The Cisco 100BASE-X Small Form-factor Pluggable (SFP) is a hot-swappable input/output device that plugs into a Fast Ethernet port or slot, linking the port with the network. Hot-swappable when deployed, the switch or router does not have to reboot. Supports the "pay-as-you-populate" model. Interchangeable with other 100BASE-X SFPs on the same line card. Supports the Cisco quality ID feature that enables the switch or router to identify whether or not the SFP is a Cisco qualified SFP. Optically interoperable with respective 100BASE-X Ethernet interfaces on the same link.