To configure a two-port fiber optic connection, you need compatible SFP modules, duplex fiber cabling, proper port configuration, and VLAN setup on both switches.

Step 1: Verify Hardware Compatibility

Ensure both switches have SFP or SFP+ ports available. Select SFP modules that match the fiber type and network speed:

• Multimode fiber for runs under 1000 feet
• Single-mode fiber for longer runs
• SFP modules must match the switch's supported media type (SX, LX, ZX) and bandwidth (1G, 10G, etc.), .

Step 2: Prepare Fiber Cabling

Use duplex fiber optic cables with LC connectors. Ensure the cables are terminated correctly and clean to avoid signal loss. When connecting two switches, cross the send and receive strands: the transmit (TX) of one switch connects to the receive (RX) of the other .

Step 3: Insert SFP Modules

Insert the SFP modules into the corresponding ports on each switch. Most SFPs are hot-swappable, so the switch does not need to be powered down . Verify the module type matches the fiber cable (single-mode SFP with single-mode fiber, multimode SFP with multimode fiber), .

Step 4: Configure Switch Ports

Access the switch via console or SSH and configure the fiber ports:

1. Enable the interface: interface GigabitEthernetX/X or interface TenGigabitEthernetX/X
2. Set the port to no shutdown: no shutdown
3. Configure speed and duplex if required (most SFPs auto-negotiate)
4. Assign the port to a VLAN if needed: switchport mode access and switchport access vlan <VLAN_ID> .

Step 5: Verify Connectivity

Check the link status with:

• show interface status
• show ip interface brief
• Ensure the link lights on the SFP ports are active. If not, verify SFP compatibility, fiber type, and cabling .

Step 6: Save Configuration

Once the connection is verified, save the configuration to the switch's memory: copy running-config startup-config .

Troubleshooting Tips

• No link light: Check SFP type, fiber type, and strand orientation.
• Third-party SFPs: Some non-Cisco SFPs may not work with Cisco switches.
• VLAN issues: Ensure both ends are in the same VLAN if using access mode, or configure trunking if carrying multiple VLANs . By following these steps, you can establish a reliable two-port fiber optic connection between switches or from a switch to a fiber network, ensuring high-speed and stable communication.