SFP Connector usage?


Curious to know if you could use the SFP connector for the connection to a switch on your LAN, as opposed to the connection for the WAN? I can’t see (at least in the United States) many residential users being able to make a direct fiber connection with their ISP. The next best use case I can think of would be to use it on the internal LAN to feed the switch stack I am using.

Thanks, just wondered if anyone knew.


Switching the SFP port to LAN may not work for Foris (Turris Omnia’s web interface) but will work for LuCI (OpenWRT’s native web interface). Both web interfaces are available at the same time.

WAN ethernet will get disabled if you use the SFP port. You may use any LAN port for WAN. LAN5 would be my suggestion.

The hardware and OpenWRT are both capable of this. The limit may be security concern about switch config on bootup and the need to edit config files manually.

I think I may be able to hook the Omnia onto my WAN directly (but I am way to inexperienced to do so). Will there be any official instruction (for dummies) / community wiki on doing that?

I am not sure, this is correct.The LAN ports collectively is a piece of hardware switch. I don’t think they are individually configurable other than vlan.

The way it would work is:

  1. Create 2 separate VLANs on the hardware switch
  2. Software bridge the SFP port to one of the VLANs and use this as your LAN device
  3. Use the other VLAN as the WAN device

The switch is quite capable and supports something extra using the dsa driver. I won’t take this into account for this. It would enable to have every ethernet port as a real eth device in linux.

The rest is based on the OpenWRT swconfig style configuration.

The SoC has 3 ethernet devices. eth0 to eth2.
I assume eth0 goes to switch port 5, eth1 to port 6 and eth2 is WAN.

The switch has 7 ports. 2 are connected to the SoC. 5 are available as LAN1 (port0) to LAN5 (port4).

The third ethernet port is connected to the WAN interface. It is switchable between copper and SFP.

config 'switch'
        option 'vlan0' '0 1 2 3 5'
        option 'vlan1' '4 6'

Then you have eth0 as LAN and eth1 as WAN.
If you add eth0 and eth2 to you lan definition in OpenWRT you got what you wanted.
No VLAN tags in software involved.

The bridge will for most users already be there for the Wifi interfaces so no new bridge.

Edit: This config may even be better. The SFP port should be able to support 2.5GE so adding a SFP module would possibly allow connecting a 2.5GE switch or device like your shiny new server or something like that.

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Which config are you referring to in your edit?