Communication Tasks

Communication Tasks Some key tasks that must be performed in a data communication system these elements can be added, deleted, or merged together  Transmission System Utilization                              Interfacing Signal Generation                                                      Synchronization Exchange Management                                              Error Detection and Correction Flow Control                                                              Addressing Routing                                                                       Recovery Security                                                                       Network Management

™   Transmission System Utilization For efficient use of Transmission facilities that are shared among a number of communicating devices ™   Interfacing A  device  must  have  an  Interface  with  the  Transmission  System/Transmission Medium ™   Signal Generation Once  an  interface  is established than Electromagnetic  Signals  travel  over  Transmission  Medium.       Properties of Signals    Capable of being propagated over TX. Medium    Interpretable as data at the Receiver ™   Synchronization Before the transmission , the    transmission    and    the    reception    should    be    properly                            synchronized. Synchronization  means  that both  the  receiver / sender   must  be  able  to  determine,            when  to expect a new transmission and when to send acknowledgement. .   ™   Exchange Management When  data  needs  to  be  exchanged  in  both  directions  over  a  period  of  time,  both parties must cooperate as below:-    Whether both devices must transmit simultaneously or take turns    Amount of Data to be sent at one time    Format f the Data    What to do when an Error Arises ™   Error Detection and Correction In all communication  Systems, there is a potential risk for errors and impairments. Signals  are  distorted  to  some  extent  before  reaching  their  destination.  Error Detection & Correction needs to be employed in Data Processing Systems where a change in say the contents of a file cannot be tolerated ™   Flow Control To make sure that source does not overwhelm destination by sending data faster than it can be handled and processed ™   Addressing & Routing If TX facility is shared by two or more devices, source must specify the identity or the address of the destination system and if Tx. System is itself a system, a proper route  must  be  allocated  that  the  data  will  take  in  order  to  reach  the  desired destination ™   Recovery If  a  data  transmission  is  interrupted  due  to  a  fault  somewhere  in  the  system, recovery  techniques  are  needed.  The  objective  is  either  to  resume  activity  at  the point of interruption and to restore the state of the system to what it was prior to the interruption ™   Security Security  is  very  important  issue  in  a  Data  Communication  System.  The  sender needs to be assured that    Only the Intended receiver receives the data    Data is delivered unaltered