To configure a 100Mbps fiber port module, ensure the correct SFP type, set the port speed and duplex manually if needed, and verify fiber compatibility and link status.

Key Considerations for 100Mbps Fiber Ports

1. SFP Module Type: Use a 100BASE-FX SFP transceiver for 100Mbps fiber connections. These modules operate over multimode fiber at 1310nm and support distances up to 2km. Ensure the SFP is compatible with your switch model, as using non-compatible or third-party SFPs can cause unpredictable behavior or link instability . 2. Port Speed and Duplex Settings: Some switches default to auto-module or auto-negotiation, which may not always detect the correct speed. For 100Mbps fiber ports, you may need to manually set the speed to 100Mbps and duplex to full using the switch CLI or management interface. This is especially important if the port previously used a different module or if auto-negotiation fails . 3. Fiber Cable Type and Pairing: Ensure the fiber cable matches the SFP type (single-mode or multimode) and that the transmit and receive ends are correctly paired. For WDM SFPs, one side must be configured as the transmitter and the other as the receiver. Incorrect cabling can prevent the link from coming up . 4. Troubleshooting Steps:

• Verify the SFP module is seated properly and recognized by the switch (show interface transceiver or equivalent command).
• Check the link status and logs for errors.
• If the port remains down, try disabling auto-negotiation on both ends and manually configure speed and duplex.
• Ensure the switch firmware supports the SFP module; some older firmware may require manual configuration or a license for higher-speed modules . 5. Hot-Swapping and Safety: 100BASE-FX SFPs are hot-swappable, so you can insert or remove them without powering down the switch. Always follow safety precautions to avoid eye damage from fiber lasers .

Example CLI Commands (Vendor-Specific)

For many switches, the configuration might look like:

configure terminalinterface <fiber-port>speed 100duplex fullno shutdownexit

After configuration, verify the link:

show interface <fiber-port> statusshow interface transceiver

This ensures the port is active and the SFP is functioning correctly. By following these steps—selecting the correct SFP, verifying fiber type, manually setting speed/duplex if needed, and checking compatibility—you can achieve stable 100Mbps fiber connectivity on your switch.