DEC750: can I mix 2.5/5Gbps and 1Gbps link speeds over the SFP ports?

[tonnoplast]

Hello, the DEC750 product description (https://shop.opnsense.com/product/dec750-opnsense-desktop-security-appliance/) has this warning:

When using SFP+Modules, do not mix 2.5/5Gbps and 10Gbps link-speed as the hardware does not support mixing these due to different frequencies.

However it is not clear to me if I can mix 2.5/5Gbps and 1Gbps link speeds on two SFP+ modules. I know I could just use one of the RJ45 Ethernet ports for the 1Gbps link, but I like the idea of just bumping the link speed if I end up getting better hardware.

Thanks!

[lilsense]

If you are talking about the SFP/SFP+, it's highly recommended to have the same on both ends even if one may support various speeds.

So in conclusion, you should never mix SFP/SFP+

[meyergru]

I think this refers to the SFP+ slots not being able to support pure 2.5 Gbps adapters at all.

So, you can use SFP modules with 1 Gbps and SFP+ modules, but only at 1 or 10 Gbps native speeds. To be clear, the modules may support 2.5 Gbps external link speed, but it still appears as 10 Gbps to the DEC750.

I have found no way to support 2.5 Gbps GPON modules at native speed above 1 Gbps.

So, I think that you can use one adapter with 10Gbps and another at 2.5Gbps externally, but they will both report 10 Gbps to the DEC750.

[lilsense]

And you know that causes confusion in all sorta ways! :)

[tonnoplast]

Thanks! But in my understanding the warning I cited in my original post is about not setting up a 2.5G/5G link in one of the DEC750 SFP+ ports, and a 10G link on the other SFP+ port at the same time. So I am not speaking of links ends, but of module usage on the same device.

I'll rephrase my question. On the DEC750, can I use a SFP+ module on one port, and a SFP (= 1Gbps) module on the other port?

[lilsense]

Again, My recommendation is to be identical on both ends.

you can try and YMMV(Your miles may vary)...

[meyergru]

Thanks! But in my understanding the warning I cited in my original post is about not setting up a 2.5G/5G link in one of the DEC750 SFP+ ports, and a 10G link on the other SFP+ port at the same time. So I am not speaking of links ends, but of module usage on the same device.

I'll rephrase my question. On the DEC750, can I use a SFP+ module on one port, and a SFP (= 1Gbps) module on the other port?

I got that. I cannot answer to the question as I have not been able to use native 2.5 Gbps devices at their native speed at all. Having said that, I always had the other slot populated with a 10 Gbps device, so maybe this was the reason. Possibly a 2.5 Gbps device would work actually if not mixed with 10 Gbps in the other slot.

Even if it is so, that does not answer your question of mixing any SFP+ module with an SFP module. Have you asked Deciso to elaborate on the warning?

[tonnoplast]

Thanks again. I didn't directly ask, maybe next week I'll drop them an email.

[meyergru]

Oh, I forgot: You definitely can mix SFP+ 10 Gbps and SFP 1 Gbps in both slots on the DEC7x0: I actually use this with one DAC SFP+ (10GBase-SFI) for LAN and one GPON stick at 1Gbps (technically 1000Base-SGMII) for WAN.

The latter one could even support 2.5 Gbps, but as I said, I never got it running, probably because of the 10 Gbps DAC in the other slot.