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1、網路與通信協定陳彥錚 (Yen-Cheng Chen) ycchenncnu.edu.tw http:/www.ncnu.edu.tw/ycchen/內容大綱o1. 網路基本認識o2. OSI 7層參考模型o3. Internet 通信協定集o4. 網路設備o5. 網管相關通信協定1. 網路基本認識o網路分類o網路技術o網路傳輸介質o網路設備網路分類o網路 - 依終端應用區分n數據通信網路 (Data Communication Network)n電信網路 (Telecommunication Network)o網路 - 依距離區分nLAN (Local Area Network)nMAN (
2、Metropolitan Area Network)nWAN (Wide Area Network)網路分類 (續)o網路 - 依交換方式n線路交換 (Circuit Switching)n分封交換 (Packet Switching)o網路 - 依傳輸介質o有線網路 (Wired Network)o無線網路 (Wireless Network)ATMATM網路技術LANLANMANMANWANWANEthernetEthernet Token RingToken RingGigabitGigabit EthernetEthernetISDN (basic rate)ISDN (basic r
3、ate)FDDIFDDIFastFast EthernetEthernetFrame RelayFrame RelayMAN it is used strictly for signal propagation.HuboOperates at Layer 1, the physical layer. oSimply a multiport repeater.oCan be used to increase overall network size and number of nodes on a single segment. oCan isolate faults within the su
4、bnet.oAllows you to add stations to a segment without disrupting the entire network.BridgeoOperates at Layer 2, the data link layer. oAllows networks with different physical signaling, but with compatible data link addressing schemes, to communicate. oHelps reduce traffic on a backbone LAN by filter
5、ing any information coming from one segment to another that does not need to be forwarded through the backbone. oA common use for a bridge is to allow users on an Ethernet LAN and a Token Ring LAN to communicate with each other.Bridge ExampleApplicationApplicationPresentationPresentationSessionSessi
6、onTransportTransportPhysicalPhysicalNetworkNetworkData LinkData LinkApplicationApplicationPhysicalPhysicalPresentationPresentationSessionSessionTransportTransportNetworkNetworkData LinkData LinkPhysicalPhysicalData LinkData LinkPhysicalPhysicalData LinkData LinkBridgeBridgeSwitchoOperates at Layer 2
7、, the data link layer. oDispatches data to its destination, which it determines from the packets lower-layer media access control (MAC) address.oCan limit traffic, and does not understand network protocols. RouteroOperates at Layer 3, the network layer. oConnects two networks with different technolo
8、gies, and provides an intelligent means of transferring packets from one network to the other.oAlso forwards traffic among multiple hubs and bridges. Router ExampleApplicationApplicationPresentationPresentationSessionSessionTransportTransportPhysicalPhysicalNetworkNetworkData LinkData LinkApplicatio
9、nApplicationPhysicalPhysicalPresentationPresentationSessionSessionTransportTransportNetworkNetworkData LinkData LinkPhysicalPhysicalNetworkNetworkData LinkData LinkPhysicalPhysicalNetworkNetworkData LinkData LinkRouterRouterRouting SwitchoOperates at Layer 3, the network layer.oCombines the intellig
10、ence of a router with the efficiency of a switch, oRouting data at higher speeds.GatewayoOperates at Layer 7, the application layer.oCan encompass all seven of the OSI model layers. oA computing system that can be programmed to do any number of intricate protocol conversions and negotiations, such a
11、s between IP and IPX.5. 網管相關通信協定oSNMPv1oSNMPv2CoICMPoARP/RARPoDHCPSNMPv1 (Simple Network Management Protocol version 1)FThe most common management protocol in use in data networks. FProvides a means of obtaining information from, and sending information to, network devices. FBased on the manager-age
12、nt model. FUses Management Information Bases (MIBs) to exchange information between the manager and the agent. FUsing the SNMP protocol, a manager can query and modify the status and configuration information on each managed device by making requests to the agent running on the managed device. FAll
13、commands use the UDP/IP protocol, which means that communication between the manager and the agent is connectionless. FSNMP operates at Layer 7, the application layer.SNMPv2C (version 2)FSNMPv2C includes the basic functions of SNMPv1. FAdds w new message types, w standardized multi-protocol support,
14、 w enhanced security, w new MIB objects, and w a way to co-exist with SNMPv1. FSNMPv2C is useful for the retrieval of large amounts of management information using fewer network resources.ICMP (Internet Control Message Protocol)FICMP is the part of IP that handles error and control messages. FICMP o
15、perates at Layer 3, the network layer. FICMP supports an echo function, which sends a packet on a round-trip between two hosts. FPing, which sends a signal to see if an interface is up and running, is based on ICMP echo. FICMP can also send an address mask request that returns the address of the sub
16、net mask on the remote system. This feature is important for non-SNMP devices.ICMP TypeEcho Request / Echo Reply Destination Unreachable Source Quench Redirect Time Exceeded Parameter Problem Timestamp Request / Timestamp Reply Address Mask Request / Address Mask Reply8 / 0345111213 / 1417 / 18PingMost basic tool for internet managementBased on ICMP ECHO_REQUEST messageAvailable on all TCP/IP stacksUseful for measuring ConnectivityPacket
