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To
achieve better channel utilization, employ
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sliding
window protocol:
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basic
idea: allow multiple frames to be in transit at
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one
time
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each
frame is assigned a sequence number, using k
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bits
in frame header (numbering is done module 2k)
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sender
sends up to N frames without waiting for
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ACK
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receiver
ACKs a frame by sending sequence number
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of
next frame expected, does not have to ACK every
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single
frame
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sender
maintains a list of sequence numbers that is is
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allowed
to send, receiver maintains a list of sequence
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numbers
it is prepared to accept => sliding window
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different
protocols differ in how they handle errors
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