Expand Configuration and Management Manual (G06.24+)

Planning for ServerNet Clusters
Expand Configuration and Management Manual—523347-008
4-2
Configuration Considerations for Expand and
ServerNet Clusters
•
Every Expand system number and name must be unique across all networks that
can use Expand to communicate.
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Each system in an Expand network can support up to 255 Expand line-handler
processes.
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A node can only belong to one ServerNet cluster.
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The Expand manager process, $ZEXP, must be configured and started.
•
The NonStop ServerNet cluster monitor process, $ZZSCL, must be configured and
started in all S-series nodes connected to a ServerNet cluster.
•
As of G06.20, the Expand routing rules have reverted to the use of simple time
factors. Super time factors, which were based on SPEEDK attributes, are no
longer used. SPEEDK values are now translated into line time factors that have
values from 0 to 186. See also, Considerations for ServerNet Clusters Coexisting
With ServerNet/FX on page 4-3.
•
You must evaluate the distance restrictions between cluster switches and
ServerNet cluster nodes during the planning process. Distance restrictions for
cabling ServerNet clusters are not shown in the topology examples in this section;
refer to the ServerNet Cluster Manual (for the 6770 switch) and the ServerNet
Cluster 6780 Planning and Installation Guide for information about cable-distance
restrictions in ServerNet clusters.
Expand-over-ServerNet line-handler process modifier considerations include:
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FRAMESIZE n modifier: This modifier must be the same for every Expand
line-handler process on every node in the Expand network.
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PATHTF n, LINETF n, SPEEDK n, SPEED n, and RSIZE n, modifiers: These
modifiers set the time factor (TF) for an Expand line. $NCP uses TFs to make
routing decisions. If PATHTF, LINETF, or RSIZE are specified, the value is the time
factor; if SPEEDK or SPEED are specified, the time factor is calculated.
LINETF is the recommended setting for ServerNet lines. PATHTF is equivalent to
LINETF for ServerNet lines. They each have a range of 0 to 186 to designate a
time factor in selecting the best lines and paths to other nodes; the smaller the
number, the more desirable the path.
When you use LINETF, you are setting the time factors directly. For example, if you
prefer to use ServerNet as the best line, ATM as the second best line, and FOX as
the third best line, you would set the LINETF as 1 for ServerNet, 2 for ATM, 3 for
FOX, and a value greater than 3 for all the other paths.
See Routing and Time Factors on page 18-22 for more information about time
factors, including how they are specified and calculated.