Expand Configuration and Management Manual (G06.24+)

Tuning

Expand Configuration and Management Manual—523347-008

20-3

Multipacket Frame Size

The multipacket frame feature is designed to reduce processor use at nodes where the

workload is high and the configured frame size must remain unchanged. This feature

enables multiple packets to be placed in a single frame (instead of a single packet in a

single frame). The multipacket frame feature is supported for all line types.

The multipacket frame feature does not change the requirement that all Expand line-

handler processes in the network must be configured with the same frame size

(FRAMESIZE modifier). Instead, the multipacket frame feature enables you to increase

the size of frames exchanged on selected paths while still maintaining a single frame

size throughout the network.

Throughput and Frame Size

The improved throughput achieved by the use of the multipacket frame feature

declines when the frame size (FRAMESIZE modifier) is configured to a value that is

greater than the default of 132 words. The multipacket frame feature cannot be used if

the frame size is greater than 516 words. When the frame size is greater than 516

words, the use of multipacket frames actually lowers throughput below that achieved

when the multipacket frame feature is not selected.

Figure 20-1 shows throughput gains and losses resulting from the use of multipacket

frames.

Note. The following information is not relevant for Expand-over-IP lines. HP recommends that

you configure the variable packet size feature (PATHPACKETBYTES modifier) and extended

packet format (L4EXTENDED_ON modifier) for Expand-over-IP lines. These modifiers

effectively override the packet size calculated from the FRAMESIZE modifier.