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Comprehensive Overview of Computer Networking Standards and Protocols

This revision document covers essential topics in computer networks, including standards like OSI and TCP/IP, LANs, MANs, and WANs. It delves into wireless LAN technologies, data compression methods, error detection and correction techniques, routing, and network management. Additionally, it highlights the OSI reference model's seven-layer structure, functions of each layer, and the relationship with various networking standards. Key protocols, including IEEE802.x and ATM, are discussed, alongside modern networking technologies like GPS and 3G systems. This resource is vital for understanding the complexities of contemporary networking.

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Comprehensive Overview of Computer Networking Standards and Protocols

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  1. CCM4010 - Revision • Introduction, computer networks, standards, OSI, TCP/IP, LANs, MANs, WANs • Wireless LANs • Data Compression • Error Detection/Correction • Routing • Network Management • Network Security

  2. OSI Reference Model • Seven layered structure • Application • Presentation • Session • Transport • Network • Data Link • Physical

  3. OSIRM • Functions of each layer • Relationships between various networking standards and the OSIRM • LAN standards • IEEE802.x • FDDI • DQDB • ATM • etc.

  4. Protocols Protocol is the set of rules that make communication more efficient.

  5. LANs/MANs/WANs • IEEE802.11 – wireless LAN • HiperLAN - wireless LAN (Europe) • IEEE802.x – LANs • 10Base2/10Base5/10Base T/100Base T etc. • ATM • DQDB • FDDI – SAS/DAS • SDH/SONET • Selection criteria

  6. LANs/MANs/WANs • Topologies • LAN • Bus • Token ring • Star • Extended star

  7. Wireless LANs and Mobile Systems • Infrastructure • Ad-hoc • WAP • i-mode • UMTS • Location technology: • Global Positioning System (GPS)

  8. Transmission Media and supporting technologies • ISDN • ADSL • PSTN • Satellite link • Data link using mobile telephony • Microwave • The Internet

  9. Delay calculations • Propagation time = distance/speed • Transmission time = Number of bits in a frame/bit rate • Total time = outward propagation time + outward transmission time + inward propagation time + inward transmission time

  10. Bridges/Routers • Use of bridges • Routing • Routing tables • Adaptive routing • Non-adaptive routing

  11. Data Compression • Packed decimal • Relative encoding • Character suppression • Huffman coding • Static • dynamic • Limpel-Zev coding

  12. Huffman coding • Statistical encoding • Analyse the characters to be transmitted • Determine character types and their relative frequency • Create an unbalanced tree (Huffman code tree/ binary tree) • Obtain codeword for each character • Calculate the number of bits needed to transmit these characters • Calculate the average number of bits per codeword needed to transmit these characters

  13. Huffman coding • Example: • “AGAIN AND AGAIN AND AGAIN” • Determine character types and their relative frequency A 8; N 5; Sp 4; G 3; I 3; D 2. Total 25 • Create an unbalanced tree (Huffman code tree/ binary tree) • Obtain codeword for each character A 00; N 11; Sp 010; G 011; I 100; D 101 • Calculate the number of bits needed to transmit these characters Total bits 62 • Calculate the average number of bits per codeword needed to transmit these characters 62/25 = 2.48 b/character

  14. Limpel-Zev Coding • Example: • “AGAIN AND AGAIN AND AGAIN” • Ad a space to make the number of characters even (26) • “AGAIN AND AGAIN AND AGAIN ” • Take pair of characters together and determine their frequency AG 3; AI 3; NSp 3; AN 2; DSp 2; Total 13 • Create binary tree • Obtain codeword for each character AG 11; AI 00; NSp 01; AN 100; DSp 101 • Calculate the number of bits needed to transmit these characters Total bits 30

  15. Compression • A very simple stratagem applied to the string could reduce the number of bits needed for transmission of the string still further. Suggest and validate, a suitable stratagem • Answer Put the extra space at the beginning of the string. There are now only four pairs and the total number of bits is 26. SpA; GA; IN; ND;

  16. Huffman - decoding • A code table must be available • Read data as received, compare to known codes, • if it is a match, identify code, • if not keep reading and concatenating bits received

  17. Huffman - decoding • Example 001101000000010110011010011010001 Character coding: E = 1; T = 01; G = 001; C = 0000; A = 0001 001 1 01 0000 0001 01 1 001 1 01 001 1 01 0001 G E T C A T E G E T G E T A

  18. Error control • ASCII • Parity bit: additional bit added to each character • Even parity • Total number of bits (inclusive) in a digital word is even; e.g. 10110111 • Odd parity • Total number of bits (inclusive) in a digital word is odd; e.g. 10110110

  19. Error control • Hamming distance: The Hamming distance of the code is the minimum number of bit positions in which two valid codewords differ. 00000000 00000011 00000101 00000110 Hamming distance? Odd/even parity?

  20. Hamming Codes • The parity bits are inserted into the positions which numerically are the powers of 2 (i.e. 1,2,4,8,16 etc.) • Parity bit 1 covers bits 1,3,5,7,9,… • Parity bit 2 covers bits 2,3,6,7,10,11,14,15,.. • Parity bit 4 covers bits 4,5,6,7,12,13,14,15,20,21,22,23,… • Parity bit 8 covers bits 8,9,10,11,12,13,14,15,24,25,26,27,28,29,30,31,…

  21. Network Management • Functions • Fault management • Performance management • Security • Accounting • etc. • Characteristics of network managers • Other network management topics

  22. Network Security • Terminology/definitions • Solutions

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