CRS510-8XS-2XQ SFP GE transceiver in SFP28 port

Hi all.

I have been unable to get my CRS510-8XS-2XQ to switch traffic between two devices. I am running ROS 7.15.

I have two devices hanging off of it (A and B). Device A connects via a 100G Mikrotik DAC on QSFP28-1 which is confirmed to receive traffic (i.e. ICMP packets originating from A are being received at the Mikrotik port). Then I have another device B hanging on SFP28-1 which is confirmed to receive the (internal) traffic forwarded by QSFP28-1. However, the traffic is never delivered external to endpoint B. TX packets is 0. The SFP I’m currently using is a 10Gtek ASF-GE-T which, theoretically, should work. I have disabled auto-neg and set the speed to 1G baseT. (I’ve also tried 1G baseX and auto-negotiation as well just to make sure.) I recently upgraded to 7.15 because I was encountering a TX-fault indicator which 7.15 has corrected.

All ports are members of the same default bridge (I’ve tried creating a new bridge, to no use). This is about as vanilla a setup as it comes. The 1GbE network card on my endpoint B is supposedly working (green link light). The link on the Mikrotik is lit as well. I’ve swapped SFPs (two different brands), ports, cables.

I must be missing something fundamental here. I was under the impression that SFP28 ports on the Mikrotik were capable of operating at 1G with an SFP when explicitly configured as such.

There have been other questions about the 10GTek device, perhaps this might help.

http://forum.mikrotik.com/t/10gtek-sfp-module-ref-asf-ge-t-auto-negotiation-problem-with-routeros-7-12/174766/4

Thanks for this.
The “ignore rx LOS” was available only after I upgraded to v7.15 and I did try it, to no avail, unfortunately.
I think my problem might stem from an SFP transceiver in an SFP28 port. I thought that was supported as long as auto-neg was disabled.