Re: get-next question
On 19 Oct 2012, at 19:53, Joan Landry wrote: > Dave, > If you start a walk on a column in table, the walk ends when it reaches the > end of that table. The *walk* does, but the underlying GetNext request doesn't. Try turning on packet dumps for a walk. You should see one final request/response after the last line of output. The GetNext request returns the next valid instance (as per defined behaviour). The walk command looks at the OID, thinks "I don't care about that!", throws it away and stops. That's true for recognising the end of a populated table, and equally for an empty table. Dave Sent from my iPhone -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_sfd2d_oct ___ Net-snmp-users mailing list Net-snmp-users@lists.sourceforge.net Please see the following page to unsubscribe or change other options: https://lists.sourceforge.net/lists/listinfo/net-snmp-users
RE: get-next question
Ok - I see what you are saying - a getnext has to find the next instance for any given oid. So I guess having empty tables back to back is what is timely. -Original Message- From: dave.shi...@gmail.com [mailto:dave.shi...@gmail.com] On Behalf Of Dave Shield Sent: Friday, October 19, 2012 2:22 PM To: Joan Landry Cc: net-snmp-users@lists.sourceforge.net Subject: Re: get-next question On 19 October 2012 18:50, Joan Landry wrote: > When I walk a column in one table, and that table is empty I see that > net-snmp is calling handlers for tables that are next in the oid table > sequence. That is correct. > Is there a reason why net-snmp goes to the next table - when a next > was requested for a given column in one table. No - a GetNext request was issued for a given OID (which just happens to fall within a particular table). The defined behaviour of the GetNext request is that it will return the next valid instance that the agent supports. Not the next instance within a particular range or within the same table - the next valid instance. The agent is working as expected. The SNMP protocol has no idea about the logical structure of MIB information - that's why it can work even without MIB files being available. (That's also why "snmpwalk" will always issue one "extra" GetNext request, and discard the result) > This can take a long time to respond if the subsequent tables are also > empty. If a table is empty, then processing requests for it ought to be quick, surely? If that's taking a long time, then this is probably the thing to address. Dave This email and attachments may contain privileged or confidential information intended only for the addressee(s) indicated. The sender does not waive any of its rights, privileges or protections respecting this information. If you are not the named addressee, an employee, or agent responsible for sending this message to the named addressee (or this message was received by mistake), you are not authorized to read, print, retain, copy or disseminate this message or any part of it. If received in error, please notify us immediately by e-mail, discard any paper copies and delete all electronic files of the email. Computer viruses can be transmitted via email. The recipient should check this email and any attachments for viruses. Email transmission cannot be guaranteed to be secured or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. The sender accepts no liability for any damage caused by any transmitted viruses or errors or omissions in the contents of this message. Overture Networks, Inc. 637 Davis Drive, Morrisville, NC USA 27560 www.overturenetworks.com -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_sfd2d_oct ___ Net-snmp-users mailing list Net-snmp-users@lists.sourceforge.net Please see the following page to unsubscribe or change other options: https://lists.sourceforge.net/lists/listinfo/net-snmp-users
RE: get-next question
Dave, If you start a walk on a column in table, the walk ends when it reaches the end of that table. So realistically calling the handlers for other tables should not occur in this scenario. Do you concur? What I am seeing is that if I walk a column in a table, netsnmp calls a lot of subsequent handlers for tables outside the given column request. If you have enough empty tables back to back the process can be timely. It does not time out - but it is slow just because it is processing through so many empty tables. All of the handlers return SNMP_ENDOFMIBVIEW because they are empty, so there is no processing in the handler itself to speak of. If I return SNMP_NOSUCHINSTANCE netsnmp goes into a never ending loop. -Original Message- From: dave.shi...@gmail.com [mailto:dave.shi...@gmail.com] On Behalf Of Dave Shield Sent: Friday, October 19, 2012 2:22 PM To: Joan Landry Cc: net-snmp-users@lists.sourceforge.net Subject: Re: get-next question On 19 October 2012 18:50, Joan Landry wrote: > When I walk a column in one table, and that table is empty I see that > net-snmp is calling handlers for tables that are next in the oid table > sequence. That is correct. > Is there a reason why net-snmp goes to the next table - when a next > was requested for a given column in one table. No - a GetNext request was issued for a given OID (which just happens to fall within a particular table). The defined behaviour of the GetNext request is that it will return the next valid instance that the agent supports. Not the next instance within a particular range or within the same table - the next valid instance. The agent is working as expected. The SNMP protocol has no idea about the logical structure of MIB information - that's why it can work even without MIB files being available. (That's also why "snmpwalk" will always issue one "extra" GetNext request, and discard the result) > This can take a long time to respond if the subsequent tables are also > empty. If a table is empty, then processing requests for it ought to be quick, surely? If that's taking a long time, then this is probably the thing to address. Dave This email and attachments may contain privileged or confidential information intended only for the addressee(s) indicated. The sender does not waive any of its rights, privileges or protections respecting this information. If you are not the named addressee, an employee, or agent responsible for sending this message to the named addressee (or this message was received by mistake), you are not authorized to read, print, retain, copy or disseminate this message or any part of it. If received in error, please notify us immediately by e-mail, discard any paper copies and delete all electronic files of the email. Computer viruses can be transmitted via email. The recipient should check this email and any attachments for viruses. Email transmission cannot be guaranteed to be secured or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. The sender accepts no liability for any damage caused by any transmitted viruses or errors or omissions in the contents of this message. Overture Networks, Inc. 637 Davis Drive, Morrisville, NC USA 27560 www.overturenetworks.com -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_sfd2d_oct ___ Net-snmp-users mailing list Net-snmp-users@lists.sourceforge.net Please see the following page to unsubscribe or change other options: https://lists.sourceforge.net/lists/listinfo/net-snmp-users
Re: get-next question
On 19 October 2012 18:50, Joan Landry wrote: > When I walk a column in one table, and that table is empty I see that > net-snmp is > calling handlers for tables that are next in the oid table sequence. That is correct. > Is there a reason why net-snmp goes to the next table - when a next > was requested for a given column in one table. No - a GetNext request was issued for a given OID (which just happens to fall within a particular table). The defined behaviour of the GetNext request is that it will return the next valid instance that the agent supports. Not the next instance within a particular range or within the same table - the next valid instance. The agent is working as expected. The SNMP protocol has no idea about the logical structure of MIB information - that's why it can work even without MIB files being available. (That's also why "snmpwalk" will always issue one "extra" GetNext request, and discard the result) > This can take a long time to respond if the subsequent > tables are also empty. If a table is empty, then processing requests for it ought to be quick, surely? If that's taking a long time, then this is probably the thing to address. Dave -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_sfd2d_oct ___ Net-snmp-users mailing list Net-snmp-users@lists.sourceforge.net Please see the following page to unsubscribe or change other options: https://lists.sourceforge.net/lists/listinfo/net-snmp-users
get-next question
When I walk a column in one table, and that table is empty I see that net-snmp is calling handlers for tables that are next in the oid table sequence. This can take a long time to respond if the subsequent tables are also empty. Is there a reason why net-snmp goes to the next table - when a next was requested for a given column in one table. And is there a mechanism to prevent this? Thanks This email and attachments may contain privileged or confidential information intended only for the addressee(s) indicated. The sender does not waive any of its rights, privileges or protections respecting this information. If you are not the named addressee, an employee, or agent responsible for sending this message to the named addressee (or this message was received by mistake), you are not authorized to read, print, retain, copy or disseminate this message or any part of it. If received in error, please notify us immediately by e-mail, discard any paper copies and delete all electronic files of the email. Computer viruses can be transmitted via email. The recipient should check this email and any attachments for viruses. Email transmission cannot be guaranteed to be secured or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. The sender accepts no liability for any damage caused by any transmitted viruses or errors or omissions in the contents of this message. Overture Networks, Inc. 637 Davis Drive, Morrisville, NC USA 27560 www.overturenetworks.com -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_sfd2d_oct ___ Net-snmp-users mailing list Net-snmp-users@lists.sourceforge.net Please see the following page to unsubscribe or change other options: https://lists.sourceforge.net/lists/listinfo/net-snmp-users