ACC X.25 Protocol User's Guide

ZX25D X.25 Protocol Driver
Configuration
Chapter 344
many transmitted messages, delayed responses from
the network, and/or a large window size. It is
recommended that this bit always be set.
IRX The “Incomplete Rx Message” option is for use on
Muxes with high loads (that is, many logical channels
and/or large messages) and allows the Mux to send
partially complete messages to the application with a
“More” bit set in the tag byte (bit 4), thus reducing the
demand on receive buffers in the Mux. If this bit is not
set, the theoretical maximum sized message that can
be received is approximately 22K bytes in length. This
bit must be set if messages larger than this are
received on a VC. Note that the operational maximum
sized message may be considerable less than 22K bytes
depending on many other configuration factors. In most
cases, this bit should be set.
HLD The “Hold Acknowledgments” option results in Level-3
acknowledgments for received packets being
suppressed until the Rx window is full. Setting this bit
also prevents a Level-3 acknowledgment when the T2
timer expires.
RRP This bit controls the Level-3 acknowledgment (RR)
policy following by the X.25 firmware. If this bit is set
to 0, a Level-3 acknowledgment is generated for every
inbound data packet. If this bit is set to 1, the firmware
attempts to minimize the number of Level-3
acknowledgments that are sent.
WARNING The “Hold Acknowledgments” option may cause the remote
device to time-out if it has the T25 timer running.
The default Option Word for X25.LAPB is defined in
/opt/acc/cfg/zcomdevice.txt to be 2. Refer to the ACC Utilities Reference
Guide, chapter on ZDGEN, for more information on changing this default
value.