I cant make heads or tails of the stats (Rx Bytes and Tx Bytes) I get from my two MikroTiks CSS326-24G-2S.

At first I couldn't explain some of the traffic in several ports and started to keep a record.
Then according to my records, the traffic in some of the ports decreased from one day to the other, by as much as 3GB.

As far as I know these aren't daily records, but accumulated over time, and there is no way to reset the count for just one port.

This are the records I have kept for the last three days :

NB. Delta 1d is the difference with the previous day. Last data are taken 8 days from the last reset of the counters.


Is this a bug or have I got something completely wrong ?

You are sure you are reading 64-bit values and not 32-bit which will wrap around when exceeding 4GB?

I'm reading these two here. Not sure if they are 32/64-bit.
If there is a wrap around at 4GB, it could explain it completely. Is there another way to keep an eye on traffic using SwOS ?

Of course you would use SNMP for that, but there are 32-bit and 64-bit values.
It may also help when you update the OS as quite a common fix listed in those release notes is to make those values 64-bits.

do you have the latest version of SW os?

SwitchOS 2.7 and below used 32 bits for the stats. Real easy to roll over. VERY likely what you are seeing. According to the release notes for 2.8 (just released) one of the changes:
*) use 64bit counters under Stats tab for byte accounting;

How do I use SNMP to connect to SwOS ?

I was on SwOS 2.0 until now, and just upgraded one of the switches to 2.8. I will report back if the counter goes indeed beyond 4GB now.

Thx to all, I didn't think this would be solved.

It's confirmed. The reason was a wrap around at 4GB because of a 32bit variable for the counters. In SwOS 2.8 it becomes 64bit and the counters make sense now.
This was really helpful.

Happy I could help.