short connection interruptions at KSZ9896
I use the switch KSZ9896. My devices consist of a switch and a CortexM3-MCU connected via RMII/IIC. All devices hang in a daisy chain and receive mainly unicast UDP packets (traffic about 100kByte/device). Loops and time delays are no problems. I also entered the entries from the document "Silicon Errata" (it's a pity that almost all entries in the datasheet are undocumented and not traceable).
It works quite satisfactorily with two test setups of 20 and 10 devices.
Now to the problem: In irregular intervals (between 2min and 2h) the link seems to disappear at random places of the chain. I monitor the link state via the "PHY Basic Status Register" and/or the "PHY Digital PMA/PCS Status Register" of the KSZ9896. With the first one I also pay attention to the "Latch Low" function and read twice. If the link status changes for more than one second, my devices send a status message.
The disconnections are mostly short (probably about one second for auto-negotation) but still visible. Sometimes the connection stays away completely.
- Is the behavior known or has it occurred in a similar way before somewhere?
- If so, how can the connection breaks be eliminated?
- or is there a way to find out what caused the connection to fail?