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

Expand Configuration and Management Manual — 529522-013
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19 Tuning
This section provides guidelines for improving network performance and describes the
tools available for measuring performance.
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The Role of Network Tuning on page 19-1
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Performance Factors on page 19-2
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Measuring and Mapping an Expand Network on page 19-22
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Tuning Examples on page 19-28
To obtain the greatest benefit from this section, you should be familiar with the material
presented in Section 2, Expand Overview and Section 3, Planning a Network Design.
The Role of Network Tuning
Tuning is the tactical adjustment of a network’s dynamic resources to achieve some
well-defined performance goals. Tuning is influenced by—and can influence the
activities of—network planning, configuration, management, and troubleshooting.
Tuning Goals
These tuning goals are common to the operation of most networks:
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Optimizing resource use or minimizing cost
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Maximizing the throughput of a certain resource
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Minimizing network delay or improving network response time
In this section, resource use refers to processor utilization (the percentage of time the
processor is busy during a given time period); throughput refers to the amount of
traffic that can be handled by an Expand line-handler process; network delay refers to
the time required to process a network request; and
network response time refers to
user response time (the time between keyboard lock and keyboard unlock).
Although it is not possible to address all three tuning goals simultaneously, you can
take certain actions to improve network efficiency in one or more of these areas. After
goals have been set, tuning should become a routine operations exercise involving the
balancing of network resources.
Ideally, a network should be designed so that it can be adjusted to accommodate
growth of existing applications, permit additional applications, and take advantage of
new technology. Tuning should not adversely affect fault-tolerant network-design goals.
Note. Adjusting the Expand frame size (FRAMESIZE modifier) in an existing network is not
considered in this section because all nodes in the network must be adjusted simultaneously;
this is impractical for most existing networks. With the multipacket frame and variable packet-
size features, the Expand subsystem will send frames larger than the configured frame size.
Therefore, this section discusses network tuning considerations in terms of Expand packet
sizes instead of frame size.