I have a Mikrotik CRS305-1G-4S+IN 5 Port Desktop Switch. I need to use it to convert a SPF+ 1G fibre port to RJ45 copper between two local fixed IP addresses.
I have a host (IP 192.168.0.100) and a client (IP 192.168.0.101) that need to communicate using TCP/IP. I have an existing copper unmanaged switch that I connect these two devices using copper RJ45 and I can establish comms and it all works (a BrainBoxes SW-005).
I did the same using an SPF+ fibre (1GB OM3 LC interface) plugged into port 1, with my computer (the host 192.168.0.100) on the PoE RJ45 port. I was expecting them to connect. But they don’t.
I have tried to grapple with the documentation, but I’m a hardware engineer and have little comms experience.
By default, CRS devices are configured to act as switches between all ports. So the problem you’re experiencing is most probably not configuration error.
I don’t have a CRS305, but I believe that the RJ45 port is intended for management. Thus it might not be part of switch ports group.
Mikrotiks are quite notorious for sub-optimal support for SFP modules. And if they are supported, speed autonegotiation might not work. So verify these things:
is SFP module detected and recognized?
did port speed negotiate to 1Gbps (you’re writing about 1Gbps all over so I’m assuming the optical link peer supports 1Gbps and not 10Gbps).
If it didn’t, try to disable autonegotiation and set speed to 1Gbps
If you’re using SFP+ RJ45 module to connect the copper device, repeat the steps written above also for the RJ45 port.
As you run the SFP+ port at 1G (and so probably are using an SFP): did you disable autonegotiation and set the port to 1G FDX? If you don’t, the link will seem to come up, but no traffic will flow. Been there, done that…