...
This option was added in NMIS 8.5G. It controls how many SNMP PDUs will be packaged into a single SNMP packet.
Like above this option can also be set system-wide or on a per-host basis.
The
SNMP is a fairly complex protocol, and the fact that it primarily operates over UDP does not exactly help matters. As a consequence there are a number of potential problems that affect NMIS' ability to collect information from SNMP agents efficiently and quickly.
snmp_max_msg_size
The primary tunable NMIS configuration setting for SNMP is snmp_max_msg_size, which controls how large a single SNMP packet may be.
This can be set as a system-wide default (in the System menu, under System Configuration), or as a per-host setting (in the Edit Node menu, under Advanced Options).
The default for snmp_max_msg_size is 1472 bytes, just below the 1500 byte packet limit for normal Ethernets. In LAN-only scenarios it is possible to increase this past 1500 bytes: this causes IP fragments and packet reassembly, but unless your LAN is saturated and starving for bandwidth fragmentation is not a problem. The benefit of a larger SNMP packet would be that the data to be collected fits into fewer packets.
snmp_max_repetitions
This option was added in NMIS 8.5G. It controls how many SNMP PDUs will be packaged into a single SNMP packet. The snmp_max_repetitions setting is named a bit oddly - that comes from the SNMP module that NMIS uses: Net::SNMP calls it "-maxrepetitions".
...