The two switches are connected using fiber optic cables

Two switches can be interconnected using fiber optic cables by selecting compatible SFP/SFP+ modules, the correct fiber type, and proper connectors to ensure reliable high-speed communication.

Choosing the Fiber Type

For short distances (under 300 meters), multi-mode fiber (MMF) is typically sufficient, while single-mode fiber (SMF) is preferred for longer distances or future-proofing . Since most inter-switch connections in buildings are short (e.g., 25 meters), multi-mode fiber is usually adequate .

Selecting SFP/SFP+ Modules

• SFP modules support speeds up to 1 Gbps, while SFP+ modules support 10 Gbps. Choose based on the switch port capabilities and desired bandwidth .
• Ensure both switches use compatible modules (same speed, fiber type, and wavelength) to avoid connectivity issues .

Connectors and Cables

• LC connectors are commonly used for multi-mode and single-mode fiber, while SC connectors are less common in modern switches .
• Pre-terminated fiber cables with LC-LC connectors save installation time and reduce errors .
• For redundancy, consider running two fiber cables between switches and configuring them as a Layer 2 EtherChannel to prevent network loops and provide failover .

Configuration Tips

• Use the uplink or SFP ports on each switch for the fiber connection .
• If connecting multiple switches, avoid creating loops unless using Spanning Tree Protocol (STP) or EtherChannel for redundancy .
• Ensure VLANs are properly configured if you need to carry multiple VLANs across the fiber link .

Practical Setup Example

1. Insert compatible SFP modules into the fiber ports of both switches.
2. Connect the fiber cable (LC-LC) between the SFP modules.
3. Configure the ports as trunk ports if carrying multiple VLANs.
4. Optionally, bundle two fiber links into an EtherChannel for redundancy and increased bandwidth. By following these steps, you can establish a high-speed, reliable fiber connection between two switches, supporting LAN/WAN traffic efficiently and allowing for future scalability .