To connect two fiber optic cables through a router, use compatible SFP modules and either fusion or mechanical splicing for the fiber, then configure the routers to communicate over the optical link.

Physical Connection

1. Fiber Type and Modules: Ensure the fiber cables match the SFP transceivers in type (single-mode or multi-mode), wavelength, and distance specifications. For example, single-mode SFPs require single-mode fiber, and the connectors must match (LC-LC, SC/APC, or SC/UPC) .
2. Connecting Fiber Cables:
   • Fusion Splicing: Align the fiber ends and fuse them using heat for a permanent, low-loss connection.
   • Mechanical Splicing: Use a splice holder and mechanical connector to join fibers. This is less expensive but may have slightly higher insertion loss .
3. Pre-Manufactured Patch Cables: For simplicity, you can use pre-terminated fiber patch cables with the correct connectors to link the routers directly via their SFP ports .

Router Configuration

1. SFP Installation: Insert the SFP modules into the SFP ports of each router. Ensure the modules are compatible with the router and fiber type .
2. Network Setup:
   • Assign IP addresses to the interfaces connected via fiber. For point-to-point links, a /30 subnet is commonly used to route traffic between routers without assigning addresses to hosts .
   • Set the default route on the second router to point to the first router's IP on the fiber link. This allows traffic to flow through the primary router to the internet or other networks .
3. Testing and Verification: After connecting the fiber and configuring IP addresses, verify connectivity using ping tests or router diagnostics to ensure the optical link is active and stable .

Additional Considerations

• Distance and Signal Loss: Check the SFP module's maximum distance rating and ensure the fiber length does not exceed it.
• Duplex vs. Simplex: Use duplex fiber for full-duplex communication; simplex may be used for one-way links if required .
• Professional Installation: If running fiber through walls or conduits, consider a trained technician to avoid damage and signal degradation . By following these steps, you can reliably connect two fiber optic cables through routers, achieving high-speed, low-latency communication suitable for extending networks or linking separate network segments.