3Com CoreBuilder 7000, Operation Manual

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ATM Layers 21
Having all data in a fixed-length cell format speeds transmission
dramatically by eliminating the need for protocol recognition and
decoding. A good analogy is containerised shipping where uniform
shape and weight of containers and standardized labelling
considerably ease and quicken processing.
The cell format also allows for multi-protocol transmissions. Since ATM
is protocol transparent, the various protocols can be transferred at the
same time. With ATM, the same connection can be used for phone, fax,
video, data and other information simultaneously. This multiprotocol
advantage also offers scalability, greatly reducing the configuration
changes necessary for adding a new traffic type to your network.
ATM Layers
As in the OSI model, ATM has levels that are used to divide the functions
of ATM.
Figure 2 shows the OSI and ATM models, side by side. Note that the ATM
layers do not exactly match the OSI layers.
Figure 2 OSI and ATM Layers
ATM Adaptation Layer
ATM Layer
Physical Layer
Network Layer
Datalink Layer
Physical Layer
Transport Layer
ATM Layers OSI Layers