SNMP API to support Multiple SNMP request for Multiple IP[Host]

SNMP API

kannan.dv

SNMP API to support Multiple SNMP request for Multiple IP[Host]

in SNMP API • 12 years ago

Hi all,

I am using adventnet SNMP API.

Multiple Host + Multiple SNMP request with Different request ID

- Using Single 'SnmpRequestServer' instance.

- creating single 'RequestEvent' and 'ResultListener' for each 'Host'.

- re-config the 'SnmpRequestServer' for an each 'Host' with 'RequestEvent' [multiple re-configuration of 'SnmpRequestServer' with the same config. details for all Host]

so by doing the above i get multiple SNMP request[with Different Request ID] for all Host configured with multiple RequestEvent and multiple 'ResultListener'.

Multiple Host + Multiple SNMP request with Same request ID

- Using Single 'SnmpRequestServer' instance.

- creating single 'RequestEvent' for all Host and multiple 'ResultListener' for each 'Host'.

- one-time config of 'SnmpRequestServer' instance

so by doing the above i get multiple SNMP request[with same Request ID] for all Host configured with Single RequestEvent and multiple 'ResultListener'.

which one of the above is best and optimized one?
is there any better way to send multiple SNMP request for a single SnmpRequestServer?.

Multiple Host ------------------->

SnmpRequestServer [V3 Config] ---------> multiple SNMP Request

Single RequestEvent--------->

is there any SNMP API in adventnet that will send multiple SNMP request with 'one-time' config. of 'SnmpRequestServer' object ?

Regards,

Kannan D V

Replies(1)

amarnatht

SNMP API to support Multiple SNMP request for Multiple IP[Host]

12 years ago

Hi,

If you need to send SNMP requests to multiple devices by using multiple concurrent threads, then you have to use one SnmpRequestServer object per thread that sends requests.

http://www.webnms.com/snmp/help/snmpapi/snmpv3/faqs/beancomponents.html#25
http://www.webnms.com/snmp/help/snmpapi/snmpv3/faqs/lowlevelapi.html#4

Only one ResultListener can be registered with a RequestEvent (by using the method setDestination).

If you use a single RequestEvent among concurrent threads to send requests to multiple devices, then
1. the ResultListener that is set by using RequestEvent.setDestination() in one thread would be reset in another thread.
2. if you register a ResultListener by using SnmpRequestServer.addResultListener() and not by using setDestination(), then it results in all the ResultListeners (even the unintended) of the SnmpRequestServer getting notified with ResultEvent, if any.
3. the requestID, that is set by using RequestEvent.setRequestID(), will be used in multiple threads, which can result in improper correlation of requests and responses.

So, it is better to use a separate RequestEvent in each thread that sends requests.

Thanks,
Amarnath

Guest

SnmpTarget.snmpGet() returns "NULL" instead of null..

12 years ago

Dear Michuneo,

Greetings.

As per the JavaDocs, 'null' will be returned only in case of errors, but not in case of exceptions.

In SNMP V1, if a PDU is constructed with OIDs that are not in the agent, the agent will respond with ErrorStatus set to "noSuchName" . (i.e 2)

But in SNMP V2, as per SNMP standards, this scenario will be treated as "noSuchObjectException" by the agent.

Hence returning 'NULL' instead of 'null' is the expected behavior in this case.
Please be noted that the exception code 128 refers to NoSuchObjectException.

Thanks and Regards,
Pradheep.

pradheep.v Employee

SnmpTarget.snmpGet() returns "NULL" instead of null..

12 years ago

Dear Michuneo,

The return value 'NULL' is expected in your case.
As per the JavaDocs, 'null' will be returned only in case of SNMP errors, but not in case of SNMP exceptions.

If an agent receives

1. an SNMPv1 Get/GetNext Request-PDU with an OID that is not implemented in it, it will respond with errorStatus set to "noSuchName (2)".

2. an SNMPv2 Get/GetNext Request-PDU with an OID that is not implemented in it, it will respond with the respective variable binding's value field set to either 'noSuchObject (128)' or 'noSuchInstance (129)' which are called SNMP exceptions.

Please refer to the following topics in RFC 1905 to get a better understanding on SNMPv2 exceptions .

4.2 PDU Processing

4.2.1 The Get-Request PDU

4.2.2 The GetNext-Request PDU

Also refer to the following topics in RFC 2089, to know the mapping between SNMPv2 exceptions and SNMPv1 errors.

1) 2.2 Mapping SNMPv2 exceptions into SNMPv1

2) 2.3 Mapping noSuchObject and noSuchInstance

3) 2.4 Mapping endOfMibView

NOTE: Please check the error codes and exception codes to see if any error or exception is set (by the agent) on the response message, and then check the result accordingly.

Thanks and Regards,
Pradheep

michuneo

SnmpTarget.snmpGet() returns "NULL" instead of null..

12 years ago

Ooops, I wasnt aware of those snmp v2/v3 exceptions! thanks for the detailed response!

I guess, adding this information to the SnmpTarget.snmpGet() javadoc would be helpfull:

Queries the target and returns as a string the SNMP variable identified by the first Object Identifier stored in this SnmpTarget instance. The following ErrorCodes can be set: errorCodes SNMP_NOT_INIT, INVALID_VERSION, OID_NOT_SPECIFIED, REQ_TIMEDOUT, EMPTY_VAR_BIND, IP_ADDR_NOT_SPECIFIED, SESSION_REMOTE_HOST_UNKNOWN, SECURITYEXP_CONNECTING_REMOTE_HOST, UNKNOWN_ERR, SNMP error's defined in ErrorMessages. v3 only

INVALID_CONTEXT_NAME ,INVALID_CONTEXT_ID.

-> also write about the errorExceptions.

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SNMP API to support Multiple SNMP request for Multiple IP[Host]

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SNMP API to support Multiple SNMP request for Multiple IP[Host]

SnmpTarget.snmpGet() returns "NULL" instead of null..

SnmpTarget.snmpGet() returns "NULL" instead of null..

SnmpTarget.snmpGet() returns "NULL" instead of null..

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