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PK-88 OPERATING MANUAL
MAXFRAME 'n'
Parameters:
'n' -
1 to 7 specifies a number of packet frames.
MAXFRAME sets an upper limit on the maximum number of unacknowledged packets the PK-88
permits on the radio link at any one time.
MAXFRAME also sets the maximum number of contiguous packets the PK-88 will send during
any given transmission.
If some, but not all, of the outstanding packets are acknowledged, a smaller number
may be transmitted the next time, or new frames may be included in the retransmission,
so that the total number of unacknowledged packet frames does not exceed 'n.'
The 'best' value of MAXFRAME depends on your local channel conditions. In most cases
of keyboard-to-keyboard direct or local operation (links that don't require going
through digipeaters), you can use the default value MAXFRAME 4.
NOTE:
The FRACK counter begins counting from the first ' flag of
each frame. If MAXFRAME is set to 7 and PACLEN is set to
maximum (0), FRACK should be lengthened to prevent the dis
tant station's ACK from colliding with a possibly-premature
retry.
When the amount of packet traffic, the path in use, the digipeaters involved - or
other variables not under your control - make packet operation difficult (as shown by
lots of retries!), you can improve your throughput by reducing MAXFRAME.
Experimental evidence indicates that MAXFRAME 1 or 2 can sometimes produce best
throughput, especially on HF radio, when operating in conditions of multipath
propagation and numerous collisions.
•
If packet traffic is heavy or the path is poor, reduce MAXFRAME to 3, 2 or 1.
•
If the radio link is good, an optimal relationship exists between the parameters
set by these commands. The maximum number of data characters outstanding should
not exceed the receive buffer space of the TNC receiving the data.
Mnemonic: MAX
5-54
Default: 4
COMMAND SUMMARY
PK88-136
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