Mixing Line Interface Couplers; Spare Lines; Selective Scanning - IBM 3745 Connection And Integration Manual

For LIC Types 5 and 6
Refer to the LIC5/6 Migration and Integration Guide, SA33-0416 or earlier version
of the Connection and Integration Guide, SA33-0129.

Mixing Line Interface Couplers

To calculate the capacity of a low-speed scanner (LSS) connecting LICs with one
or four ports, the following rules apply:
Mixing One-Port and Four-Port LICs
If one-port LICs are mixed with four-port LICs on the same scanner, you should
consider:
Then, compare the two numbers and use the lower number.

Spare Lines

Spare (unused) lines have a weight of zero.

Selective Scanning

For more details on selective scanning, refer to the Introduction, GA33-0092 (for
Models 210 to 610) or GA33-0138 (for Models 130 to 170). This information also
applies to the Models A.
Unlike LICs in earlier communication controllers, 3745 LICs are only scanned if at
least one of the lines connected to them is activated. LICs with inactive lines do
not contribute to the scanner load.
Note: A LIC leaves the scan ring only after all the active lines on the LIC are
deactivated by a Disable command from the control program. An X.21 DTE Clear
command to a X.21 switched line does not disable the line for selective scanning.
1. One-port LICs : LIC types 3, 4B.
2. Four-port LICs: LIC types 1 and 4A.
The permissible number of one-port LICs with the highest speed.
The permissible number of four-port LICs with the highest speed.
Appendix A. LSS Characteristics and Line Weights
A-3