Expand Configuration and Management Manual (G06.24+)

Subsystem Description
Expand Configuration and Management Manual—523347-008
18-68
Variable Packet Size Feature
Variable Packet Size Feature
The variable packet size feature is a performance enhancement designed to improve
bulk transfers over all connection types. The variable packet size feature effectively
overrides the packet size calculated from the FRAMESIZE modifier value by allowing
you to configure a maximum packet size, which is used for both single-packet and
multipacket frames, on a per-path basis.
This subsection briefly describes how the variable packet size feature works so that
you can effectively configure and use this feature in your network. It includes the
following topics:
•
Variable Packet Size Configuration on page 18-68
•
Variable Packet Size Considerations on page 18-68
•
Mixing Extended and Nonextended Packets on page 18-69
•
Considerations for Paths Using the Variable Packet Size Feature and the
Multipacket Frame Feature on page 18-70
Variable Packet Size Configuration
You select the variable packet size feature and configure the maximum packet size for
each path in the network by specifying the PATHPACKETBYTES modifier. A value of 0
disables the variable packet size feature. The default is 1024 (bytes), which is also the
minimum size. HP recommends that you select a network-side value for
PATHPACKETBYTES and configure all servers to this value.
The PATHPACKETBYTES modifier is explained in detail in Section 17, Expand
Modifiers.
Variable Packet Size Considerations
Consider the following when configuring the variable packet size feature:
•
The variable packet size feature does not change the requirement that all Expand
line-handler processes in the network must be configured with the same value for
the FRAMESIZE modifier. The FRAMESIZE modifier value is used to provide
compatibility with D-series nodes running pre-D30 software and nonextended
packets that cannot be fragmented. Large packets that are destined for pre-D30
systems are fragmented at the last D30 node in the packet’s route. This ensures
compatibility with nodes that require packets to fit within the size determined by the
FRAMESIZE modifier.
•
The variable packet size feature cannot be used if the FRAMESIZE modifier value
is 517 or more words.