820s, FCS errors and CCRs

Is anyone seeing FCS errors with 820s plugged into CCRs on copper? Don't see these on the 4011s and 3011s.

Different firmware on both the Mikrotik CCR and the 820 produce the same results.

Hi, I'm not sure if this exactly matches your issue, but common FCS errors are due to port negotiation mismatch, frame size support and, in the case of the PTP820, surge suppression.

I would double-check that the port negotiation is happening properly on both ends of the cable, that the PTP820S is configured for a high enough frame size (PTP820 supports jumbo frames, but is set to max MTU/MRU size of 2000bytes - you can change from the Ethernet>General page), and that the correct surge supression is being used (more below).

Surge Suppression is recommended when using a lower grade POE or when in a high static environment.  This post goes into detail about the specifics of grounding.  However, the surge suppressor called out in these posts (C000000L033A Gigabit Surge Suppressor (56V)) should only be used when current is flowing through the cable (i.e. POE).  If you are powering direct DC, or using other data ports for just data, no power (i.e. MGMT), a third party surge suppressor (ALPU-F140) is recommended.  Using the C000000L033A Gigabit Surge Suppressor (56V) on cables without POE may cause bit errors on the link.

Hi J2sw,

We have experienced FCS erros with 820S connected to CCR1036-12G-4S. After troubleshooting connectors, cables and PoEs, we discoved the problem was with the Cambium Gigabit Surge Supressor (56v) (C000000L033A). As soon as we removed it, the FCS errors were gone. 


Currently this happens with no surge suppression. It does not happen with a 3011 in the middle. Leads me to believe the switch chip in the CCR might not be happy with the 820. However, that is not the answer.