graph.php showing zero agregate bps value for now in multi-port_bits* graphs

This is definitely fixed.

http://demo.observium.org/graph.php?type=multi-port_bits_duo_separate&id=1072&idb=1173

I performed update  to 9701 and I see your fix with ADDNAN, but aggregate graphs still have zero value for Now. 

This was apparently added in 2008, 2 years after i wrote the first graphs!

Aha. Apparently there is a special operator for this, because 1 + UNKNOWN = UNKNOWN, so they have a special operator where 1 + UNKNOWN = 1.

It should behave better fin 9701.

(this is literally a 12 year mystery solved!)

I don't think it's even a bug, I think it's a limitation in how rrd stores data. We're showing the "LAST" value of the aggregate of IN+OUT, and it seems that for half of the time period, this isn't populated and returns zero (because the data hasn't been polled yet).

I'm not sure if there's some strategy to counter this. I recall fiddling with it a few times.

Looking at it further, it's because we set "unknown" values in the rrd data to zero when graphing, because otherwise any unknown value in the data completely breaks the aggregate (a single down port in a graph of 100 will set all values to unknown).

So this is only problem of aggregate graphs and it's caused by some bug in rrdtool. Have you tried to report this upstream ?

This is caused by rrdtool being useless. I'm not sure of the exact reason, but I think it's because it is wanting to aggregate the NEXT period instead of the current one.

It's been annoying for many years, and we don't find a solution for it.