20.6.1 SNMP Proxy Translation

The SnmpProxy object implements the following translation:

• SnmpProxy forwards the request in the protocol specified by the subagent; a get request makes the SnmpProxy object send a get to the subagent, a set request makes the SnmpProxy object send a set to the subagent, and so on.

• If the incoming request is a get-bulk request, and the subagent is an SNMPv1 subagent, SnmpProxy forwards the request as a series of get-next requests.

• If the incoming request is an SNMPv2 or SNMPv3 get or get-next request, and the subagent is an SNMPv1 subagent, SnmpProxy subtracts the varbinds for which an error was returned, and resends the request until either a value or an error is obtained for each varbind. The requests are sent to emulate SNMPv2 or SNMPv3 get and get-next behavior.

• If the incoming request is a set, then two types of behavior are possible, depending on how the SnmpProxy object is configured:

  • The set request can be performed during the check phase, in which case nothing is done during the set

  • The set request can be performed during the set phase, in which case nothing is performed during the check; this is the default behavior

  Whichever solution is chosen has different impacts on the atomicity of set requests. See 20.6.3 Atomicity and Error Handling for details.

• If the incoming request contains SNMPv1 or SNMPv2 community strings, they must be translated using the translateParameters() method. The translateParameters() method reuses the information contained in the SnmpMibRequest PDU to construct new SnmpParams.

  You can overload this method to change its behavior.

• When an SNMPv1 or SNMPv2 request is received, the translateParameters() method is called. The received community string is reused in the forwarded request. If an SNMPv3 request is received, the community string is forwarded as public in a get request and as private in a set request.