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Even though the ISO model of n

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Even though the ISO model of networking specifies seven layers of functionality,most computer systems use fewer lay ers to implement a network.Why do they use fewer layers? What problems could the use of fewer layers cause?

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林呼

A certain network layered-protocol may achieve the same functionality of the ISO in fewer layers by using one layer to implement functionality provided in two(or possibly more) layers in the 190
model.Other models may decide there is no need for certain layers in the ISO model For example,the presentation and session layers are absent in the TCP/ IP protocol.Another reason may be that certain layers specified in the ISO model do not apply to a certain implementation.Let's use TCP /IP again as an example where no data-link or physical layer is specified by the model.The thinking behind TC P /IP is that the functionality behind the data link and physical layers is not pertinent to TC P 'IP- it merely assumes some network connection is provided-whetheritbe Ethernet,wireless,token ring etc.
A potential problem with implementing fewer layers is that certain functionality may not be provided by features specified in the omitted layers

发表于 2018-03-25 10:18:49 回复(0)