3Com CoreBuilder 9000, Руководство пользователя

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Advantages of Using Fixed-Length Cells 309
Advantages of
Using Fixed-Length
Cells
Fixed-length cells offer the following advantages:
Network and switching queueing delays are more predictable than for
variable-length packets.
Cell switching is less complex and more reliable. ATM hardware can be
implemented more efficiently because control structures, buffers, and
buffer management schemes can be designed to known size criteria.
Cell-relay switches can process cells in parallel, achieving speeds that
far exceed the limitations of packet switch architectures.
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 containerized 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. Because
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.