So I have an extra CSS610 lying around and decided to use it instead of the CRS310. Installed two SFP+ RJ-45 transceivers on the new CSS610, one for connecting to the old CSS610 (@10G) and the other to connect the Linux box (@2.5G). Starting with fresh SwOS configs on both, only change was to enable Flow control on all connected ports.
The first iperf3 run between the Linux box (on the new CSS610) and pfsense (on the old CSS610) resulted in 100k+ TX Pauses generated on the old CSS610 (where pfsense is connected) and 2 (LOL) RX Pauses on the new one (where the Linux box is). I’ve repeated the test 20 more times and I can only get the downstream to generate TX 100k+ pauses, no more RX pauses registered on the uplink.
I’m starting to understand what other were referring to when they said Mikrotik devices are tricky to set up ..