.3gpp.org/DynaReport/36-series.htm,accessed 23 September 2014. [15] ITU. G.99x Series for DSL Standards. http://www.itu.int/rec/T-REC-G/en, accessed 23 September 2014. Packetised Data Communications Preview Questions What is packet switching? What information is required to deliver a data packet? What are protocols of data communications? How do different layers interact? How did the packet-switched communications standard come about? What are the performance measures for evaluating a data communications system? Learning Objectives Packet-switched data communications History of the Internet Internet telecommunications technologies Queuing performance metrics Internet protocols Historical Note Internet development traces its roots back to the 1950s and the emergence of main-frame computers. Early computers (pictured) were stand-alone machines and did not have the means to communicate with other machines: commands, programming and data storage and transfer Broadband Telecommunications Technologies and Management, First Edition. Riaz Esmailzadeh. C 2016 Riaz Esmailzadeh. Published 2016 by John Wiley & Sons, Ltd. Companion Website: www.wiley.com/go/BTTM Broadband Telecommunications Technologies and Management were carried out manually using magnetic tapes (pictured) [1] or punch cards (pictured). 1 As the usage of computers in business and government applications grew, interactions between computers, and between computers and network terminals became necessary. Clearly there was a need for a theoretical framework and network equipment to support computer commu- nications, which needed to be developed. On the theoretical side, while voice traffic charac- teristics were well researched, no such information existed for computer communications traffic. Voice ######### traffic models show the average and variance of a telephone call: a voice call could be expected to last a certain length of time with a certain statistical behaviour. Moreover, the bandwidth necessary to support a voice call is fixed - 4 kHz, and given a n