在配置SNMPv3 Trap方式时，需要填写一个Engine ID：

如果是inform方式，则不需要。

什么是Engine ID，它只是一个SNMP实体唯一标识，确保消息是一对一传送，通常由企业编号和默认MAC组成。

The Engine ID is only used by SNMPv3 entities to uniquely identify them. An SNMP agent is considered an authoritative SNMP engine. This means that the agent responds to incoming messages (Get, GetNext, GetBulk, Set), and sends trap messages to a manager.

Each SNMP agent maintains local information that is used in SNMPv3 message exchanges. The default SNMP Engine ID is comprised of the enterprise number and the default MAC address. The SNMP Engine ID must be unique for the administrative domain, so that no two devices in a network have the same Engine ID.

Local information is stored in four MIB variables that are read-only (snmpEngineId, snmpEngineBoots, snmpEngineTime, and snmpEngineMaxMessageSize).

每个设备都有自己的Engine ID，Aruba控制器可以通过以下命令show出

#show snmp engine ID

当然，在控制器测需要配置的engine ID是snmp server的engine ID，同样可以在相应snmp server上查找得到这个参数。例如Aruba Airwave：

对于不知道怎么查询engine ID的设备，可以先通过配置Inform方式，再查看SNMP相关配置信息，可以看到系统自动带出engine ID。