What you should know about osasnmpd

Red Hat Enterprise Linux 8.6 LPAR mode z/VM guest

The osasnmpd subagent requires a master agent to be installed on a Linux® system.

You get the master agent from the net-snmp package. The subagent uses the Agent eXtensibility (AgentX) protocol to communicate with the master agent.

net-snmp is an open source project that is owned by the Open Source Development Network, Inc. (OSDN). For more information about net-snmp visit: 
net-snmp.sourceforge.net

When the master agent (snmpd) is started on a Linux system, it binds to a port (default 161) and awaits requests from SNMP management software. Subagents can connect to the master agent to support MIBs of special interest (for example, OSA-Express MIB). When the osasnmpd subagent is started, it retrieves the MIB objects of the OSA-Express features currently present on the Linux system. It then registers with the master agent the object IDs (OIDs) for which it can provide information.

An OID is a unique sequence of dot-separated numbers (for example, .1.3.6.1.4.1.2) that represents a particular information. OIDs form a hierarchical structure. The longer the OID, that is the more numbers it is made up of, the more specific is the information that is represented by the OID. For example, .1.3.6.1.4.1.2 represents all IBM®-related network information while ..1.3.6.1.4.1.2.6.188 represents all OSA-Express-related information.

A MIB corresponds to a number of OIDs. MIBs provide information about their OIDs including textual representations the OIDs. For example, the textual representation of .1.3.6.1.4.1.2 is .iso.org.dod.internet.private.enterprises.ibm.

The structure of the MIBs might change when updating the OSA-Express Licensed Internal Code (LIC) to a newer level. If MIB changes are introduced by a new LIC level, you must download the appropriate MIB file for the LIC level (see Downloading the IBM OSA-Express MIB). You do not need to update the subagent. Place the updated MIB file in a directory that is searched by the master agent.

Figure 1. OSA-Express SNMP agent flow
This graphic shows the interaction between SNMP master agent and osasnmpd subagent.

Figure 1 illustrates the interaction between the snmpd master agent and the osasnmpd subagent.

Example: This example shows the processes that run after the snmpd master agent and the osasnmpd subagent are started. When you start osasnmpd, a daemon called osasnmpd starts. In the example, PID 687 is the SNMP master agent and PID 729 is the OSA-Express SNMP subagent process: 
ps -ef | grep snmp

USER       PID
root       687     1  0 11:57 pts/1    00:00:00 snmpd
root       729   659  0 13:22 pts/1    00:00:00 osasnmpd

When the master agent receives an SNMP request for an OID that is registered by a subagent, the master agent uses the subagent to collect any requested information and to perform any requested operations. The subagent returns any requested information to the master agent. Finally, the master agent returns the information to the originator of the request.