Hmmm...you should be able to adjust this 20-30s interval, but the way it is right now, each one of those is a packet, so two packets at each exchange. A packet is +/-1500 bytes, so about 3000 bytes per exchange. If you have two exchanges each minute, that's 6000 bytes per minute or 360000 bytes per hour or 8640000 bytes per day. There's 1048576 bytes in a megabyte so 8.23974609375MB per day or 57.67822265625MB per week.
Now, when looking at your log, it's doesn't look like every 20-30s, but every 2-3s. :O That would make all these calculations 10x too small. 80MB+/day and 570MB+/week would then be right--and that's just waaaaay too much ack/nak chatter going on.
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