Hi Frank,

I'm struggling with a performance issue when querying large numbers of devices 
from a single process. 


If, for example, I simultaneously issue 20 separate 'get' requests to each of 
100 different addresses and repeatedly do that on a half minute cycle, I see 
the CPU usage of my process plateau at a high level.  If I  increase the number 
of devices, I don't see much more of an increase in CPU but the time taken to 
fulfill each request increases on a roughly linear scale in relation to the 
number of devices/requests. 


I have tried using more than one Snmp instance with (as I expected) no obvious 
benefit and I have tried asynchronous requests (where I can reduce CPU load by 
introducing a wait for a response but this comes at the expense of overall 
response times for a given set of 'gets'). 


Is it that ultimately all the responses to my many 'get' requests must arrive 
at a single port (161) on my network interface and that the Snmp reading thread 
can only process them so fast? Is there something I can do to increase 
throughput short of bulking up my queries?

Any help appreciated.

Thanks

Jp





________________________________
 From: "[email protected]" <[email protected]>
To: [email protected] 
Sent: Monday, 3 June 2013, 20:43
Subject: SNMP4J Digest, Vol 111, Issue 3
 

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Today's Topics:

   1. Re: Performance hotspot in Cipher.getInstance() method call
      (Praveen Jain)
   2. Re: V3 Not In Time Window and Client Clock Drift (Elise Atkins)
   3. Re: V3 Not In Time Window and Client Clock Drift (Frank Fock)
   4. Re: V3 Not In Time Window and Client Clock Drift (Elise Atkins)


----------------------------------------------------------------------

Message: 1
Date: Mon, 3 Jun 2013 18:24:19 +0530
From: "Praveen Jain" <[email protected]>
To: "'Frank Fock'" <[email protected]>, <[email protected]>
Subject: Re: [SNMP4J] Performance hotspot in Cipher.getInstance()
    method call
Message-ID: <[email protected]>
Content-Type: text/plain;    charset="us-ascii"

Hi Frank,

Thanks a lot for quick reply. I would really appreciate if you backport the
fix into 1.x branch. Please let me know if there is a place where I can
track that (any issue tracking system). In case the backporting idea is
dropped for 1.x branch, please provide a patch so that I can apply the same
on source code. Thanks.

Regards,
Praveen.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Frank Fock
Sent: Monday, June 03, 2013 2:59 AM
To: [email protected]
Subject: Re: [SNMP4J] Performance hotspot in Cipher.getInstance() method
call

Hi Praveen,

SNMP4J is not caching the cipher object. Apparently, the performance
overhead of retrieving a Cipher instance is not that great with newer Java
versions.
Nevertheless, I am currently working on a caching solution, which does not
introduce a new bootleneek for multi-threaded usage for SNMP4J 2.x.

If it will possible, I will also provide a backport to the 1.x branch.

Best regards,
Frank


Am 30.05.2013 13:03, schrieb Praveen Jain:
> We are using SNMP4J version 1.11.4 for a legacy application running in 
> Java
> 1.4 environment. The application behaved slower than expected and 
> profiling showed that there is hotspot in PrivDES.encrypt() method. 
> This method in turn calls javax.crypto.Cipher.getInstance(String) 
> method (apparently on each message transmission) and 
> Cipher.getInstance(String) is the expensive and CPU intensive call. Can
you please suggest if:
>
> 1.       This might be due wrong way of calling SNMP4J api (and also point
> to a reference code for correct usage to prevent this problem)
>
> 2.       Is this an inherent problem with Java 1.4 code?
>
> 3.       Is this a problem with SNMP 1.11.4 code (it is not caching the
> obtained cipher object)?
>
> Thanks in advance for the help.
>
>  
>
> -Praveen
>
> _______________________________________________
> SNMP4J mailing list
> [email protected]
> http://lists.agentpp.org/mailman/listinfo/snmp4j

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---
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Fax:   +49 7024 8688231

_______________________________________________
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------------------------------

Message: 2
Date: Mon, 03 Jun 2013 11:52:14 -0400
From: Elise Atkins <[email protected]>
To: Frank Fock <[email protected]>, [email protected]
Cc: chuckc <[email protected]>
Subject: Re: [SNMP4J] V3 Not In Time Window and Client Clock Drift
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Frank,

After looking at RFC 3414,  I have a different interpretation. In the 
case 1) the RFC states that the local notion of the value of the 
snmpEngineTime is to be updated to the msgAuthoritativeEngineTime. This 
should mean that the response is in time regardless of how slow or fast 
the authoritative engine's time is running as long as it moves in the 
forward direction when the time check is done in 2).

       b) If the extracted value of msgAuthoritativeEngineID is not the
          same as the value snmpEngineID of the processing SNMP engine
          (meaning this is not the authoritative SNMP engine), then:

          1) if at least one of the following conditions is true:

             - the extracted value of the msgAuthoritativeEngineBoots
               field is greater than the local notion of the value of
               snmpEngineBoots; or,

             - the extracted value of the msgAuthoritativeEngineBoots
               field is equal to the local notion of the value of
               snmpEngineBoots, and the extracted value of
               msgAuthoritativeEngineTime field is greater than the
               value of latestReceivedEngineTime,

             then the LCD entry corresponding to the extracted value of
             the msgAuthoritativeEngineID field is updated, by setting:

             - the local notion of the value of snmpEngineBoots to the
               value of the msgAuthoritativeEngineBoots field,*
*
             *- the local notion of the value of snmpEngineTime to the
               value of the msgAuthoritativeEngineTime field, and*

             - the latestReceivedEngineTime to the value of the value of
               the msgAuthoritativeEngineTime field

         2) if any of the following conditions is true, then the
             message is considered to be outside of the Time Window:

             - the local notion of the value of snmpEngineBoots is
               2147483647;

             - the value of the msgAuthoritativeEngineBoots field is
               less than the local notion of the value of
               snmpEngineBoots; or,

             - the value of the msgAuthoritativeEngineBoots field is
               equal to the local notion of the value of
               snmpEngineBoots and the value of the
               msgAuthoritativeEngineTime field is more than 150
               seconds less than the local notion of the value of
               snmpEngineTime.

>From the above, I think if the reboots are the same and the 
msgAuthoritativeEngineTime is greater then the 
latestReceivedTimeEngineTime, the latestReceivedEngineTime should be 
updated. At that point if you fall down into 2) then the since the

>From release 2.1.2 UsmTimeTable starting at line 174
      if ((entry.getEngineBoots() < time.getEngineBoots()) ||
          ((entry.getEngineBoots() == time.getEngineBoots()) &&
           (time.getTimeDiff() + now >
            entry.getLatestReceivedTime() + 150)) ||
          (time.getEngineBoots() == 2147483647)) {
        if (logger.isDebugEnabled()) {
          logger.debug(
              "CheckTime: received message outside time window (non 
authoritative)");
        }
        return SnmpConstants.SNMPv3_USM_NOT_IN_TIME_WINDOW;
      }
      else {
        if ((entry.getEngineBoots() > time.getEngineBoots()) ||
            ((entry.getEngineBoots() == time.getEngineBoots()) &&
             (entry.getLatestReceivedTime() > 
time.getLatestReceivedTime()))) {
          /* time ok, update values */
          time.setEngineBoots(entry.getEngineBoots());
          time.setLatestReceivedTime(entry.getLatestReceivedTime());
          time.setTimeDiff(entry.getLatestReceivedTime() - now);
        }

Frank Fock wrote:
> Hi Elise,
>
> I would like to give you an update on the issue below.
> I have checked the implementation, your findings, and the current RFC 
> 3414
> and found out, that RFC 3414 precised the description of the incoming
> message handling (section 3.2.7 pages 27-28).
>
> SNMP4J follows that description and is therefore conforming.
> No changes will be applied.
>
> Could you please verify this on your side, too?
>
> Best regards,
> Frank
>
> Am 23.05.2013 17:52, schrieb Elise Atkins:
>> We have been successfully using snmp4j using v3 for both requests and 
>> traps but have recently run into a problem with a client whose engine 
>> time clock runs slow.
>>
>> Initial time synchronization  goes ok and the  SNMP v3 requests and 
>> responses flow properly.  Eventually this client's engine time 
>> becomes more 150 seconds behind the time SNMP4j is expecting and the 
>> responses are marked as Not In Time.  I have looked at RFC 2574 
>> Section 3.2 subsection 7b and the code in the UsmTimeTable class, 
>> checkTime method and have questions about the order of testing for 
>> timeliness.
>>
>> Based on the RFC, I would expect the code to test for the conditions 
>> in 1 first and update if needed before testing the conditions in 2 
>> but the code seems to test in the reverse order. Testing 1 and 
>> updating reboots and time first will allow the client's clock to 
>> drift (fast or slow) as long as it is always increasing and remain in 
>> the time window. Am I missing something here?
>>
>> Elise Atkins
>>
>> The RFC says:
>>
>> 3.2.  Processing an Incoming SNMP Message
>>   7)  If the securityLevel indicates an authenticated message, then
>>       the local values of snmpEngineBoots, snmpEngineTime
>>       and latestReceivedEngineTime
>>       corresponding to the value of the msgAuthoritativeEngineID
>>       field are extracted from the Local Configuration Datastore.
>>
>>       b) If the extracted value of msgAuthoritativeEngineID is not the
>>          same as the value snmpEngineID of the processing SNMP engine
>>          (meaning this is not the authoritative SNMP engine), then:
>>
>>          1) if at least one of the following conditions is true:
>>
>>             - the extracted value of the msgAuthoritativeEngineBoots
>>               field is greater than the local notion of the value of
>>               snmpEngineBoots; or,
>>
>>             - the extracted value of the msgAuthoritativeEngineBoots
>>               field is equal to the local notion of the value of
>>               snmpEngineBoots, and the extracted value of
>>               msgAuthoritativeEngineTime field is greater than the
>>               value of latestReceivedEngineTime,
>>
>>             then the LCD entry corresponding to the extracted value
>>             of the msgAuthoritativeEngineID field is updated, by
>>             setting:
>>
>>                - the local notion of the value of snmpEngineBoots to
>>                  the value of the msgAuthoritativeEngineBoots field,
>>                - the local notion of the value of snmpEngineTime to
>>                  the value of the msgAuthoritativeEngineTime field,
>>                  and
>>                - the latestReceivedEngineTime to the value of the
>>                  value of the msgAuthoritativeEngineTime field.
>>
>>          2) if any of the following conditions is true, then the
>>             message is considered to be outside of the Time Window:
>>
>>             - the local notion of the value of snmpEngineBoots is
>>               2147483647;
>>
>>             - the value of the msgAuthoritativeEngineBoots field is
>>               less than the local notion of the value of
>>               snmpEngineBoots; or,
>>
>>             - the value of the msgAuthoritativeEngineBoots field is
>>               equal to the local notion of the value of
>>               snmpEngineBoots and the value of the
>>               msgAuthoritativeEngineTime field is more than 150
>>               seconds less than the local notion of the value of
>>               snmpEngineTime.
>>
>>             If the message is considered to be outside of the Time
>>             Window then an error indication (notInTimeWindow) is
>>             returned to the calling module.
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> SNMP4J mailing list
>> [email protected]
>> http://lists.agentpp.org/mailman/listinfo/snmp4j
>



------------------------------

Message: 3
Date: Mon, 03 Jun 2013 21:17:57 +0200
From: Frank Fock <[email protected]>
To: [email protected]
Cc: chuckc <[email protected]>, Elise Atkins <[email protected]>,
    [email protected]
Subject: Re: [SNMP4J] V3 Not In Time Window and Client Clock Drift
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Elise,

OK, I am convinced. I reservley checked the implementation with RFC3414 and
overseen your initial point about the order of checks.

I will provide a fix for it (ticket ID is SFJ-75).

The SNMP4J 2.2.2 release (with that fix) is then planned for next week.

Best regards,
Frank


Am 03.06.2013 17:52, schrieb Elise Atkins:
> Frank,
>
> After looking at RFC 3414,  I have a different interpretation. In the 
> case 1) the RFC states that the local notion of the value of the 
> snmpEngineTime is to be updated to the msgAuthoritativeEngineTime. 
> This should mean that the response is in time regardless of how slow 
> or fast the authoritative engine's time is running as long as it moves 
> in the forward direction when the time check is done in 2).
>
>       b) If the extracted value of msgAuthoritativeEngineID is not the
>          same as the value snmpEngineID of the processing SNMP engine
>          (meaning this is not the authoritative SNMP engine), then:
>
>          1) if at least one of the following conditions is true:
>
>             - the extracted value of the msgAuthoritativeEngineBoots
>               field is greater than the local notion of the value of
>               snmpEngineBoots; or,
>
>             - the extracted value of the msgAuthoritativeEngineBoots
>               field is equal to the local notion of the value of
>               snmpEngineBoots, and the extracted value of
>               msgAuthoritativeEngineTime field is greater than the
>               value of latestReceivedEngineTime,
>
>             then the LCD entry corresponding to the extracted value of
>             the msgAuthoritativeEngineID field is updated, by setting:
>
>             - the local notion of the value of snmpEngineBoots to the
>               value of the msgAuthoritativeEngineBoots field,*
> *
>             *- the local notion of the value of snmpEngineTime to the
>               value of the msgAuthoritativeEngineTime field, and*
>
>             - the latestReceivedEngineTime to the value of the value of
>               the msgAuthoritativeEngineTime field
>
>         2) if any of the following conditions is true, then the
>             message is considered to be outside of the Time Window:
>
>             - the local notion of the value of snmpEngineBoots is
>               2147483647;
>
>             - the value of the msgAuthoritativeEngineBoots field is
>               less than the local notion of the value of
>               snmpEngineBoots; or,
>
>             - the value of the msgAuthoritativeEngineBoots field is
>               equal to the local notion of the value of
>               snmpEngineBoots and the value of the
>               msgAuthoritativeEngineTime field is more than 150
>               seconds less than the local notion of the value of
>               snmpEngineTime.
>
> From the above, I think if the reboots are the same and the 
> msgAuthoritativeEngineTime is greater then the 
> latestReceivedTimeEngineTime, the latestReceivedEngineTime should be 
> updated. At that point if you fall down into 2) then the since the
>
> From release 2.1.2 UsmTimeTable starting at line 174
>      if ((entry.getEngineBoots() < time.getEngineBoots()) ||
>          ((entry.getEngineBoots() == time.getEngineBoots()) &&
>           (time.getTimeDiff() + now >
>            entry.getLatestReceivedTime() + 150)) ||
>          (time.getEngineBoots() == 2147483647)) {
>        if (logger.isDebugEnabled()) {
>          logger.debug(
>              "CheckTime: received message outside time window (non 
> authoritative)");
>        }
>        return SnmpConstants.SNMPv3_USM_NOT_IN_TIME_WINDOW;
>      }
>      else {
>        if ((entry.getEngineBoots() > time.getEngineBoots()) ||
>            ((entry.getEngineBoots() == time.getEngineBoots()) &&
>             (entry.getLatestReceivedTime() > 
> time.getLatestReceivedTime()))) {
>          /* time ok, update values */
>          time.setEngineBoots(entry.getEngineBoots());
> time.setLatestReceivedTime(entry.getLatestReceivedTime());
>          time.setTimeDiff(entry.getLatestReceivedTime() - now);
>        }
>
> Frank Fock wrote:
>> Hi Elise,
>>
>> I would like to give you an update on the issue below.
>> I have checked the implementation, your findings, and the current RFC 
>> 3414
>> and found out, that RFC 3414 precised the description of the incoming
>> message handling (section 3.2.7 pages 27-28).
>>
>> SNMP4J follows that description and is therefore conforming.
>> No changes will be applied.
>>
>> Could you please verify this on your side, too?
>>
>> Best regards,
>> Frank
>>
>> Am 23.05.2013 17:52, schrieb Elise Atkins:
>>> We have been successfully using snmp4j using v3 for both requests 
>>> and traps but have recently run into a problem with a client whose 
>>> engine time clock runs slow.
>>>
>>> Initial time synchronization  goes ok and the  SNMP v3 requests and 
>>> responses flow properly.  Eventually this client's engine time 
>>> becomes more 150 seconds behind the time SNMP4j is expecting and the 
>>> responses are marked as Not In Time.  I have looked at RFC 2574 
>>> Section 3.2 subsection 7b and the code in the UsmTimeTable class, 
>>> checkTime method and have questions about the order of testing for 
>>> timeliness.
>>>
>>> Based on the RFC, I would expect the code to test for the conditions 
>>> in 1 first and update if needed before testing the conditions in 2 
>>> but the code seems to test in the reverse order. Testing 1 and 
>>> updating reboots and time first will allow the client's clock to 
>>> drift (fast or slow) as long as it is always increasing and remain 
>>> in the time window. Am I missing something here?
>>>
>>> Elise Atkins
>>>
>>> The RFC says:
>>>
>>> 3.2.  Processing an Incoming SNMP Message
>>>   7)  If the securityLevel indicates an authenticated message, then
>>>       the local values of snmpEngineBoots, snmpEngineTime
>>>       and latestReceivedEngineTime
>>>       corresponding to the value of the msgAuthoritativeEngineID
>>>       field are extracted from the Local Configuration Datastore.
>>>
>>>       b) If the extracted value of msgAuthoritativeEngineID is not the
>>>          same as the value snmpEngineID of the processing SNMP engine
>>>          (meaning this is not the authoritative SNMP engine), then:
>>>
>>>          1) if at least one of the following conditions is true:
>>>
>>>             - the extracted value of the msgAuthoritativeEngineBoots
>>>               field is greater than the local notion of the value of
>>>               snmpEngineBoots; or,
>>>
>>>             - the extracted value of the msgAuthoritativeEngineBoots
>>>               field is equal to the local notion of the value of
>>>               snmpEngineBoots, and the extracted value of
>>>               msgAuthoritativeEngineTime field is greater than the
>>>               value of latestReceivedEngineTime,
>>>
>>>             then the LCD entry corresponding to the extracted value
>>>             of the msgAuthoritativeEngineID field is updated, by
>>>             setting:
>>>
>>>                - the local notion of the value of snmpEngineBoots to
>>>                  the value of the msgAuthoritativeEngineBoots field,
>>>                - the local notion of the value of snmpEngineTime to
>>>                  the value of the msgAuthoritativeEngineTime field,
>>>                  and
>>>                - the latestReceivedEngineTime to the value of the
>>>                  value of the msgAuthoritativeEngineTime field.
>>>
>>>          2) if any of the following conditions is true, then the
>>>             message is considered to be outside of the Time Window:
>>>
>>>             - the local notion of the value of snmpEngineBoots is
>>>               2147483647;
>>>
>>>             - the value of the msgAuthoritativeEngineBoots field is
>>>               less than the local notion of the value of
>>>               snmpEngineBoots; or,
>>>
>>>             - the value of the msgAuthoritativeEngineBoots field is
>>>               equal to the local notion of the value of
>>>               snmpEngineBoots and the value of the
>>>               msgAuthoritativeEngineTime field is more than 150
>>>               seconds less than the local notion of the value of
>>>               snmpEngineTime.
>>>
>>>             If the message is considered to be outside of the Time
>>>             Window then an error indication (notInTimeWindow) is
>>>             returned to the calling module.
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> SNMP4J mailing list
>>> [email protected]
>>> http://lists.agentpp.org/mailman/listinfo/snmp4j
>>
>

-- 
---
AGENT++
Maximilian-Kolbe-Str. 10
73257 Koengen, Germany
https://agentpp.com
Phone: +49 7024 8688230
Fax:   +49 7024 8688231



------------------------------

Message: 4
Date: Mon, 03 Jun 2013 15:43:03 -0400
From: Elise Atkins <[email protected]>
To: Frank Fock <[email protected]>
Cc: chuckc <[email protected]>, [email protected]
Subject: Re: [SNMP4J] V3 Not In Time Window and Client Clock Drift
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Thank you. Look forward to the new release.
Elise

Frank Fock wrote:
> Elise,
>
> OK, I am convinced. I reservley checked the implementation with 
> RFC3414 and
> overseen your initial point about the order of checks.
>
> I will provide a fix for it (ticket ID is SFJ-75).
>
> The SNMP4J 2.2.2 release (with that fix) is then planned for next week.
>
> Best regards,
> Frank
>
>
> Am 03.06.2013 17:52, schrieb Elise Atkins:
>> Frank,
>>
>> After looking at RFC 3414,  I have a different interpretation. In the 
>> case 1) the RFC states that the local notion of the value of the 
>> snmpEngineTime is to be updated to the msgAuthoritativeEngineTime. 
>> This should mean that the response is in time regardless of how slow 
>> or fast the authoritative engine's time is running as long as it 
>> moves in the forward direction when the time check is done in 2).
>>
>>       b) If the extracted value of msgAuthoritativeEngineID is not the
>>          same as the value snmpEngineID of the processing SNMP engine
>>          (meaning this is not the authoritative SNMP engine), then:
>>
>>          1) if at least one of the following conditions is true:
>>
>>             - the extracted value of the msgAuthoritativeEngineBoots
>>               field is greater than the local notion of the value of
>>               snmpEngineBoots; or,
>>
>>             - the extracted value of the msgAuthoritativeEngineBoots
>>               field is equal to the local notion of the value of
>>               snmpEngineBoots, and the extracted value of
>>               msgAuthoritativeEngineTime field is greater than the
>>               value of latestReceivedEngineTime,
>>
>>             then the LCD entry corresponding to the extracted value of
>>             the msgAuthoritativeEngineID field is updated, by setting:
>>
>>             - the local notion of the value of snmpEngineBoots to the
>>               value of the msgAuthoritativeEngineBoots field,*
>> *
>>             *- the local notion of the value of snmpEngineTime to the
>>               value of the msgAuthoritativeEngineTime field, and*
>>
>>             - the latestReceivedEngineTime to the value of the value of
>>               the msgAuthoritativeEngineTime field
>>
>>         2) if any of the following conditions is true, then the
>>             message is considered to be outside of the Time Window:
>>
>>             - the local notion of the value of snmpEngineBoots is
>>               2147483647;
>>
>>             - the value of the msgAuthoritativeEngineBoots field is
>>               less than the local notion of the value of
>>               snmpEngineBoots; or,
>>
>>             - the value of the msgAuthoritativeEngineBoots field is
>>               equal to the local notion of the value of
>>               snmpEngineBoots and the value of the
>>               msgAuthoritativeEngineTime field is more than 150
>>               seconds less than the local notion of the value of
>>               snmpEngineTime.
>>
>> From the above, I think if the reboots are the same and the 
>> msgAuthoritativeEngineTime is greater then the 
>> latestReceivedTimeEngineTime, the latestReceivedEngineTime should be 
>> updated. At that point if you fall down into 2) then the since the
>>
>> From release 2.1.2 UsmTimeTable starting at line 174
>>      if ((entry.getEngineBoots() < time.getEngineBoots()) ||
>>          ((entry.getEngineBoots() == time.getEngineBoots()) &&
>>           (time.getTimeDiff() + now >
>>            entry.getLatestReceivedTime() + 150)) ||
>>          (time.getEngineBoots() == 2147483647)) {
>>        if (logger.isDebugEnabled()) {
>>          logger.debug(
>>              "CheckTime: received message outside time window (non 
>> authoritative)");
>>        }
>>        return SnmpConstants.SNMPv3_USM_NOT_IN_TIME_WINDOW;
>>      }
>>      else {
>>        if ((entry.getEngineBoots() > time.getEngineBoots()) ||
>>            ((entry.getEngineBoots() == time.getEngineBoots()) &&
>>             (entry.getLatestReceivedTime() > 
>> time.getLatestReceivedTime()))) {
>>          /* time ok, update values */
>>          time.setEngineBoots(entry.getEngineBoots());
>> time.setLatestReceivedTime(entry.getLatestReceivedTime());
>>          time.setTimeDiff(entry.getLatestReceivedTime() - now);
>>        }
>>
>> Frank Fock wrote:
>>> Hi Elise,
>>>
>>> I would like to give you an update on the issue below.
>>> I have checked the implementation, your findings, and the current 
>>> RFC 3414
>>> and found out, that RFC 3414 precised the description of the incoming
>>> message handling (section 3.2.7 pages 27-28).
>>>
>>> SNMP4J follows that description and is therefore conforming.
>>> No changes will be applied.
>>>
>>> Could you please verify this on your side, too?
>>>
>>> Best regards,
>>> Frank
>>>
>>> Am 23.05.2013 17:52, schrieb Elise Atkins:
>>>> We have been successfully using snmp4j using v3 for both requests 
>>>> and traps but have recently run into a problem with a client whose 
>>>> engine time clock runs slow.
>>>>
>>>> Initial time synchronization  goes ok and the  SNMP v3 requests and 
>>>> responses flow properly.  Eventually this client's engine time 
>>>> becomes more 150 seconds behind the time SNMP4j is expecting and 
>>>> the responses are marked as Not In Time.  I have looked at RFC 2574 
>>>> Section 3.2 subsection 7b and the code in the UsmTimeTable class, 
>>>> checkTime method and have questions about the order of testing for 
>>>> timeliness.
>>>>
>>>> Based on the RFC, I would expect the code to test for the 
>>>> conditions in 1 first and update if needed before testing the 
>>>> conditions in 2 but the code seems to test in the reverse order. 
>>>> Testing 1 and updating reboots and time first will allow the 
>>>> client's clock to drift (fast or slow) as long as it is always 
>>>> increasing and remain in the time window. Am I missing something here?
>>>>
>>>> Elise Atkins
>>>>
>>>> The RFC says:
>>>>
>>>> 3.2.  Processing an Incoming SNMP Message
>>>>   7)  If the securityLevel indicates an authenticated message, then
>>>>       the local values of snmpEngineBoots, snmpEngineTime
>>>>       and latestReceivedEngineTime
>>>>       corresponding to the value of the msgAuthoritativeEngineID
>>>>       field are extracted from the Local Configuration Datastore.
>>>>
>>>>       b) If the extracted value of msgAuthoritativeEngineID is not the
>>>>          same as the value snmpEngineID of the processing SNMP engine
>>>>          (meaning this is not the authoritative SNMP engine), then:
>>>>
>>>>          1) if at least one of the following conditions is true:
>>>>
>>>>             - the extracted value of the msgAuthoritativeEngineBoots
>>>>               field is greater than the local notion of the value of
>>>>               snmpEngineBoots; or,
>>>>
>>>>             - the extracted value of the msgAuthoritativeEngineBoots
>>>>               field is equal to the local notion of the value of
>>>>               snmpEngineBoots, and the extracted value of
>>>>               msgAuthoritativeEngineTime field is greater than the
>>>>               value of latestReceivedEngineTime,
>>>>
>>>>             then the LCD entry corresponding to the extracted value
>>>>             of the msgAuthoritativeEngineID field is updated, by
>>>>             setting:
>>>>
>>>>                - the local notion of the value of snmpEngineBoots to
>>>>                  the value of the msgAuthoritativeEngineBoots field,
>>>>                - the local notion of the value of snmpEngineTime to
>>>>                  the value of the msgAuthoritativeEngineTime field,
>>>>                  and
>>>>                - the latestReceivedEngineTime to the value of the
>>>>                  value of the msgAuthoritativeEngineTime field.
>>>>
>>>>          2) if any of the following conditions is true, then the
>>>>             message is considered to be outside of the Time Window:
>>>>
>>>>             - the local notion of the value of snmpEngineBoots is
>>>>               2147483647;
>>>>
>>>>             - the value of the msgAuthoritativeEngineBoots field is
>>>>               less than the local notion of the value of
>>>>               snmpEngineBoots; or,
>>>>
>>>>             - the value of the msgAuthoritativeEngineBoots field is
>>>>               equal to the local notion of the value of
>>>>               snmpEngineBoots and the value of the
>>>>               msgAuthoritativeEngineTime field is more than 150
>>>>               seconds less than the local notion of the value of
>>>>               snmpEngineTime.
>>>>
>>>>             If the message is considered to be outside of the Time
>>>>             Window then an error indication (notInTimeWindow) is
>>>>             returned to the calling module.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> SNMP4J mailing list
>>>> [email protected]
>>>> http://lists.agentpp.org/mailman/listinfo/snmp4j
>>>
>>
>



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