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| Getting information across a network from one
computer system to another computer system involves a whole series of
operations and procedure that ensure that the information is carried without
too many problems and without significant loss of information. Problems can
arise from issues concerned with routing the information across the network,
detect and correcting errors, ensuring that information arrives in timely
fashion and in the correct order and detecting and overcoming failures. A
range of systems and protocols have been developed to deal with these issues Network
protocols are usually designed as a series of
layers, using the principle of 'divide and rule', in order to reduce complexity
at each layer and separate out functions. The OSI
basic model has seven layers which are illustrated below:
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| It would not be appropriate to
describe each of the seven layers here. Each of the seven layers provides a specific
communications service. The application layer is the layer that handles
application specific communications, that is message between open systems
specifically designed to handle interactions between applications. There are
several types of application services, such as messaging services, database
services, directory services and many other services, including management
application services. For management applications the
applications layer supports CMISE services. The related protocol is CMIP
which communicates between one open system supporting CMISE and another open
system that supports CMISE.
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| See |
ITU-T Recommendation X.200 |
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