Communication Network Protocols Abinashi Dhungel

Outline Part 1 : Protocol Suite  OSI Protocol Suite  TCP / IP Protocol Suite Part 2: Recent Advances Part 3 : Future Development

Communication Network Protocols Rules and standards  Regulate the exchange of messages  Reliable and orderly flow of information among processes Communication Services  Connection oriented Reliable and in sequence  Mechanism to acknowledge the receipt of a package  Virtual Circuit (Network) / Circuit Switching (Hardware)‏  Connectionless Unreliable and best effort basis  May arrive at arbitrary order  Datagram (Network) / Packet Switching (Hardware)‏

Communication Hardware and Software  Design structured in layers  Services – set of operations a layer provide to layer above it through interface.  Peers - Corresponding entities in same layer  Protocol – set of rules defining how message or packets are exchanged between peers. Layer k Protocol Layer k + 1 Layer k - 1 Service provided by layer k

Network system architecture  Series of layers and their protocols  Protocol suite OSI TCP / IP OSI  Protocols rarely used / General / Still Valid TCP / IP  Model not used / Protocols widely used [Tanenbaum 2002]

OSI Protocol Suite

Physical Layer  Transmission of Raw bit over communication channel  Mechanical, electrical, timing interface, physical transmission medium. Data Link Layer  Ensures the reliable data transfer of frames Group of bits (few hundred to few thousand bytes [Tanenbaum 2002])‏  Configuration, Error control, sequencing, flow control of frames  Medium Access Control (MAC) sublayer

Network Layer  Sending Packets (Basic unit of data transfers in network layer)‏  Routing, Error and Flow control between nodes  Virtual Circuit Routing decision at connection In-order delivery  Datagram Routing decision packet-by-packet basis Requires reassembly of packets

Transport Layer  End-to-end layer  Interface between communication subnetwork  (Physical, data link and network layers)‏ Network independent layer  (session, presentation, and application)‏  Breaks message into packets, sends to network layer

Session, Presentation, & Application Layers  Session Establish session between machines  Dialog control (whose turn to transmit)‏  Token management (preventing two parties from same critical operation at the same time)‏  Synchronization  Presentation Data Encryption, compression and code conversion  Computers with different data representation can communicate  Application Left to the designer of application  Egs. HTTP, File transfer,

TCP / IP

Internet Layer  Inject packets into any network Packets travel independently to destination Might arrive in different order  IP (internet protocol)‏ Deliver IP packets, routing, congestion control  (similar to OSI network layer) Transport Layer  Transport protocols TCP  Reliable, Connection oriented  Bytestream into discrete messages, flow control UDP  Unreliable, connectionless protocol  (prompt delivery than accurate delivery)‏

Application Layer  TELNET Virtual terminal  FTP, SMPT, DNS

Recent Advances Despite the maturity of Communication Networks Protocols like TCP / IP, many application specific protocols are used today [Clare, Agre, Yan 01]. Extensions on TCP in the satellite environment to effectively utilize the available capacity of the network path in satellite channels [Allman, Glover 99]. Traditional TCP/IP implementations have required far too much resources both in terms of code size and memory usage to be useful in small 8 or 16-bit systems [ Dunkels 03 ]. Implemented two small generic and portable TCP/IP implementations, lwIP (lightweight IP) and uIP (micro IP), for 8 and 16 - bit microcontrollers [ Dunkels 03 ].

Recent Advances IP version 6 (IPv6) is a new version of the Internet Protocol, designed as the successor to IP version 4 (IPv4).  Expanded Addressing Capabilities - increases the IP address size from 32 bits to 128 bits, to support more levels of addressing hierarchy, a much greater number of addressable nodes [Deering, Hinden 98]. IPv6 prevalance is still low but growing at smaller rate [Gunderson 08]. Deployment - Russia (0.76%), France (0.65%), Ukraine (0.64%), Norway (0.49%), and the United States (0.45%). Absolute deployment numbers, higher in China but relative number low 0.24% [Gunderson 08]. IPv6 has been implemented on all major operating systems in use in commercial, business, and home consumer environments. Mac OS X led in IPv6 penetration of 2.44%, followed by Linux (0.93%) and and and Windows Vista (0.32%) [Gunderson 08].

Future Development More device support  Ubiquitous Computing  Ambient Computing

References [Allman, Glover 99], “Enhancing TCP Over Satellite Channels using Standard Mechanisms”, Internet Society IETF Network Working Group RFC 2488, January 1999 [Clare, Agre, Yan 01] Clare, L.P., Agre, J.R., Tsun-Yee Yan, “ IEEE Proceedings on Aerospace Conference, 2001”, Volume 2, March 2001 Page(s):2/943 – 2/950 [Dunkels 03] A. Dunkels, “Full TCP/IP for 8-bit architectures”, Proceedings of the First International Conference on Mobile Systems Applications and Services (MobiSys-03), San Francisco, CA, USA, 2003, pp [Deering, Hinden 98] S. Deering, R. Hinden, “Internet Protocol, Version 6 (IPv6) Specification”, Internet Society IETF Network Working Group RFC 2460, December 1998 [Gunderson 08] Steinar H. Gunderson, "Global IPv6 statistics - Measuring the current state of IPv6 for ordinary users", Réseaux IP Européens, October 2008 [Tanenbaum 02] “Computer Networks”, 4 th Edition, Andrew S. Tanenbaum, Prentice Hall, 2002

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