ProxyForwarder ContextEngineId

The ProxyForwarding function appears to be based on the ContextEngineId. How does the sender (originator) know the contextEngineId of the target? Generally, we send snmp requests just using an IP address, does this mean the source needs to know the contextEngineId of all of its targets? (V3 has discovery but we use V2)

Also, SNMP tools like snmpB and net-snmp don’t seem to support setting the ContextEngineId except for V3 packets. So I’m missing something, how do we test a proxy forwarder? It seems that use of ContextEngineId is generally optional yet required for ProxyForwarding, How can ProxyForwarding be used in an SNMPV2 environment?

thanks in advance!

For SNMPv1 and SNMPv2c you can use the SNMP-COMMUNITY-MIB from RFC 3584 ( to define a target contextEngineId for a community.
This allows to use the SNMPv3 based proxy forwarding for community based SNMP packets.