Network media converters are used to interconnect different types of cables within an existing network. They receive data from one type of cable and convert the signals for transmission along another cable type. Typically, network media converters are often used to connect newer Gigabit Ethernet (1000 Mbps) cabling to older 10Base-T or 100Base-T networks. Some network media converters are standalone devices that convert data between two different media types. Others are chassis-based models that connect many different media types in a single housing. Generally, these chassis-based devices are modular, stackable, and rack-mounted. They may also include an uplink or crossover switch to allow connections to either a workstation or a hub without the use of a cross-pinned cable. Network media converters with an integrated circuit (IC) or printed circuit board (PCB) form factor are also available. Full-duplex converters can be connected to network devices that transmit and receive signals at the same time.
Network type is the most important consideration when selecting network media converters. Common network types include asynchronous transfer mode, Ethernet, token ring, optical carrier, single mode fiber, and multimode fiber. Asynchronous transfer mode (ATM) is a network technology that transfers data in cells or packets of a fixed size. Ethernet is a common local area network (LAN) protocol that uses a bus or star typology and supports data transfers of 10, 100, or 1000 Mbps. Some Ethernet networks use 10Base-T, 10Base-2, 10Base-5, 10Base-FL, 100Base-T, 100Base-TX, or 10/100Base-TX cabling. Others use 1000Base-CX, 1000Base-LX, 1000Base-SX, or 1000Base-T. Token ring is a network transport typology in which attached devices must receive a supervisory frame or token before they can transmit data. Optical carrier (OC) is a protocol that specifies the speed of fiber optic networks which conform to the synchronous optical network (SONET) standard. OC-3 has a standard speed of 155.52 Mbps. OC-12 has a standard speed of 622.08 Mbps. Single-mode fiber has a narrow core that allows light to travel along in only one path. By contrast, multimode fiber has a relatively wide core that allows light to travel in multiple rays along different paths. Serial communication types for network media converters include RS232, RS422, and RS485.
Selecting network media converters requires an analysis of port connectors. Attachment unit interface (AUI) connectors are often used to connect Ethernet network stations and transceivers. Subscription channel (SC) connectors are medium-sized coaxial devices with a frequency range of 0 - 11 GHz. They are larger than Bayonet Neil-Concelman (BNC) connectors, devices which have a slotted outer conductor and a plastic dielectric that causes increasing losses at higher frequencies. Single-mode and multimode straight tip (ST) connectors feature a quick release, bayonet coupling that requires only a quarter turn to engage or disengage. RJ-45 connectors are similar in appearance to standard phone connectors, but are twice as wide with eight wires. Single mode and multimode MT-RJ connectors feature a compact, RJ-style design but hold two fibers with a single ferrule. Medium interface connectors (MIC) are duplex devices used in fiber distributed data interface (FDDI) networks. DB-9 connectors are also commonly available.