3.1.2. SNMPv1 -> SNMPv2

When converting responses received from a SNMPv1 entity acting in an agent role into responses sent to a SNMPv2 entity acting in a manager role:

1. If a GetResponse-PDU is received, then it is passed unaltered by the proxy agent. Note that even though a SNMPv2 entity will never generate a Response-PDU with a error-status field having a value of `noSuchName', `badValue', or `readOnly', the proxy agent must not change this field. This allows the SNMPv2 entity acting in a manager role to interpret the response correctly.

   If a GetResponse-PDU is received with an error-status field having a value of `tooBig', the proxy agent will remove the contents of the variable-bindings field before propagating the response. Note that even though a SNMPv2 entity will never generate a `tooBig' in response to a GetBulkRequestPDU, the proxy agent must propagate such a response.

2. If a Trap-PDU is received, then it is mapped into a SNMPv2-Trap-PDU. This is done by prepending onto the variable-bindings field two new bindings: sysUpTime.0 [12], which takes its value from the timestamp field of the Trap-PDU; and, snmpTrapOID.0 [13], which is calculated thusly: if the value of generic-trap field is `enterpriseSpecific', then the value used is the concatenation of the enterprise field from the Trap-PDU with two additional sub-identifiers, `0', and the value of the specific-trap field; otherwise, the value of the corresponding trap defined in [13] is used. (For example, if the value of the generic-trap field is `coldStart', then the coldStart trap [13] is used.) Then, one new binding is appended onto the variable-bindings field: snmpTrapEnterpriseOID.0 [13], which takes its value from the enterprise field of the Trap-PDU. To determine the destinations for the SNMPv2-Trap-PDU, the proxy agent applies the procedures defined in Section 4.2.6 of [10], with the exception that no check is made to see if the instances associated with this trap are present in the proxy agent's view.