SNMPv3 Remote Engine ID Discovery

Traps and Informs

SNMPv3 supports two types of notifications, traps and informs.

Traps are unacknowledged notifications sent by agents to managers. Traps are generated by the agent, and the authoritative SNMP engine for a trap packet is the sending SNMP agent. Because the generator of the message and the authoritative engine are the same, there is no need for the SNMPv3 discovery process.

Informs are acknowledged notifications. An agent sends an inform notification and waits for acknowledgement. If the agent does not receive the acknowledgement within the configured timeout period, it resends the inform notification. The agent continues to resend the inform notification until a reply is received or until the maximum retry value is reached. For information about configuring an inform timeout period or configuring a maximum retry value, see Configure SNMP settings.

Remote Engine ID Discovery

Inform packets must contain the management (remote) SNMP engine ID. The agent generates informs, but the authoritative SNMP engine is the manager. To generate valid inform packets and avoid manual configuration of the manager SNMP engine ID, the agent must discover the SNMP engine ID of the manager.

The agent discovers the management SNMP Engine ID by sending a probe message to the manager. The manager response to the probe message is a report message that contains the SNMP engine ID of the authoritative SNMP engine. The agent stores the SNMP engine ID received from the manager in the engine table, and sends inform packets using the manager SNMP engine ID. If the manager SNMP engine ID changes, the discovery process updates the manager SNMP engine ID value in the engine table.

Note

Remote engine ID discovery cannot use SNMP config files created in releases prior to VOSS 8.1. Config files must be saved in Release VOSS 8.1 or higher, and contain local user with specified security level (noAuthNoPriv or authNoPriv or authPriv), to be compatible with remote engine ID discovery.