[SNMP4J] seek clarification on SNMP v3 set operation

[dajiang]

Hi list,

Here is my question or puzzle:

Based on SnmpRequest in the SNMP4J package, I am writing some Java code 
to do SNMP (v3) set on some device. Basically it works.
For my curiosity, I use Wireshark to capture packet exchanges between my 
code and the device; and compare them with a case whereby I use 
iReasoning MIB browser to do the SNMP v3 set operation.

To my surprise, although both methods work, they use different packet 
exchanges.
For MIB browser, the followings are the packets exchange:
192.168.1.222 is the setter, while 192.168.1.20 is the device.

No.     Time        Source                Destination           Protocol 
Length Info
       2 5.598626    192.168.1.222         192.168.1.20          
SNMP     113    get-request

No.     Time        Source                Destination           Protocol 
Length Info
       3 5.822897    192.168.1.20          192.168.1.222         
SNMP     156    report 1.3.6.1.6.3.15.1.1.4.0
No.     Time        Source                Destination           Protocol 
Length Info
       4 5.823536    192.168.1.222         192.168.1.20          
SNMP     183    encryptedPDU: privKey Unknown

No.     Time        Source                Destination           Protocol 
Length Info
       5 8.193932    192.168.1.20          192.168.1.222         
SNMP     238    encryptedPDU: privKey Unknown

No.     Time        Source                Destination           Protocol 
Length Info
       6 8.289356    192.168.1.20          192.168.1.222         
SNMP     183    encryptedPDU: privKey Unknown

For SNMP4J library, these are the packets:

No.     Time        Source                Destination           Protocol 
Length Info
       8 82.873071   192.168.1.222         192.168.1.20          
SNMP     103    set-request

No.     Time        Source                Destination           Protocol 
Length Info
       9 83.734217   192.168.1.20          192.168.1.222         
SNMP     146    report 1.3.6.1.6.3.15.1.1.4.0

No.     Time        Source                Destination           Protocol 
Length Info
      10 83.939049   192.168.1.222         192.168.1.20          
SNMP     183    encryptedPDU: privKey Unknown

No.     Time        Source                Destination           Protocol 
Length Info
      11 83.941801   192.168.1.20          192.168.1.222         
SNMP     167    report 1.3.6.1.6.3.15.1.1.2.0

No.     Time        Source                Destination           Protocol 
Length Info
      12 83.942512   192.168.1.222         192.168.1.20          
SNMP     183    encryptedPDU: privKey Unknown

No.     Time        Source                Destination           Protocol 
Length Info
      13 84.881048   192.168.1.222         192.168.1.20          
SNMP     183    encryptedPDU: privKey Unknown

No.     Time        Source                Destination           Protocol 
Length Info
      14 85.512266   192.168.1.20          192.168.1.222         
SNMP     238    encryptedPDU: privKey Unknown

No.     Time        Source                Destination           Protocol 
Length Info
      15 85.523770   192.168.1.20          192.168.1.222         
SNMP     238    encryptedPDU: privKey Unknown

No.     Time        Source                Destination           Protocol 
Length Info
      16 85.637430   192.168.1.20          192.168.1.222         
SNMP     183    encryptedPDU: privKey Unknown

No.     Time        Source                Destination           Protocol 
Length Info
      17 85.638656   192.168.1.20          192.168.1.222         
SNMP     183    encryptedPDU: privKey Unknown

No.     Time        Source                Destination           Protocol 
Length Info
      19 163.383344  192.168.1.20          192.168.1.222         
SNMP     238    encryptedPDU: privKey Unknown

Other than exchanged packets numbers, the biggest difference is MIB 
browser using get-request, while SNMP4J using set-request. Can someone 
help me understand why there are differences? Do I use SNMP4J wrongly? Thx.

Best Regards