Transcript Lecture04
Information Science Institute of Sripatum University IS516 Computer Communication and Networks ื่ สารคอมพิวเตอร์และเครือข่าย การสอ Asst.Dr.Surasak Mungsing [email protected] [email protected] http://www.spu.ac.th/teacher/surasak.mu Sripatum University 1 SPU Lecture 04 Networking Devices and Software 2 LAN: Local Area Network 3 Information Science Institute of Sripatum University Local Area Network Star Network Ring Network Bus Network 4 SPU Information Science Institute of Sripatum University Tiered Local Area Networks 5 SPU Information Science Institute of Sripatum University Single-Cell Wireless LAN 6 SPU Information Science Institute of Sripatum University Multiple-Cell Wireless LAN 7 SPU Information Science Institute of Sripatum University Wireless LAN Configurations 8 SPU Media 9 Information Science Institute of Sripatum University Electromagnetic Spectrum for Telecommunication ELF - Elementary Low Frequency VF - Voice Frequency VLF - Very Low Frequency LF - Low Frequency MF - Medium Frequency HF - High Frequency VHF - Very High Frequency UHF - Ultrahigh Frequency SHF - Superhigh Frequency EHF - Extremely Frequency 10 SPU Information Science Institute of Sripatum University Comparison of Shielded and Unshielded Twisted Pair Attenuation (dB per 100m) Frequency (MHz) Category 3 UTP Category 5 UTP 1 2.6 4 Near-end Crosstalk(dB) STP Category 3 UTP Category 5 UTP STP 2.0 1.1 41 62 58 5.6 4.1 2.2 32 53 58 16 13.1 8.2 4.4 23 44 50.4 25 - 10.4 6.2 - 41 47.5 100 - 22.0 12.3 - 32 38.5 300 - - 21.4 - - 31.3 11 SPU Information Science Institute of Sripatum University Twisted Pair Categories and Classes 12 SPU Information Science Institute of Sripatum University Structured Cabling Elements 13 SPU Information Science Institute of Sripatum University Cable Distances Specified in EIA-568-A Telecommunications D Outlet Main A Horizontal Cross-connect Cross-connect Telecommunications D Outlet C Horizontal B Cross-connect Media Type UTP (Voice Transmission Intermediate Cross-connect A B C D 900 m 500 m 300 m 90 m Category 3 UTP up to 16 MHz 90 m 90 m 90 m 90 m Category 5 UTP up to 100 MHz 90 m 90 m 90 m 90 m STP up to 300 MHz 90 m 90 m 90 m 90 m 02.5 mm Optical Fiber 2000 m 500 m 1500 m 90 m Single-mode Optical Fiber 3000 m 500 m 2500 m 90 m 14 SPU Information Science Institute of Sripatum University IEEE 802 Protocol Models Compared to OSI Model 15 SPU Information Science Institute of Sripatum University LAN Protocol in Context 16 SPU Information Science Institute of Sripatum University LLC PDU in a MAC Frame 17 SPU Internetworking Devices 18 Information Science Institute of Sripatum University Internetworking Devices When two or more computers connect in order to communicate to each other or to use shared resources, they are a computer network When two or more networks connect for communication or resource sharing purpose, they are an internetwork or internet Connecting two or more networks requires networking device(s) such as Repeater, Bridges, Switches, Routers, Gateway 19 SPU Information Science Institute of Sripatum University OSI VS Internetworking Devices Each networking device communicates with network layers in the OSI reference model Lower layers of the OSI reference model describe functionalities of main networking device and type of device classified by network layer of the OSI Devices in physical layer, e.g. MODEM, Hub, PBX, repeater Devices in data link layer, e.g. Bridge, Switch Devices in network layer, e.g. Router Devices in network layer, e.g. Gateway 20 SPU Information Science Institute of Sripatum University Internetworking Devices and the OSI Model 21 SPU Information Science Institute of Sripatum University MODEM : MOdulation and DEModulation Main functions of a MODEM are to convert analog signal to digital signal and to digital signal to convert analog signal Signals used in telephone network are analog but Signals used in computers are digital 22 SPU Information Science Institute of Sripatum University Dial-up line and a Dedicated line Dial-up line is temporary connection using telephone line for communications Dedicated line is line always connected between two communications devices Advantages of dial-up line Advantages of dedicated line 1. Costs no more than making regular call 1. Quality and consistency of connection are better 2. Computers at any two locations can establish a connection using modems and telephone network 2. Computer locations are fixed 3. Can be digital or analog 23 SPU Information Science Institute of Sripatum University HUB A device that broadcasts signals. Normally used to expand network as tree structure topology based on 10Base-T standard Main responsibility of a hub is to broadcast signals through or within a network, therefore it is a physical layer device of the OSI reference model Today’s hub can manage ports and evolved to switched hub, which support layer 2 and layer 3 functions 24 SPU Information Science Institute of Sripatum University Switched Hub N 10 10 Mbps Mbps 10 A x 10Mbps Mbps B 10 Mbps C D 25 SPU Information Science Institute of Sripatum University Repeater An electronic device that only works in the physical layer of the OSI reference model Used to repeat and amplify signals so that they can travel farther, which solved attenuation problem Repeater dose not change or modify signals, it just repeats and retransmit the signals, therefore it joins two portions of the same network to become one larger network 26 SPU Information Science Institute of Sripatum University A Repeater in the OSI Model 27 SPU Information Science Institute of Sripatum University Repeater does not change but retransmit signals to another segment of the network makes two segments become one network 28 SPU Information Science Institute of Sripatum University Bridge A device than link same type of networks, such as Ethernet to Ethernet, or token ring to token ring Broadcasting signals within same network if destination address is in other network, there will be no broadcasting within the sender network, and packets will be send to bridge and then to the other network 29 SPU Information Science Institute of Sripatum University A Bridge in the OSI Model 30 SPU Information Science Institute of Sripatum University A Bridge 31 SPU Information Science Institute of Sripatum University Switch • • Many types of switches: Cell switch or ATM switch, Ethernet switch, frame relay Switching devices are developed with new technology and capable of transmitting and receiving data at very high speed (many hundred million bits per second), such as frame relay and ATM switch 32 SPU Information Science Institute of Sripatum University Router • • • A device that connects networks, such as Ethernet, frame relay (LAN-to-WAN) with specific protocols to be used by routers Router receives packets and examines destination of each packet then compare with routing table to choose a route and forward the packet via that route If the forward route uses different network standard it then transform to the new standard 33 SPU Information Science Institute of Sripatum University A Router in the OSI Model 34 SPU Information Science Institute of Sripatum University Routers in an internet 35 SPU Information Science Institute of Sripatum University Gateway Device or software for connecting networks, same or different type of networks If networks use different protocols, gateway acts as a protocol converter so that they can communicate Supports from application layer downward Facilitates distributed applications 36 SPU Information Science Institute of Sripatum University A Gateway in the OSI Model 37 SPU Information Science Institute of Sripatum University A Gateway 38 SPU Communication software 39 Information Science Institute of Sripatum University Communication Software Software that connects and exchanges data between communication system in a network, e.g. Telnet, FTP (File Transfer Protocol), Web Browser (IE/Netscape…), E-Mail, Instant Messaging and Internet Telephony 40 SPU Information Science Institute of Sripatum University Telnet Service software for remote login telnet can run on Windows OS by using “run” menu and type telnet <ip address > for example telnet 202.44.68.3 or specifies the domain name to be connected, such as telnet spu.ac.th 41 SPU Information Science Institute of Sripatum University Telnet Type telnet 202.44.68.3 Enter username and password display after successfully connected to spu.ac.th 42 SPU Information Science Institute of Sripatum University Benefit of Telnet using resources of a remote computer Searching and transfering data between computers, even in different system Checking e-Mails or other services in case of using other computer, in particular, in text mode 43 SPU Information Science Institute of Sripatum University FTP (File Transfer Protocol) Use for file transfer between computers, within same network or different network, and same type or different type of computers FTP programs that work in text mode require typing and those that work in Graphic mode are easier to use 44 SPU Information Science Institute of Sripatum University Instant Messaging : ICQ, MSN 1: Login to the IM server 2: Server checks if any established friends, family, or co-workers, called buddies, are online 3: Send instant messages to online buddy Step Step 2 1 IM server 4: Instant message travels through messaging server and then to online buddy Step messaging 3 server Step 4 45 SPU Information Science Institute of Sripatum University Next Lecture: Guided Networks 46 SPU