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Transcript
DCN286 INTRODUCTION TO DATA COMMUNICATION TECHNOLOGY Network Basics Introduction Instructor: Ataur Rahman [email protected] Hardware It is usually referred to physical equipment and/or components Computer usually has Input device (scanner, keyboard and mouse); Processing unit (the computer CPU); Storage Devices (RAM,ROM, Hard Drive) Output device (printer, monitor) In the computer box A computer main components are: Motherboard: or named as mainboard, everything would be put on it. CPU: the heart of the computer. Memory: show room of data access, and usually measured in MB, GB Hard drive: warehouse (storage place) of data, file and folders and usually measured in GB and TB now. Function cards: video card, sound card (or called audio card), modem, NIC (network interface card), and other extension or adaptor cards Case and power supply Computer types Server and workstation Desktop and laptop Terminal and kiosk The major manufacturers: Dell, HP, Lenovo, Apple, Acer, Toshiba, LG, Asus. Software Three major categories: Operating System: i) ii) iii) iv) Microsoft Windows XP, Vista, Win7 2003 server, 2008 server, Unix OS: Sun Solaris, IBM Unix, HP-UX Linux OS: Red Hat, SUSE, Centos, Fedora, Ubuntu Mac OS Application programs: Accounting software: Simply accounting, Accpac, Ceridian and APD payroll software, Law software: Conveyancer, PC Law, Amicus, AbacusLaw, Database: Oracle, MS SQL server, My SQL, Office software: word processing, spreadsheet and PowerPoint presentation Games and other programs Device Driver Used to communicate between hardware and OS/users. Where to get information? Personal education Online or employer offered training Friends Professionals Internet Library Manufacturer hotline Computer network Devices are connected together to share resource and exchange information. *Resources could be hardware, software, data files, pictures and video. *Exchange information could be online chatting and messaging, email, blogging and video or audio conference Networking Devices Starts from two computers Two computers can be connected directly via cross-over network cable. The cable will connect to NIC (Network Interface Card for which many people call it “network card”) of the computers. It was popular to share printer and files in the past. But, it is still practical to copy documents from your office or home desktop to your laptop. Multiple computers In your office or in our classroom, many computers will be connected together. The collective connector would be a hub, switch and router. Each computer (host) will be connected to hub/switch/router by network cable. LAN (Local Area Network): fast and reliable connect computers together. WAN (Wide Area Network): several LANs are linked via remote connection. Internet: The widest network composed by many websites of companies and organizations. Phone company and ISP Telephone service is one of the essential service offered in North America. ISP (Internet Service Provider) offer the clients access to internet. Internet access services: Rogers cable Bell or other companies DSL service Bell and/or other telecom ISDN service T1/T3 connection Dial up (less and less used now) Wireless internet access offered via cell and satellite Remote access 1. Dedicated connection (could be a physically dedicated line or a leased line) between offices 2. VPN (Virtual Private Network) VPN is a tunnel built in the high speed internet connection. The message transferred via VPN is encrypted and authenticated to protect confidentiality. 3. Modem is still used for standby remote monitor connection. Analog and digital (1) Analog: simulate the original signal from the source. It may lose the quality after repeated coping. It usually demands good connection so as to maintain the communication quality. The background noise may significantly change the information while transmitting them. Digital: interpret the information as 1 (on) and 0 (off) according to a protocol on the sender side, transmit such signal over electrical signal over lines/cables and convert those on/off electric signals back to information based on the same rules. It can tolerate low-quality transmission because relative high signals are also considered as “on” and relative low signals are treated as “off”. ASCII American Standard Code for Information Interchange is used to interpret letters, numbers and symbols into 1 and 0: Letter Binary Decimal A 01000001 65 B 01000010 66 C 01000011 67 D 01000100 68 E 01000101 69 F 01000110 70 G 01000111 71 H 01001000 72 Analog and digital (2) Dial up is to use analog phone line. ISDN and DSL are using digital phone line. Telephone itself can work on either analog or digital phone system because manufacturers offer the compatibility. Dial up must initiate connect by user. DSL would be “turned on” by ISP. TCP/IP Protocol Think the protocol as “working language over the network” TCP/IP is the industry standard and the only working protocol of internet. TCP/IP is the name of a group of protocols. Many protocols are working together in the TCP/IP family. Server/Client In general, each network device is a node and all nodes are linked by cables in the network. Sometimes, we also use terminology “host” Server: whichever host offers service to other hosts. Such as printer server, file server, web server, mail server, and ftp server. Client: whichever host receive/retrieve/use services from servers. Web server, client and browser Web server: The physical computer contains web pages of your website. It can be accessed by website name or IP address Web client: Your computer is a web client while it visits different websites. The computer will retrieve web pages from web server. Web browser: It is the program to display web page and download files such as Microsoft Internet Explorer, Firefox, Netscape, and Opera. HTTP, HTML and editor HTTP (Hypertext Transfer Protocol) is the protocol. HTML (Hypertext Markup Language) is the language to compose web pages. HTML editor is the program to compose webpage in HTML. It could be notepad, MS Word, Frontpage, Dreamweaver, Homesite, HTML Editor. Multimedia and plug-in Flash player, Adobe reader and shockwave player are examples of application programs to display/play various format files. Plug-in is that the program would be running “embedded” in another main program. Domain Name Domain name is identification name in internet. It has a tree branch structure. Its format is sub_domain.2nd_level_domain_name.1st_level_ domain_name.top_level_domain_name such as support.office.microsoft.com Top level domain name: Traditional .org, .com, .net, .gov, .edu, Country code: .ca, .uk, .jp, .it New name: .asia, .lib, .info, .jobs, .museum Hostname is the computer or equipment name. FQDN (Full Qualified Domain Name) will be the combination of the host name and domain name TCP/IP model Application Application Presentation Session Transport Transport Internet Network Network Interface Data Link Physical MAC address and IP address MAC address: It is also called physical address. It is “burned” on the NIC by the manufacturer and usually cannot be changed. Its format is 48 bits and usually displayed in hex such as 00-5056-C0-00-01. IP address: It is also called logical address as it is assigned by network administrator or user. IP V4 is the main protocol in North America and its formation is presented as 192.168.2.200. IP address is used to identify hosts in the network. IP address 1. Traditionally, the IP address was classified in classes: Class A: network 1 – 126 (Network 127 is reserved for loopback and internal testing) Class B: network 128 – 191 Class C: network 192 – 223 Class D: network 224 - 239 (Reserved for multicast) Class E: network 240 – 255(Reserved for Experimental, used for research) 2. There are public IP address used in Internet and private IP address used in company/organization internal networks. Class A: 10.0.0.0 -10.255.255.255 Class B: 172.16.0.0 – 172.31.255.255 Class C: 192.168.0.0 – 192.168.255.255 Routing If all traffics are in the same LAN (subnet), no routing is required. The computers talk to each other over network cable directly. In different LAN (subnet), the packet sent from sender must be “redirected” (routed) to another network in which the recipient is located. Useful commands Ipconfig Ping Tracert Nslookup Shutdown Help Troubleshooting procedures 1. Know the facts and collect background information 2. Isolate the problem affected range 3. Document with time stamp 4. Start diagnose 5. Prepare solutions and try simple one first. (Over thinking will waste your time and over-correction may disable whole network). Bit, Byte, KB, MB, GB and TB Computer is working with electrical components. It does not understand human language. It would translate all characters, numbers and symbols into signal of 1 (on or high) and 0 (off or low). Bit is the signal unit with value of 1 or 0. Byte is 8 bits KB is 1000 (in fact, 1,024) Byte MB = 1000 (in fact, 1,024) KB GB is 1000 (in fact, 1,024) MB TB = 1000 (in fact, 1,024) GB Network math Decimal (base 10) numbering system Hexadecimal (base 16) numbering system Binary (base 2) numbering system 0 0 0 1 1 1 2 2 10 3 3 11 4 4 100 5 5 101 6 6 110 7 7 111 8 8 1000 9 9 1001 10 a 1010 11 b 1011 12 c 1100 13 d 1101 14 e 1110 15 f 1111 16 10 10000 Binary convert to Decimal (1) Binary value: 00000000001 00000000010 00000000100 00000001000 00000010000 00000100000 00001000000 00010000000 00100000000 01000000000 10000000000 Pre-list following: 2^0 = 1 2^1 = 2 2^2 = 4 2^3 = 8 2^4 = 16 2^5 = 32 2^6 = 64 2^7 = 128 2^8 = 256 2^9 = 512 2^10 = 1024 Converting Decimal numbers to 8-bit Binary Numbers Conversion Exercise Use the example below to convert the decimal Number 168 to a binary: 128 fits into 168, so the left most bit in the binary number is a 1, 168 – 128 leaves 40. 64 does not fit into 40, so the second bit in from the left is a 0. 32 fits into 40, so the third bit in from the left is a 1, 40 – 32 leaves 8. 16 does not fit into 8 so the forth bit in from the left is a 0. 8 fits into 8, so the fifth bit in from the left is a 1, 8 – 8 leaves 0, so the remaining bits to the right are all 0. Result: Decimal 168 = 10101000 Pre-list : 2^0 = 1 2^1 = 2 2^2 = 4 2^3 = 8 2^4 = 16 2^5 = 32 2^6 = 64 2^7 = 128 2^8 = 256 2^9 = 512 2^10 =1024 2^11 =2048 Convert binary to decimal From the “1”’s position, pick up corresponding decimal number value and add all together. Let’s calculate 101101101111: The first “1” has 11 numbers at right hand and it means 2^11=2048. The next 1 has 9 numbers on right hand and it is 2^9=512 …… ….. Add up all: 2048+512+256+64+32+8+4+2+1=2927 Thus, 101101101111 2927 Pre-list : 2^0 = 1 2^1 = 2 2^2 = 4 2^3 = 8 2^4 = 16 2^5 = 32 2^6 = 64 2^7 = 128 2^8 = 256 2^9 = 512 2^10 =1024 2^11 =2048 Boolean calculation 1 means true 0 means false Subnet Mask Subnet mask is to divided IP address into two sections: network ID and host ID. Say the IP address is 192.168.4.64 with subnet mask 255.255.255.0: Translate all decimal into binary: IP address would be 11000000.100101000.00000100.01000000 Subnet mask would be 11111111.11111111.11111111.00000000 Final result: Network id: 11000000.100101000.00000100 which equals to 192.168.4 Host id: 01000000 meaning 64 Valid subnet mask value 0 00000000 128 10000000 192 11000000 224 11100000 240 11110000 248 11111000 252 11111100 254 11111110 255 11111111 Question Any question? If you do not have question, please practice conversion calculation between binary and decimal numbering system. 1. Please convert decimal value 123, 240 and 255 to 8 bits binary. 2. Please convert binary value 11001101, 10010011 and 00110011 into decimal value.