[ixpmanager] Spikes on MRTG graphs

[Nick Hilliard (INEX)]

Barry O'Donovan wrote on 28/03/2020 10:38:
> This is exactly as Martin suggests and also how we fix it too.

also, ixp manager puts in spike limits by counting up the total possible 
bandwidth of each individual graph.  E.g. the total possible bandwidth 
of the ixp would be the sum of all the edge ports, etc.  So there are 
checks in there already, but even still MRTG manages to mess things up 
from time to time.

Nick