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. Main features include the following: -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. Cisco 100BASE-ZX SFP The Cisco 100BASE-ZX SFP (part number GLC-FE-100ZX) operates on ordinary single-mode fiber-optic (SMF) link spans up to 80 kilometers long.