Currently the network monitor aggregates all of the network interfaces into a single throughput result.  I use my Internet connection via VPN, so the actual throughput out my physical interface is  doubled since tun0 and eth0 count packets twice: once for the udp tunnel packet, and once for the decapsulated packet received on tun0.  Since tunnel traffic is often compressed, the aggregate bandwidth is sometimes in excess of my actual usage which makes it difficult to estimate without opening iptraf or some console tool.  

It would be great if system monitor could either break out the interfaces (i.e., multiple graphs, or multiple traces per graph / different colors) or simply allow you to choose which interface it is monitoring.  In my general case, I would have it fixed on eth0 and possibly change it to tun0 when I am curious what my current tunnel throughput is.

Thank you for your help!

-Eric

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