ACC HDLC-NRM (SDLC) User's Guide

Protocol Specific Configuration
Protocol Configuration Values
Chapter 452
Frame Size
This parameter is used to set a limit on the size of the received I-field of a
frame that will be allowed. This parameter does not restrict the size of
I-frames which may be transmitted.
This limit does not include the Address byte, Control byte or FCS
characters. The parameters correspond to byte lengths as follows:
Window - Transmit Window Size
This is the maximum number of unacknowledged transmitted I-frames
allowed. Allowable values are 1 to 7 inclusive. The default (if this
parameter is set to zero) is one (1). This parameter is applicable to both
the primary and secondary stations.
For the primary broadcast terminal, this parameter can be set to govern
the number of broadcast messages that will be sent on a poll cycle.
Increasing this parameter will allow for higher throughput where there
are multiple messages to send, because acknowledgments are not
required for every message transmitted. This parameter is normally set
in conjunction with the capabilities of the receiving station to receive
multiple messages. On a line with many terminals defined, or with large
messages sizes to transmit, the use of a large window size will require
large numbers of transmit buffers to be used. When configuring a large
window size, the terminal unacknowledged queue limit may need to be
increased in order to take advantage of the window.
Frame size parameter Max I-field size (bytes)
0 1024
1 2048
2 3072
3 4096
4 5120
5 6144
6 7168
7 8192