Can SFP cause the problem that I have or something else?

[dule020]

Hi everyone, I recently became the owner of a MikroTik RB5009 (non-PoE version). The main reason I bought it is because I wanted to have both my fiber and local network go through a single device — meaning I didn’t want to use a media converter anymore, but instead have the MikroTik handle everything by itself.

Here’s how my internet setup works: My ISP assigns me an IP address, gateway, and DNS servers. On their end, they scan for my device’s MAC address, and once that matches with the configuration on their side, I get access to the internet.

The media converter I currently have is an Extralink Luna V3 (hopefully soon everything will be MikroTik). We use a single fiber line with an SC connector (blue) — so it’s a single-fiber setup.

I bought the RB5009 and the following SFP module: Extralink EX.6204 SFP 1.25G 1310/1550nm 20km LC DOM. I received two units — one blue and one yellow. The yellow one (1550/1310) doesn’t provide any signal response at all.

I also purchased a short cable that goes from SC to LC, since the SFP uses LC connectors. I chose Extralink because the media converter was also Extralink.

Now, here’s the issue: In MikroTik, the SFP interface shows link up, meaning it detects the signal, but I’m not getting any packets. I can see TX and RX counters — TX is working, but RX stays at zero. It’s strange because the device detects both transmit and receive signals, yet there’s no communication happening — no data exchange.

When I configured the MikroTik, I made sure all interfaces were set up correctly with the SFP as WAN, but the ISP still couldn’t see my MAC address. I also set the SFP interface under Interfaces → Interface List → WAN, but that didn’t change anything either.

I have a feeling it’s something small — some little detail I’m missing. I noticed the SFP port is set as a slave port by default — could that be the reason? Ether1 isn’t part of that group though. I’m not sure how to remove it from being a slave if that matters.

In the end, I reconnected the media converter again, plugged it into ether1, set everything up there, and it worked — the ISP immediately detected my MAC address and gave me internet access. But that means I still have the media converter in front of the MikroTik, which I really want to avoid.

Could the problem be with the Extralink SFP itself — maybe it’s not receiving signal properly? Although, what confuses me is that it does detect signal levels correctly in dBm, so I’m not sure if it’s a configuration issue instead.

Maybe it’s something in the firewall or some other setting I’m overlooking? Any advice on what to try next would really help.

Essentially, the SFP has a different MAC address — so if that’s the issue, I can easily clone the working MAC address from ether1 (they differ by just one character). I just need to get the connection working first — after that, I can update the ISP on their end if needed.

[CGGXANNX]

You purchased the wrong SFP stick, and should return it if it's still possible!

Your Extralink Luna V3 appears to be an EPON ONT device. If you want to replace it by an SFP module, you'll need to purchase an EPON compatible ONU SFP, not that Extralink EX.6204. You can either buy sticks that says EPON ONU, or one of those marketed as XPON ONU (but not XGSPON!!!) that are dual-mode compatible with both GPON and EPON. Anyway, you must make sure that the module supports EPON in its specs.

[CGGXANNX]

And yes, once you've purchase the correct SFP stick, then if you are using the defconf default configuration that comes with the RB5009, you'll need to make some modification to the bridge setting.

By default, the sfp-sfpplus1 port is configured as member of the main bridge, and is a slave port of that bridge. You have two choices:

• The easier one is to move that port out of the bridge, by simply going to the Bridge -> Port table in WinBox and click "Disable" on the sfp-sfpplus1 entry. The port will become a standalone port, like ether1 in the defconf. Here you can also add ether1 to the bridge to use it for your LAN needs (because you don't use it for WAN anymore).

• An alternative is to keep sfp-sfpplus1 in the bridge, and even put ether1 in the bridge too, so that all ports are in the single bridge. This suits the way the ports and switch chip are wired on the RB5009 very well. because all ports are connected to the switch chip that has full hardware offload for VLAN filtering. You then configure Bridge VLAN Filtering on the bridge, and make sfp-sfpplus1 the access port of one VLAN for example VLAN 1000 (by setting pvid=1000 and set frame-types=admit-only-untagged-and-priority-tagged). Create a VLAN interface with this ID 1000 under /interface vlan. And you can use this VLAN interface as your WAN interface instead of sfp-sfpplus1. This is the configuration I am using on my RB5009:

  Examples

  

  

[dule020]

Thanks for replying.

If you have some to suggest that maybe you used sometime ago, please let me know here or PM