SNMP Master Agent and the SNMPv3 Proxy Forwarder

The Java DMK 5.0 SNMP master agent is clearly distinct from the SNMPv3 proxy forwarder application as described in RFC 2573 SNMPv3 Applications, and must not be confused with it. The distinction is as follows:

• An SNMP master agent makes it possible to route parts of an SNMP request to a number of subagents. The subagents are completely hidden from the manager. The manager sees a single SNMP entity, the master agent. In an SNMPv3 framework, the manager knows only one SNMP engine ID, namely that of the master agent. A single SNMP request might trigger the retrieval of information from several subagents. How the information is dispatched and retrieved from the subagents is completely controlled by the master agent and is hidden from the manager.

• On the contrary, in a proxy forwarder application, the manager needs to be aware of all the proxied agents. It needs to build a request targeted to a single specific subagent, and it needs to include in the request some information that enables the proxy forwarder application to determine which subagent is the target of the request. In SNMPv3, this is the subagent's SNMP engine ID. In SNMPv1 and SNMPv2, it is a specific community string, for example public@bridge2, where bridge2 identifies the subagent to which the request is forwarded.

The SNMP master agent functionality is thus particularly dedicated to the integration of legacy SNMP agents, in cases where the manager must see only a single entity. An example of such an SNMP master agent is snmpdx on the Solaris operating environment. The proxy forwarder application is more generally used as a firewall, to route information from a public node to agents running in a private network, or to add an additional security layer (for example, SNMPv3 security) to unsecured agents.

Both applications, master agent and proxy forwarder, share a common set of functions, for example, transferring information from one version of the SNMP protocol to another. However, their scope of application is different, and the problems they address are distinct. Java DMK 5.0 supports only the master agent, and does not support the proxy forwarder.