CHAPTER 18

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  1. You can obtain the details of X.25 products from the site http://www.nationaldatamux.com.

  2. In X.25, there will be a number of packet transfers between the switches mainly for acknowledgements, flow control, and error control. Hence, the protocol overhead is very high as compared to Frame Relay, which is mainly used in optical fiber systems in which there are fewer errors.

  3. The addressing based on X.121 for a nationwide network should be done in a hierarchical fashion. X.121 address will have 14 digits, out of which 3 digits are for country code. Out of the remaining 11 digits, 2 digits can be assigned to the state, 2 digits for each district, and the remaining 7 digits for the different end systems.

  4. There are 18 PAD parameters per X.3 standard. The important parameters are baud rate, local echo mode, idle timer, line delete, line display, character editing, input flow control, and discard output.



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Principles of Digital Communication Systems and Computer Networks
Principles Digital Communication System & Computer Networks (Charles River Media Computer Engineering)
ISBN: 1584503297
EAN: 2147483647
Year: 2003
Pages: 313
Authors: K V Prasad

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