calculation error in total_traffic

[simonkurka]

there is a calculation error in total_traffic sometimes as there are suddenly some exabytes transferred. external accumulation of total_traffic works fine.

See the following with the use of total_traffic:
http://server2.sjr-ol.de:3000/dashboard/db/freifunk-templated-with-use-of-total_traffic?from=1463560234247&to=1463571034247&var-server=All

Or this one with external accumulation:
http://server2.sjr-ol.de:3000/dashboard/db/freifunk-templated?from=1463560234247&to=1463571034247&var-server=All