4.2.1. The GetRequest-PDU

A GetRequest-PDU is generated and transmitted at the request of a SNMPv2 application.

Upon receipt of a GetRequest-PDU, the receiving SNMPv2 entity processes each variable binding in the variable-binding list to produce a Response-PDU. All fields of the Response-PDU have the same values as the corresponding fields of the received request except as indicated below. Each variable binding is processed as follows:

1. If the variable binding's name exactly matches the name of a variable accessible by this request, then the variable binding's value field is set to the value of the named variable.

2. Otherwise, if the variable binding's name does not have an OBJECT IDENTIFIER prefix which exactly matches the OBJECT IDENTIFIER prefix of any (potential) variable accessible by this request, then its value field is set to `noSuchObject'.

3. Otherwise, the variable binding's value field is set to `noSuchInstance'.

If the processing of any variable binding fails for a reason other than listed above, then the Response-PDU is re-formatted with the same values in its request-id and variable-bindings fields as the received GetRequest-PDU, with the value of its error-status field set to `genErr', and the value of its error-index field is set to the index of the failed variable binding.

Otherwise, the value of the Response-PDU's error-status field is set to `noError', and the value of its error-index field is zero.

The generated Response-PDU is then encapsulated into a message. If the size of the resultant message is less than or equal to both a local constraint and the maximum message size of the originator, it is transmitted to the originator of the GetRequest-PDU.

Otherwise, an alternate Response-PDU is generated. This alternate Response-PDU is formatted with the same value in its request-id field as the received GetRequest-PDU, with the value of its error-status field set to `tooBig', the value of its error-index field set to zero, and an empty variable-bindings field. This alternate Response-PDU is then encapsulated into a message. If the size of the resultant message is less than or equal to both a local constraint and the maximum message size of the originator, it is transmitted to the originator of the GetRequest-PDU. Otherwise, the snmpSilentDrops [9] counter is incremented and the resultant message is discarded.