Beginner Attempt at Fiber a Fail - Help Needed

Hardware MikroTik hardware general
1

I’m a complete newb to fiber optic. I’d like to connected a hAP ac (RB962 router running ROS 6.49.15) and a CSS610 switch (running SWOS Lite 2.18) using SFP modules and a fiber optic cable in between. I tried but I can’t get it to work properly.

I bought two 1.25G 1000Base-SX 850nm MMF SFP modules: https://www.amazon.com/gp/product/B01M0UKAQD and a duplex LC-LC MMF patch cable: https://www.amazon.com/gp/product/B089JWXPY9. Both the hAP ac and CSS610 seem to recognize the SFP modules okay and the TX/RX signal strength is good (going from memory, around -6dB or better).

With auto negotiation enabled on both ends, no link is ever established. On the hAP ac side, the “rx lose” checkbox will have a check mark flashing when auto negotiation is turned on. If I turn off auto negotiation and manually force a 1000M connection on both ends, the “rx lose” checkbox in the hAP ac stays off and a link is briefly established, then dropped, established, dropped… flapping indefinitely.

Is there something obvious I’m overlooking?

Note: The hAP ac router has a 1000M capable SFP cage, while the CSS610 has two 10G capable SFP cages. In searching the forums here, I saw someone mention that trying to use a 1000Base SFP module in a 10G cage can be problematic. Could that be it?

Thanks,

John

2

I know that ROS doesn’t like some SFP modules. I’ve had issues with Arista modules for example.

But start at the simplest - the fibre itself. If you can get a spare fibre somewhere to test with?

You could also try cleaning the fibre tips, even though they should be clean as they’re new - there could be some residue on them.

3

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

I have not used this sfp module, (or the css switch), but I find on their routers, using 1G base X is a good choice for connectivity.

Also there have been a lot of sfp fixes, you might want to try a recent v7. (with an updated routerboot)