Traffic graph shows negative bandwidth

[quazik]

I regularly see "dips" in the traffic graphs as shown in the attached image that seem to indicate negative bandwidth use.  I think it's purely cosmetic, a glitch in the graph generation, but it's annoying.  Any thoughts on what's happening and is there a fix available or in the works?

TIA

[cmb]

On a 32 bit OS that comes from a 32 bit counter, that's what happens when the counter wraps.