How does ceilometer accumulate network stats?
Hello. How does tracking for total bytes received/transmitted work?
For a given network, there are nova meters for network.[incoming|outgoing].bytes. Does the data for these come from ethernet frames (e.g., the data that shows up when running ifconfig) or IP packets (e.g., the counters in iptables)?
How is this data made cumulative? By storing it in the backend db, or by relying on, say, persistent iptables counters?
What exactly is measured? Is it accumulated bytes/packets (where the network device is doing the accumulation), or a sample since the last time the collector was run (where the network device counters are zeroed out each time by the collector) followed by addition to the value already stored in the backend? Or does it work some other way?
I'd like to set up metering for specific network traffic (e.g., for specific nova compute agents; for specific protocols; etc.) and I'd like to follow a ceilometer-centric way of doing this, either via using ceilometer itself or via an existing monitoring solution (nagios). I need this better understanding of how ceilometer accumulates network data to make that decision.
Thanks in advance for your help.