You can use a fiber optic media converter or switch with SFP support to connect a Gigabit Ethernet network to a 100Mbps fiber link.

Media Converters for Speed Conversion

Industrial-grade media converters like the DS201 allow you to connect a Gigabit copper Ethernet port to a fiber optic link that supports either 100Mbps or 1000Mbps via SFP modules. The device can automatically detect and adjust to different speeds or duplex settings between copper and fiber, and it supports low-latency converter mode or store-and-forward switching mode. Features include Link Fault Pass-Through, jumbo frame forwarding, and wide temperature operation (-40°C to 75°C), making it suitable for industrial environments .

Fiber Optic Switches with Mixed Speeds

Fiber optic switches from vendors like Versitron or Byxgd provide multiple RJ45 and fiber ports and can handle 10/100/1000Base Ethernet simultaneously. Many switches support SFP modules, allowing you to insert a 100Mbps fiber SFP on one port while maintaining Gigabit copper connections on others. Managed or unmanaged options are available, and some models include PoE support for powering devices over Ethernet .

Key Considerations

• SFP Compatibility: Ensure the switch or converter supports 100Mbps SFP modules if your fiber link is 100Mbps.
• Auto-Negotiation: Devices like the DS201 can automatically adjust speed and duplex between copper and fiber.
• Industrial vs Commercial: For harsh environments, choose industrial-grade devices with EMC protection and wide temperature ranges.
• Mode Selection: Some converters allow switching between low-latency converter mode and store-and-forward mode depending on your network requirements.
• Power Reset: Changing SFP modules or DIP switch settings may require a power cycle to activate the new configuration .

Recommended Approach

1. Identify the fiber type (single-mode or multi-mode) and required distance.
2. Choose a media converter or switch with SFP slots that support 100Mbps fiber modules.
3. Connect your Gigabit Ethernet devices to the copper ports and the 100Mbps fiber link to the SFP port.
4. Configure the device for auto-negotiation or fixed speed as needed. Using this setup ensures seamless communication between Gigabit Ethernet networks and 100Mbps fiber links, with options for industrial reliability, PoE, and flexible port configurations.