4 Replies Latest reply on Jan 9, 2009 3:36 PM by foroozan

    Report writer (calculating "total bytes transferred" on a Cisco switch interface)

    foroozan

      Does anybody know how report writer in Orion calculates the "total bytes transferred" per month on an interface in a Cisco switch?

      this is my thought:

      if it is using the SNMP to collect the MIB inofrmation from the counter (IN total octet),  then how does it deal with it if the counter gets cleared in the middle of the month?

      if it accumulates the sampling data (every 9 minute or so) then it won't represent the actual total traffic on that interface.

      any help would be appreciate

      Foroozan

        • Re: Report writer (calculating "total bytes transferred" on a Cisco switch interface)
          bshopp

          The total transfer for the month number comes from Orion adding up all of the transfer it has polled for that month. Orion has two ways to deal with counter rollovers, which can be quite frequent (many per day on a busy interface with 32-bit counters). You can toggle between them in System Manager:



          Counter rollover is very rare (the device will reboot more often) when using 64-bit counters, which is recommended if your devices support them.

            • Re: Report writer (calculating "total bytes transferred" on a Cisco switch interface)
              foroozan

              Thanks Brandon for your response. I got my answer regarding the rolover.

              regarding reading the total byte and calculating it within a month I still have a question please. you mentioned that:

              "The total transfer for the month number comes from Orion adding up all of the transfer it has polled for that month."

              when you say "poll" do you refer to the polling interval on the interface (like 9 or 1 minute)? if yes then I would assume that every 9 minutes (for example) it polls the counter ( Do you know which counter?) until it comes to the end of the month and the latest number will be the total byte count, is that right? or if it adds all polling numbers together then it will be a lot more than that actual total number like below:

              first poll on the counter = 100 K

              second poll on the counter=350 K

              the total byte at the second poll will be 350 K but if it adds the two polls together then the total byte will be 450 K which is more than the actual traffic based on the counter.

              Thanks for your advice.

              Foroozan

                • Re: Report writer (calculating "total bytes transferred" on a Cisco switch interface)
                  bshopp

                  These measurements are taken on the statistics polling interval for the interface (default 9 minutes).

                  The counters in question are ifInOctets/ifOutOctets for 32-bit counters and ifHCInOctets/ifHCOutOctets for 64-bit counters.

                  Each statistics polling interval, Orion grabs the value of the counter and subtracts the previous value of the counter (assuming it hasn’t rolled over; see previous discussion). This yields the number of bytes that have been transferred in/out of that interface since we last polled it. This value is recorded in a new timestamped row in the InterfaceTraffic_Detail table in the In_TotalBytes/Out_TotalBytes column.

                  So to compute total bytes received in the last month, we run a query that looks sort of like “SELECT SUM(In_TotalBytes) FROM InterfaceTraffic WHERE DateTime > [one month ago] AND InterfaceID=[the interface in question]”.