Expand Configuration and Management Manual (G06.24+)

Subsystem Description
Expand Configuration and Management Manual—523347-008
18-23
Setting Time Factors
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Expand’s multi-CPU paths are made up of two or more direct paths to the same
neighbor that operate in parallel. So the calculation of a multi-CPU path time factor
is done in a very similar way as the time factor for a multi-line path (where you
have parallel lines).
The time factor for a path to a remote (multi-hop) node is calculated as the sum of the
time factors for all direct (single-hop) paths that make up the path. The result is the
called the aggregate TF for the entire multi-hop path.
Setting Time Factors
The PATHTF, LINETF, SPEEDK, SPEED, and RSIZE modifiers all establish time
factors. You set these modifiers by using the ALTER LINE or the ALTER DEVICE
command, the latter of which alters the line device and is retained through a cold load.
As of G06.20, it is recommended that you use LINETF to specify priorities for individual
lines. PATHTF changes routing behavior for multi-line paths, forcing a constant time
factor rather than letting the path’s time factor be the aggregate of the time factors of
the lines that are currently operational.
For example, you can use PATHTF to set your own time factor in selecting the path, so
if you prefer to use ServerNet as the best path, ATM as the second best path, and FOX
as the third best path, then you would set the PATHTF as 1 for ServerNet, 2 for ATM, 3
for FOX, and a value greater than 3 for all other paths. The smaller the number, the
more desirable the path. The range is 0 through 186.
The order of selection for the various time factor parameters is as follows (highest to
lowest): PATHTF, LINETF, SPEEDK, SPEED, or RSIZE. One of these time-factor
parameters must be set, else the line handler will display a configuration error.
PATHTF n has a range of 0 to 186 to designate the time factor in selecting the best
path to other nodes. A smaller number indicates a more desirable path for routing.
PATHTF overrides all other parameters in calculating the time factor for the path. When
PATHTF is set for a multi-line path, the line state and number of lines in the path are
ignored and the PATHTF setting is a constant value assigned to the time factor for the
path. PATHTF used on a single-line path device is the same as using LINETF on the
line device.
LINETF n has a range of 0 to 186 to designate the line time factor in selecting the best
path to other nodes in the network. A smaller number indicates a more desirable path
for routing. LINETF overrides the RSIZE, SPEED, or SPEEDK parameters in
calculating the time factor for the line.
SPEEDK n, which was the recommended setting before G06.20, can still be used but
now behaves differently and is no longer recommended. If you use this setting, every
line equivalent to or faster than a FOX line has a time factor of 1.
SPEED n provides a way of creating the time factor, and has a maximum value of
244,000. Its use is no longer recommended.