| DESCRIPTION |
This is a sliding window protocol using a logitudinal parity check checksum.
than the 3BSCP protocol.
Like 3BSCP protocol, SWP (Sliding Window Protocol) tries to take advantage
of response time over the network by sending lines without waiting for
acknowledgements. SWP will increase the number of lines that it will send
without acknowledgement to a maximum if the connection seems successful and
will reduce the number of lines in a 'window' to as few as 1 if there seems
to be a lot of errors. Each line has its own checksum. Each line is
acknowledged. Under ideal circumstances, it is therefore more resource
intensive than 3BSCP. However, when errors occur, SWP only resends lines
It is comparable in speed to the 3BSCP protocol, but is a bit slower and
that were not acknowledged (1 for each error), while 3BSCP must resend an
entire block (100 the 1st error, 50 lines the 2nd...). 3BSCP also quits
when a maximum number of errors is sensed, while SWP does not quit unless it senses that the virtual connection has been terminated.
'SWP' CAN NOT BE USED WITH VERSIONS OF MAILMAN PRIOR TO 3.17a !!!
more likely to succeed. Speed reported is based on actual lines sent.
Characters (lines) resent because of errors are not included in the total as
they are in the 3BSCP protocol. Error recovery is much better. Short of
the virtual connection almost totally disintegrating, messages sent with
this protocol will be transmitted. While the 3BSCP protocol must resend an
entire block when it gets an error, this protocol sends only lines that were
not acknowledged. It is therefore faster under non-ideal circumstances
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