Question about SFP ports compatibility

[AdmIT]

Hello,

 I'm changing my old D-Link DGS-3120-48TC switch to Cisco SG300-52P switch and the only thing I'm not sure are SFP ports. Is there any way to check if my old SFP d-link modules will be fine for Cisco SFP ports? Are there any differences between them and will it work with other D-Link switches? Eventually, I will change them too, just not in one shot. With one brand it was easy to choose and I didn't have to learn more about, so I'm not sure if there is a standard and all ports are the same and all SFP modules will work fine, or I have to buy specific modules for specific switch brand.

Thank you in advance for your answers!

[Joseph W. Doherty · Accepted solution]

Not sure about the SG series, but most Cisco Enterprise network devices, by default, will only work with Cisco SFP modules (which are often specific to a device with a certain IOS level). There is a hidden command, on many Cisco Enterprise devices, to allow them to work with non-Cisco modules, and they often will, but sometimes they don't and if you have issues, Cisco will not support trying to get them to work.

You can try them though, and if they work consider yourself lucky. It also helps if the non-Cisco vendor guarantees they will work with Cisco equipment.

[AdmIT]

Thank you, Joseph! I have one additional question just to be 100% sure- When I tag some VLANs to this SFP port with Cisco SFP module dedicated to this model, there shouldn't be any difference to which device the traffic is sent?

I mean, traffic is traffic and it should work just fine with Cisco -> D-Link with its SFP modules? They should communicate without any issues, right?

[Joseph W. Doherty]

Yes, in that regard a port with a SFP is just another Ethernet port, it "logically" doesn't care what kind of module your using. (Whether the module will come up and work with the other side, though, is a L1 compatibility issue. It's much similar to a copper Ethernet port, logically, it doesn't care what kind of "CAT-#" cable you're using.)

That said, when working with mixing Cisco and non-Cisco equipment, at L2, you can bump into some issues like untagged frames (i.e. native VLAN) on Cisco trunks and/or STP issues as Cisco equipment defaults to using per-VLAN STP and most other vendors support a common/global STP, etc. (I.e. Cisco and non-Cisco equipment don't always play well together, even when they can send frames back and forth once you move beyond the most basic L2 configuration.)