Graphing difference between two intefaces?

[AdrianChadd]

I'd like to graph the differences, in/out, between two interfaces. I've not had any luck defining a graph template which I can specify two traffic_in and two traffic_out data sources.

Does anyone know of a way to do this?

Thanks!

[gandalf]

It is possible to create a graph template for this, but you may not be able to associate it to a host as usual.
Perhaps it would be better to create a "New Graph" from "Graph Management" in the first step for the host. Add those 4 data sources that you need (for the specific interfaces of that host). Switch DEBUG mode on and post the "rrdtool graph" statement. Then lets build the CDEFs together
Reinhard

[AdrianChadd]

Just a follow up - i pulled apart a few examples and did figure it out. It required a little math to get the cdef's in the right place for a subtraction operator to kick in and graph the difference of in/out.

Thanks though!