Re: [c-nsp] SNMP MIB update interval on CISCO?
Thanks for the information. Do the routers maintain a timestamp of when they last updated their MIB. The time difference between the updates will give me a good indication of the average traffic being observed by the router. Thanks, -Proveen -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of mack Sent: Tuesday, March 25, 2008 5:42 PM To: cisco-nsp@puck.nether.net Subject: Re: [c-nsp] SNMP MIB update interval on CISCO? On the 6500/7600 platform you can set: service counters max age 5 Obviously this is platform specific. On high CPU load SNMP counters may be updated at a longer interval. At extreme levels SNMP may stop updating completely until the load goes down. Most platforms have a best-effort interval of 10 seconds. As for the accuracy: % Accuracy~=update interval*100/sample interval So with a 60 second sample interval and a ten second update interval you can have a variance of ~17%. With a 5 minute sample interval the variance is ~3%. The accuracy is an approximation as the update interval is best-effort. To sum it up you can sample slower and get more accurate readings or faster and get less accurate readings. -- LR Mack McBride Network Administrator Alpha Red, Inc. Message: 9 Date: Tue, 25 Mar 2008 20:02:23 - From: Dean Smith [EMAIL PROTECTED] Subject: Re: [c-nsp] SNMP MIB update interval on CISCO? To: cisco-nsp@puck.nether.net Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=us-ascii Basically - No. Counters like those are really only valid for polling every minute at a minimum and even then you can occasionally see strange affects due to the internal updates happening out of sync. If you essentially need granularity of a second or so sampling you probably need an external tool. Dean -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gurung, Provin Sent: 25 March 2008 17:02 To: cisco-nsp@puck.nether.net Subject: [c-nsp] SNMP MIB update interval on CISCO? I have a question about how to get the cisco routers updates rate of one of the snmp mib entries. Background: I am using a cisco 3640 series router running ios 12.4. I am cyclically doing snmpwalks to get the number of bytes transmitted on an output interface for a particular Diff serv code point. The actually snmpwalk call is for cbQosMatchPrePolicyByte (enterprises.9.9.166.1.16.1.1.5) in the CISCO-CLASS-BASED-QOS-MIB mib. My problem. I would like to compute the number of bytes sent per second as quickly and accurately as possible. However I found that the above mib entry can be updated anywhere from 6 to 10 seconds. Sometimes if I poll this snmp entry every 8 seconds the entry hasn't had a chance to change yet and my message rate incorrectly is 0 kbs. My question: 1) Is there somewhere in the mib or cisco's command line interface where I can get the cyclic rate that is being used? Or the timestamp when the MIB entries are being updated? 2) Is it possible to set this rate via snmp or the cisco command line interface and make the router update at a fixed interval of my choosing? 3) Alternatively, Is there a way to generate SNMP traps when router updates its traffic statistics for some DSCP value? Thanks for any inputs, -Proveen ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
Re: [c-nsp] SNMP MIB update interval on CISCO?
Basically - No. Counters like those are really only valid for polling every minute at a minimum and even then you can occasionally see strange affects due to the internal updates happening out of sync. If you essentially need granularity of a second or so sampling you probably need an external tool. Dean -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gurung, Provin Sent: 25 March 2008 17:02 To: cisco-nsp@puck.nether.net Subject: [c-nsp] SNMP MIB update interval on CISCO? I have a question about how to get the cisco routers updates rate of one of the snmp mib entries. Background: I am using a cisco 3640 series router running ios 12.4. I am cyclically doing snmpwalks to get the number of bytes transmitted on an output interface for a particular Diff serv code point. The actually snmpwalk call is for cbQosMatchPrePolicyByte (enterprises.9.9.166.1.16.1.1.5) in the CISCO-CLASS-BASED-QOS-MIB mib. My problem. I would like to compute the number of bytes sent per second as quickly and accurately as possible. However I found that the above mib entry can be updated anywhere from 6 to 10 seconds. Sometimes if I poll this snmp entry every 8 seconds the entry hasn't had a chance to change yet and my message rate incorrectly is 0 kbs. My question: 1) Is there somewhere in the mib or cisco's command line interface where I can get the cyclic rate that is being used? Or the timestamp when the MIB entries are being updated? 2) Is it possible to set this rate via snmp or the cisco command line interface and make the router update at a fixed interval of my choosing? 3) Alternatively, Is there a way to generate SNMP traps when router updates its traffic statistics for some DSCP value? Thanks for any inputs, -Proveen ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
Re: [c-nsp] SNMP MIB update interval on CISCO?
On the 6500/7600 platform you can set: service counters max age 5 Obviously this is platform specific. On high CPU load SNMP counters may be updated at a longer interval. At extreme levels SNMP may stop updating completely until the load goes down. Most platforms have a best-effort interval of 10 seconds. As for the accuracy: % Accuracy~=update interval*100/sample interval So with a 60 second sample interval and a ten second update interval you can have a variance of ~17%. With a 5 minute sample interval the variance is ~3%. The accuracy is an approximation as the update interval is best-effort. To sum it up you can sample slower and get more accurate readings or faster and get less accurate readings. -- LR Mack McBride Network Administrator Alpha Red, Inc. Message: 9 Date: Tue, 25 Mar 2008 20:02:23 - From: Dean Smith [EMAIL PROTECTED] Subject: Re: [c-nsp] SNMP MIB update interval on CISCO? To: cisco-nsp@puck.nether.net Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=us-ascii Basically - No. Counters like those are really only valid for polling every minute at a minimum and even then you can occasionally see strange affects due to the internal updates happening out of sync. If you essentially need granularity of a second or so sampling you probably need an external tool. Dean -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gurung, Provin Sent: 25 March 2008 17:02 To: cisco-nsp@puck.nether.net Subject: [c-nsp] SNMP MIB update interval on CISCO? I have a question about how to get the cisco routers updates rate of one of the snmp mib entries. Background: I am using a cisco 3640 series router running ios 12.4. I am cyclically doing snmpwalks to get the number of bytes transmitted on an output interface for a particular Diff serv code point. The actually snmpwalk call is for cbQosMatchPrePolicyByte (enterprises.9.9.166.1.16.1.1.5) in the CISCO-CLASS-BASED-QOS-MIB mib. My problem. I would like to compute the number of bytes sent per second as quickly and accurately as possible. However I found that the above mib entry can be updated anywhere from 6 to 10 seconds. Sometimes if I poll this snmp entry every 8 seconds the entry hasn't had a chance to change yet and my message rate incorrectly is 0 kbs. My question: 1) Is there somewhere in the mib or cisco's command line interface where I can get the cyclic rate that is being used? Or the timestamp when the MIB entries are being updated? 2) Is it possible to set this rate via snmp or the cisco command line interface and make the router update at a fixed interval of my choosing? 3) Alternatively, Is there a way to generate SNMP traps when router updates its traffic statistics for some DSCP value? Thanks for any inputs, -Proveen ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ___ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
