Media converters interconnect different cable types-twisted pair, fiber, and Thin or thick coax—within an existing network. They are often used to connect newer 100-Mbps, Gigabit Ethernet, or ATM equipment to existing networks, which are generally 10BASE-T, 100BASE-T, or a mixture of both. They can also be used in pairs to insert a fiber segment into copper networks to increase cabling distances and enhance immunity to electromagnetic interference (EMI).
Media converters offer an inexpensive alternative to repeaters. They don’t retime the signal or add the signal propagation delays like full repeaters, so they don’t increase the repeater hop count of existing networks. You can use media converters in many applications, but you can’t use them to replace a repeater in cases where you’ve reached the maximum cable distance or the maximum number of devices on a network segment.
Media converters are available in standalone models that convert between two different media types and in chassis-based models that connect many different media types in a single housing.
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Standalone converters convert between two media. But, like a small apartment, they can be outgrown. Consider your current and future applications before selecting a media converter. Standalone converters are available in many configurations, including 10BASE-T to multimode or single-mode fiber, 10BASE-T to Thin coax (ThinNet), 10BASE-T to thick coax (standard Ethernet), CDDI to FDDI, and Thin coax to fiber. 100BASE-T and 100BASE-FX models that connect UTP to single- or multimode fiber are also available.
With the development of ATM (asynchronous transfer mode) and Gigabit Ethernet (1000 Mbps), media converters for these higher speeds and protocols have been created to make the transition to these networks easier. 10BASE-T to coax models convert to either ThinNet with a BNC connector or to standard Ethernet with an AUI connector. 10BASE-T to 10BASE-T models are used to double the 100-meter (328-ft.) distance limitation of a 10BASE-T connection. Many of these converters have an uplink or a crossover switch that enables you to connect to either a 10BASE-T workstation or a 10BASE-T hub without a cross-pinned cable.
100BASE-TX twisted pair to 100BASE-FX fiber models also come in many configurations. Some support either half- or full-duplex operation; some support both. The fiber ports work multimode fiber with ST® or SC connectors or single-mode fiber with SC connectors. ATM and Gigabit modules commonly have SC or ST connectors.
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Chassis-based or modular media converters are normally rackmountable and have slots that house media converter modules. Like a well-planned house, the chassis gives you room to grow. These are used when many Ethernet segments of different media types need to be connected in a central location. Modules are available for the same conversions performed by the standalone converters, and 10BASE-T, 100BASE-TX, 100BASE-FX, ATM, and Gigabit modules may also be mixed. If a switch is used in conjunction with the media converter, all the networks can communicate with each other.