After 4 hours of testing, snooping on a photon that is in fully automatic mode, publishing an event every 5 mins, I have the following data to share:
- Total COAP data transmitted by photon to cloud - 20274 bytes (tcp payload)
- Total COAP data received by photon from cloud - 16434 bytes (again, tcp payload)
- Most COAP packets are 16 bytes of payload, meaning 18 bytes in the tcp payload of that packet.
- TCP header is 20 bytes
- IP header is 20 bytes
- There are additional TCP keep-alives exchanged in each direction approx every 80 seconds (part of the TCP protocol) - these consist of 20 bytes of TCP header and 20 bytes of IP header.
That extrapolates (roughly) to, per day:
Tx COAP data: ~120KBytes
Rx COAP data: ~96KBytes
Total TX IP data (COAP + TCP (incl. keep alives) + IP): ~400KBytes
Total RX IP data (COAP + TCP (incl keep alives) + IP): ~330KBytes
This is without any network sillyness, retries, new TCP connections etc.
Still a long, long way from the 50MB you reported.
I will try and make time to create a SEMI_AUTOMATIC test case, that just publishes every 90 mins. To see if there is any pathological behaviour introduced that way.
Methodology: I use tcpdump/wireshark to dump the packets directly off my wired network between the access point and the firewall. Then inspect/process the resulting pcap files.