Hello, I have recently run into a problem where "sndMsgMaxSize" would be most helpful, but is unfortunately not.
I have a number of devices that support such lame message sizes as 490 bytes and even lower. My code for issuing an SNMPGET, before meeting these devices, was simply to batch up OIDs in chunks of 20 and send them off. I found 20 to be a good number for keeping the PDU size within acceptable limits of all devices before these. I have since begun implementing routine scans of SNMP-FRAMEWORK-MIB::snmpEngineMaxMessageSize.0, and using that value to determine what the sndMsgMaxSize should be when talking to that device. Indeed, I found that I could set sndMsgMaxSize and snmp_sess_send would even set the error code to SNMPERR_TOO_LONG. Perfect. However, after going over the source code, I see that net-snmp will not break down my PDU and send it for me. Fine, okay. My next idea was this: 1. Add all of the OIDs that I want to get to a PDU called "currentPdu". 2. Create an empty PDU called "extraPdu". 3. Loop until "currentPdu" is empty. 3a. Send PDU "currentPdu". 3b. Okay? 3b1. Swap "currentPdu" and "extraPdu". 3b2. Continue to top of loop. 3c. (We didn't send the PDU.) 3d. If the error was NOT "SNMPERR_TOO_LONG", then just quit. 3e. (We need to trim our PDU.) 3f. Remove the LAST varbind from "currentPdu" and add it as the FIRST varbind on "extraPdu". 3g. Continue to top of loop. Essentially, if we try to send a message that's too big, we get a specific error back. We then keep popping OIDs out of the PDU until it sends successfully. We then repeat the process for the second PDU that stored all of the "too big" OIDs from the original PDU (in their proper, original order). I see that there is an "snmp_pdu_add_variable" function to add new OIDs to a PDU, but I don't see any other varbind manipulation routines for PDUs that would allow me to accomplish my task of trimming the PDU down to a manageable size. Has anyone else encountered this problem? If so, do you have a good solution? ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Net-snmp-coders mailing list Net-snmp-coders@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/net-snmp-coders
