SNMP GETBULK

The GETBULK operation is normally used for retrieving large amount of data, particularly from large tables. A GETBULK request is made by giving an OID list along with a Max-Repetitions value and a Nonrepeaters value.

 

The GETBULK operation performs a continuous GETNEXT operation based on the Max-Repetitions value. The Nonrepeaters value determines the number of variables in the variable list for which a simple GETNEXT operation has to be done. For the remaining variables, the continuous GETNEXT operation is done based on the Max-Repetitions value.

 

In other words, the SNMP GETBULK operation does a simple GETNEXT operation for the first N variable bindings in the request and does M GETNEXT operation (continuous) for each of the remaining R variable bindings in the request list where

 

N is the minimum of

• the value of the Non-Repeaters field in the request

• the number of variable bindings in the request

M is the Max-Repetitions field of the request

 

R is the maximum of

• the number of variable bindings in the request

• zero

Thus the total number of varbinds in the response message is (N + M x R).

 

explains the usage of high-level API in performing the SNMP GETBULK operation.

 

explains the usage of low-level API in performing the SNMP GETBULK operation.

 

Using High-Level API

 

The additional parameters for the SNMP GETBULK operation can be set using the following methods.

• setMaxRepetitions(int) - the default value is 50.

• setNonRepeaters(int) - the default value is 0.

The snmpGetBulkList() method of the SnmpTarget Bean can be used for the SNMP GETBULK operation.

 

//instantiate the SnmpTarget

SnmpTarget target = new Snmptarget();

//set the host in which the SNMP agent is running

target.setTargetHost("localhost");

//set the OID

target.setObjectID(".1.3.6.1.2.1.3.1");

//perform GETNEXT

String result = target.snmpGetBulkList();

System.out.println("Response: "+result);

 

View the complete example present in <>.

 

Using Low-Level API

 

Refer the topic , which discusses the SNMP GET operation. The additional parameters for the SNMP GETBULK operations can be set using the following methods.

• setMaxRepetitions(int max_rep)

• setNonRepeaters(int non_rep)

To perform an SNMP GETBULK operation, the command constant GETBULK_REQ_MSG defined in the SnmpAPI class is used.

 

//Build GET Request PDU

SnmpPDU pdu = new SnmpPDU();

UDPProtocolOptions option = new UDPProtocolOptions("localhost");

session.setProtocolOptions(option); //sets the host in which the agent is running

pdu.setCommand(SnmpAPI.GETBULK_REQ_MSG);

pdu.setMaxRepetitions(10);

pdu.setNonRepeaters(0);

//Specify OID

SnmpOID oid = new SnmpOID("1.3.1");

pdu.addNull(oid);

 

The rest of the steps will remain the same as the SNMP GET operation. View the complete example present in <>.