[SNMP4J] V2 Trap Packet Fragmentation

[Frank Fock]

Hi,

Another user pointed me to the fact that you
probalby using SNMP4J 1.x. In that case
line 499 uses the variable binding list Vector
of the PDU. If you get a NPE there, then
you have set the list to null. You will have
to fix that.

Best regards,
Frank

Am 17.04.2012 23:20, schrieb Frank Fock:
> Hi,
>
> A NullPointerException at that location can be caused
> only by a NULL request ID. How you managed to
> be NULL - I don't know.
> Normally, SNMP4J takes care to set it. So you must have
> done something special.
>
> A SNMP packet fragementation does not exists on UDP
> level in the way you described it (two packets with their
> own header).
>
> Best regards,
> Frank
>
> Am 17.04.2012 00:12, schrieb Amol Rao:
>> ...any thoughts? anyone?
>>
>> On Mon, Apr 16, 2012 at 4:09 PM, Amol Rao<xamolrao at gmail.com>   wrote:
>>> I see the following exception when trap is being sent out. Any pointers?
>>>
>>>
>>> java.lang.NullPointerException
>>>          at org.snmp4j.PDU.getBERPayloadLengthPDU(PDU.java:499)
>>>          at org.snmp4j.PDU.getBERLength(PDU.java:436)
>>>          at org.snmp4j.mp.MPv2c.prepareOutgoingMessage(MPv2c.java:118)
>>>          at org.snmp4j.MessageDispatcherImpl.sendPdu(MessageDispatcherImpl.java:444)
>>>          at org.snmp4j.Snmp.sendMessage(Snmp.java:1078)
>>>          at org.snmp4j.Snmp.send(Snmp.java:878)
>>>          at org.snmp4j.Snmp.send(Snmp.java:871)
>>>          at org.snmp4j.Snmp.send(Snmp.java:836)
>>>          at org.snmp4j.Snmp.notify(Snmp.java:780)
>>>
>>>
>>> Cheers,
>>> Amol
>>>
>>> On Mon, Apr 16, 2012 at 1:05 PM, Amol Rao<xamolrao at gmail.com>   wrote:
>>>> Hi All:
>>>>    Just wanted to reach out and see if anyone encountered this situation.
>>>>
>>>> I am sending out an SNMP trap (~1K size) from an agent system. When
>>>> manager receives the trap, its observe that its divided into multiple
>>>> traps and each trap carries one variable binding - which leads to
>>>> conclusion that the packets are getting fragmented at the SNMP level,
>>>> I wonder why this happens.
>>>>
>>>> I did wireshark and realized that there is no UDP level fragmentation.
>>>>
>>>> Both source (trap generation) and Destination (trap receiver) uses
>>>> snmp4j-1.11.jar but since on the receiving side, I have logic that
>>>> expects the trap to come in as one UDP packets, the whole thing breaks
>>>> apart. Moreover, I observed that its happening on only one system, the
>>>> same code works on another identical system.
>>>>
>>>> Any pointers as to why this could be happening and what is the way around?
>>>>
>>>> I am pretty sure that we are not crossing UDP packet limit, not that
>>>> it would matter at SNMP layer.
>>>>
>>>> Thanks.
>>>>
>>>> Cheers,
>>>> Amol
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