Wireshark-bugs: [Wireshark-bugs] [Bug 11295] Incorrect interpretation of IPFIX flowEndSysUpTime,

Date: Thu, 25 Jun 2015 06:56:01 +0000

Comment # 15 on bug 11295 from
In fact, this is different for NetflowV9 and IPFIX.

For NetflowV9 the message header contains sys_uptime and unix_secs (export
time) fields. You can calculate the absolute timestamp of the last
(re-)initialization of the device (boottime) from these values.

The timestamp of LastSwitch and FirstSwitch can then be calculated by adding
msesc to the boottime.

4-7 | sys_uptime | Current time in milliseconds since the export device booted. 
8-11 | unix_secs | Current count of seconds since 0000 UTC 1970.

However, for IPFIX the message header contains only Export time, which is
equivalent of V9's unix_secs. The boottime must be retrieved from the
systemInitTimeMilliseconds field.

21 | flowEndSysUpTime | The relative timestamp of the last packet of this Flow.
It indicates the number of milliseconds since the last (re-)initialization of
the IPFIX Device (sysUpTime). sysUpTime can be calculated from
systemInitTimeMilliseconds.

22 | flowStartSysUpTime | The relative timestamp of the first packet of this
Flow. It indicates the number of milliseconds since the last
(re-)initialization of the IPFIX Device (sysUpTime). sysUpTime can be
calculated from systemInitTimeMilliseconds. 

160 | systemInitTimeMilliseconds | The absolute timestamp of the last
(re-)initialization of the IPFIX Device.

But I can see that the value for me is not worth the effort, so I think you can
leave it as it is.


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