (an office, a building, a public works, etc.), the use of communication lines to a number of computers (usually computer) and connecting peripherals, data communication and resource sharing . LAN research began in the 20th century, 70s, 80s is the decade of the great development of local area network, LAN technology is the occurrence of 90 years of change. Ethernet is a typical representative.Now, in the world every day, thousands of local area network running, and their number far exceeds the WAN. LAN bandwidth from the 10M, 100M, 1000M, 10G, 1Tbps.1.1.2 LAN Features The three properties of the LAN1) LAN is a communications network, he only communications. It includes only the lowest two layers of OSI reference model function, so connected to the LAN data communications equipment must be added to high-level protocol and network software can be composed of computer network.2) LAN connection object is the data communications equipment, including computers, terminals, etc.3) LAN coverage is small, the transmission distance limited. LAN features1) LAN is a communications network.2) LAN connection object is the data communications equipment, including computers, terminal equipment.3) small local area network coverage.4) high transmission speed, 1Mbps 10Gbps.5) The propagation delay is small, a few milliseconds and tens of milliseconds.6) low bit error rate, 10-8.7) attributable to a single organization and management.1.1.3 LAN componentsLAN is Consists of hardware and software systems. Hardware systemHardware system is include of network servers, workstations, network interface cards, network devices, transmission media and connecting parts, and various adapters. Network SoftwareNetwork System Software (core): including network operating systems, network protocols and network communication software.Web applications: management information systems, remote education, digital libraries, etc.1.1.4 LAN Architecture and IEEE802 standardshown. System follows the IEEE 802 LAN standard ISO / OSI reference model, with a main address - the lowest two levels of physicalLayer, data link layer functions and the interface with the network layer service, high-level functions related to Internet interconnection. Data link layer is divided into two sub-layers: Logical Link Control LLC and media access control MAC (Medium Access Control) (or: media access control).1) Physical LayerAchieve bit-stream transmission and reception, creation and deletion synchronization sequence to provide the signal used, coding, and medium, provided the network topology and transmission rate.In the local area network, the signal coding is often used Manchester encoding, media are twisted pair, coaxial cable, optical fiber, multi-topology as bus, star, tree, ring; transfer rate of 1Mbps, 4 Mbps, 10 Mbps, 100 Mbps and so on.The physical layer LAN standards developed by the main content:1. Transmission medium and the corresponding distance2. Transfer rate3. Physical interface mechanical properties, electrical properties, performance characteristics and normative characteristics4. Transmit coded signals5. Error checking and synchronization signal generation and deletion6. Topology7. Physical Signaling: service primitive2) MAC sub-layer:MAC sub-layer (MAC sublayer) main function is a reasonable allocation of the channel to address the problem of channel competition and send data, the data received will be assembled on the floor with the MAC address into the fields and error detection data frame, the receiver data and complete the demolition of the frame address recognition and error control.IEEE 802 standard specifies the MAC address of 48 bits, 16 hex numbers by 12, each card has a globally unique MAC address. Manufacturers producing cards to apply to the IEEE MAC address of the first three bytes (high 24), known as the address block, after the three bytes discretionary by the manufacturer, the production network cards MAC 6 bytes address is hardcoded in the network card.3) LLC sub-layer (Logical Link Control sub-layer):Main function is to establish, maintain, sustain and release of data link, providing one or more service access points to the high-level (network layer) to provide connection-oriented and connectionless services, In addition, to ensure error-free transmission through the LAN, LLC layer also provides error control and flow control functions, it has nothing to do with the transmission medium.1.1.5 Media access control methods. Carrier Sense Multiple Access / Collision Detection (CSMA / CD)In the shared channel network, each site can determine the state of the channel. Judgement is to use the site to a receiver on from the channel receiver channel signal, and if the channel level has changed, that is, the so-called carrier, indicating that the channel by other sites occupied; if the channel level has not changed, indicating that the channel is idle.CSMA control scheme:(1) a station to be sent, first of all need to monitor the bus to determine whether there is media to send signals to other sites.(2) If the medium is idle, you can send.(3) If the medium is busy, then wait a certain interval and try again.The maximum utilization of the media depends on the length and propagation time frame. Frame longer or shorter travel time, higher utilization by the media.CD collision detection: Send data, send the side edge detection, but the conflict is detected the signal, then cancel the transfer, send a short jamming signal, to strengthen the conflict, so that all sites that conflict.CSMA / CD works:As mentioned earlier, CSMA due to carrier sense before transmission, so reducing the chance of conflict; but because of the presence of propagation delay, conflict or inevitable. As long as conflict, the channel is wasted time.CSMA / CD CSMA increase of more than one function, which is the side of sending side monitoring. Just listen to the conflict, the conflict both sides must stop sending. This channel is idle down quickly, so listen to the news site and then sent, thus increasing the channel utilization. Send this edge feature is called the conflict side listening test (Collision Detection). Shown in Figure 5.6.Strengthen Conflict: When sending the site found a conflict, in addition to immediately stop sending data, but also to continue to send several bits of human interference signal so that all users know that a conflict has occurred.CSMA / CD is used by the Ethernet medium access control.CSMA / CD to send and receive flow reading P87-88CSMA / CD protocol work process can usually be summarized as follows: first hear hair listened Development stopped the conflict random retransmissionCSMA / CD protocol features in the use of CSMA / CD bus LAN protocols, each node through the competition in the seizure of the media access rights, conflict, you must re-issued delay. Therefore, the node from the ready to send data to the success of the time to send data can not be determined, it is not suitable for transmission of real-time delay for better data. simple structure, easy network maintenance, easy to add or delete nodes, the network in the light load (fewer nodes) in the case of higher efficiency. But with the increase in the number of nodes in the network, transfer the amount of information increases, that is, in heavy load, the conflict probability increases, the performance of LAN bus will be decreased significantly. Token RingIn the Token Ring media access control method, using a token along the loop cycle. Nodes in the network can only send data when the capture token, there is no access token of the node can not send data, therefore, the use of Token Ring LAN will not conflict.Token ring access control method is based on the token, the token is a special frame (3 bytes), sent right to control the site, remove the hair after the token (as the marker for the 1,0 token), so there is no competition, it is the only media access control method.Token Ring featuresl Since each node is not a random contention channel, will not conflict, so call it is a deterministic medium access control method, and each node can send data to determine the delay time.l In the light load, because of the time waiting for the token, and less efficient.l in the heavy load on each node fairness, and efficiency.l using Token Ring LAN on each node can set different priorities, with a high-priority nodes can send data first, such as a node needs to transmit real-time data, you can apply a high priority.1.2 EthernetEthernet is based on bus-based broadcast network, it first developed in 1970, 83% of the current Ethernet network.1.2.1 the technical characteristics of the Ethernet1) Ethernet baseband network, it uses baseband transmission2) Ethernet standard IEEE802.33) The traditional type of Ethernet is a shared network, the average bandwidth of the total bandwidth / number of sites4) Ethernet bandwidth utilization is low5) Ethernet transmission technology using broadcast6) Ethernet uses Manchester coding7) Ethernet to support the transmission medium are: coaxial cable, two more lines, fiber8) Ethernet topology is the bus type and the main star9) Ethernet transmission rate is high, up to 10Gbps10) is a variable length Ethernet frames, the length of 64-1518 bytes11) Ethernet technology advanced, mature, easy expansion, easy to maintain and manage1.2.2 IEEE802.3 Ethernet architectureIEEE802.3 Ethernet architecture, including the MAC sub-layer and physical layer. Physical layer is divided into the physical signaling layer by the PLS and the PMA physical media connectors two sub-layers.1, physical layer1) The physical media connections PMA layer is responsible for signal transmission and reception bit (bit stream), and collision detection functions.2) physical signaling layer on the sending and receiving PLS bit stream Manchester encoding and decoding, and it is for the MAC sublayer to provide services it has nothing to do with the transmission media2, MAC sub-layerUse of traditional Ethernet MAC layer CSMA / CD protocol (Carrier Sense Multiple Access with Collision Detection) Carrier Sense Multiple Access / Collision Detection protocol (core agreement), the format of its data frame as shown below.1.2.3 10Mbps Ethernet10Mbps includes: 10Base-5, 10Base-2, 10Base-T and 10Base-F baseband Ethernet standard (Note: 10 indicates 10Mbps, Base, said base-band and 5 is 500 meters.)Four IEEE 802.3 specificationEthernet standard defines the physical layer of the first five for the transmission medium, and later added a 100Mbps Fast Ethernet switch, and was named 802.3u, as shown below.EthernetStandardIEEESpecificationsApprovalTimeSpeedStation /network segmentTopology StructureNetwork segment（m）Supported media10BASE-58023198310Mbps100BUS50050Coaxial cable (thick)10BASE-28023a198810Mbps30BUS18550Coaxial cable (thick)1BASE-58023c19881Mbps10/HUBStar250100 2 Category10BASE-T8023i199010MbpsHUBStar100100 2 Category10BROAD-368023b198810Mbps100Bus180075Coaxial cable 10BASE-F/F01RL8023i199210MbpsStar 500/1000/20002single-modefiber optic cable100BASE8023u199510Mbps1024Star100100+20002 Category 100 54Category100 3/4/5single-modefiberoptic cable1.3 Fast EthernetIn todays existing high-speed local area network technology, known as Fast Ethernet or 100BASE-T has become the first choice. Fast Ethernet is built on the widely accepted based on 10BASE-T Ethernet, providing the 100Mb / s for smooth, continuous network upgrades (fully compatible with, but ten times faster.)1.3.1 IEEE802.3u Fast EthernetFast Ethernet Disadvantages: loss of distance due to bring high-speed addition, it can not provide quality assurance services, and Fast Ethernet is still the shared network, so it is not suitable for use in multimedia transmission, and the more stringent requirements on delay occasions.Fast Ethernet physical media is supported by the (specific reading P99): 100BASE-TX:,Supports two pairs of five categories of unshielded twisted pair (UTP) or 2 for a class of unshielded twisted pair (STP). 1 on which to send, and 1 used for receiving, so 100Base-TX full-duplex mode can work, each node can both send and receive 100Mbps data rate. UTP using the five largest distance of 100 meters. 100BASE-T4:Support the four pairs of three types of unshielded twisted pair UTP, of which 3 used for data transmission, one pair for collision detection. Does not support full duplex communication. 100BASE-FX:Support 2 core multi-mode or single mode fiber, a core for sending, for receiving a core. 100Base-FX is mainly used for high-speed backbone network, from node to hub HUB distance can reach 450 meters.100BASE-T Fast Ethernets advantages and disadvantagesl Advantages:l higher performance, more network nodes for network bandwidth requirements or higher on the application environment;l Ethernet-based technology, with existing 10BASE-T compatible can easily migrate to high-speed networks;l maximum use of existing equipment, cabling and network management technology;l a large number of vendor support;l Disadvantages:l is still a shared Ethernet network, using CSMA / CD as the media access mode, network nodes increases, network performance will decline;l CSMA / CD network del