Expand Configuration and Management Manual (H06.21+, J06.10+)

Tuning
Expand Configuration and Management Manual — 529522-013
19 - 21
Summary of Tuning Strategies
Passthrough data has a 4-to-1 priority over locally originated data. This ratio is tuned
fairly well for small passthrough packets. If all nodes in a route are configured for a
large variable packet size (PATHPACKETBYTES modifier) such as 4095 bytes, the
intermediate nodes can send up to 16 Kbytes of passthrough traffic between packets of
a locally originated message.
Configuring a large variable packet size might have undesirable consequences at
nodes in Expand networks that support network applications and provide connectivity
between other network nodes. Using the default value for PATHPACKETBYTES (1024
bytes) allows a maximum of 4 Kbytes of passthrough data between locally originated
packets; however, each local request can now be up to 1 Kbytes.
Summary of Tuning Strategies
Table 19-3 summarizes the strategies that you can use to achieve your tuning goals.
Table 19-3. Summary of Tuning Strategies
Goal Strategies
To optimize resource use
an
d minimize cost
Use the multipacket frame feature for OLTP applications and
the variable packet size feature for bulk data transfers. Both
features can be used on the same path.
Minimize passthrough traffic to save time and capital costs
while maint
aining fault-tolerance.
Use single-line paths where possible.
To maximize throughput Use the multipacket frame feature for OLTP applications and
the
variable packet size feature for bulk data transfers. Both
features can be used on the same path.
Provide adequate communications bandwidth to meet the path
demand
.
Configure Expand line-handler processes to use data
compression (COMPRESS_ON modifier).
Install single high-speed lines rather than multiple low-speed
lines.
To minimize delay Use direct connections between nodes to avoid passthrough
and
its associated delays.
Do not use X.25 or store-and-forward type switches.
Use two or more times the communications line capacity than
is requ
ired to minimize queuing delays.
Configure Expand line-handler proce
sses in lightly loaded
processors.
Configure Expand-over-NAM line-handler processes in the
same p
rocessor if that processor has sufficient capacity.
Avoid satellite connections in multiple hop topologies. (Use
satellite conne
ctions where the network has delays.)