The SNMP agent receives requests from, and makes responses to, the SNMP manager.
In addition, the SNMP agent communicates with all DPI2 subagents and SMUX peers on the system. The SNMP agent manages some MIB variables, and all DPI2 subagents and SMUX peers register their MIB variables with the SNMP agent.
When clsnmp (the SNMP manager) issues a request, it is sent to UDP 161 on the SNMP agent. If the request is an SNMPv1 or SNMPv2c request, the SNMP agent will verify the community name and process the request. If the request is an SNMPv3 request, the SNMP agent will attempt to authenticate the user requesting the data and ensure that the user has the access permissions required to fulfill the request by using the authentication keys, and, if the encrypted version is running, privacy keys. If the SNMP agent cannot authenticate the user, or if the user does not have the correct access permissions to fulfill the request, the SNMP agent will not honor the request. For information on creating users in SNMPv3, see Creating users in SNMPv3.
If the user is authenticated and has the correct access permissions, the SNMP agent will fulfill the request. The SNMP agent will locate the MIB variables being requested. If the SNMP agent itself is managing the requested MIB variables, it will process the request and send a response back to the SNMP manager. If a DPI2 subagent or SMUX peer is managing the requested MIB variables, the SNMP agent will forward the request to the DPI2 subagent or SMUX peer on which the MIB variables are managed, allow it to process the request, and will then respond to the SNMP manager.