Fiber Optic Question about Single Mode cable with SC connection on SFPs

Question

I have two places to connect. Let's call it, place A and place B.

On place A there is a Fortigate100D which has this kind of port;

On place B there is a Cisco SF200-48 10/100 Smart Switch;

I have made the 1km cabling with this cable;

I think the cable is Single-Mode and the termination should be with SC. I also probably need an SFP device, but as I searched, I should use 1000BASE-LX for single mode fiber. The question is I didn't see any SFP device with 1 SC connection. I am perplexed right now and need some help.

Answer 1

The yellow cable indicates single-mode fiber which is also necessary for a reach of more than a few hundred meters. The usual Gigabit Ethernet PHY for this is 1000BASE-LX, you're correct. (It's actually 1000BASE-LX10 for 10 km reach, the original 1000BASE-LX with 5 km reach is pretty much obsolete. You could also use 1000BASE-BX10 with single strands.) From the photo, the fiber is unterminated.

SFP modules use LC connectors as SC is too large to fit. Many fiber panels terminate with SC jacks, so you use SC-to-LC patch cables. Make sure you get single-mode patch cables as well.

LC versus SC duplex connectors (pictured with orange OM2 cable which is not what you need)

When buying transceivers, watch out for their brand compatibility - most devices only accept correctly branded transceivers: in your case Fortinet on the one and Cisco on the other side. The transceivers don't necessarily need to be original vendor's, there's a large market of compatible modules.

On the FGT-100D, note the shared TP/SFP ports - port 15 is already in use with twisted pair, so you'll need to use port 16.

Answer 2

I think the cable is Single-Mode

Looks like your cable is single mode (yellow jacket generally indicates singlemode) and has four fibers in it.

and the termination should be with SC.

Or LC.

Either way when terminated there will be four connectors on the end of the cable, one for each fiber. These connectors may or may not be joined into pairs using clips.

I also probably need an SFP device, but as I searched, I should use 1000BASE-LX for single mode fiber.

1000BASE-LX (or LX10 which is basically the same, just with a longer maximum range) runs over a pair of single mode fibers, so your transciever will have a pair of connectors on it. You also get 1000BASE-BX which runs over a single strand of single mode fiber.

Note that it is necessary to cross over transmit and receive between the two transceivers. With LX this is done by crossing over the fibers. With BX this is done by using an "upstream" transceiver at one end of the link and a "downstream" transceiver at the other.

The question is I didn't see any SFP device with 1 SC connection. I am perplexed right now and need some help.

Due to space constraints SFP modules use LC rather than SC connectors.

I don't have any fiber patch panels and if there is a chance to connect without patch panel I will go for it.

A patch panel isn't absolutely essential but it is generally considered a very good idea. The individual strands of infrastructure fiber have very little protection while patch cables have separate Kevlar reinforcements for each individual fiber. A fiber patch panel should provide a place to secure the reinforcement of the infrastructure cable and then provide protection for the individual fibers as they pass to the couplers on the front of the patch panel.

The patch panel also means that if/when in the future you change to equipment that has different connectors you can simply replace the patch cord.

I am going to buy sockets and SFPs after I am sure about the right tools.

My advice would be to get the termination of the fiber done by a specialist and let him supply the connectors and patch panel. Learning to terminate fiber is a specialism in itself.