Out of band

A piece of hardware used to connect computers (or certain other network devices) together via a serial cable (usually a telephone line). When data is sent from your computer, the modem takes the digital data and converts it to an analog signal (the modulator portion). When you receive data into your computer via modem, the modem takes the analog signal and converts it to a digital signal that your computer will understand (the demodulator portion).
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Highspeed switch that forwards packets between datalink segments. Most LAN switches forward traffic based on MAC addresses. This variety of LAN switch is sometimes called a frame switch. LAN switches are often categorized according to the method they use to forward traffic: cutthrough packet switching or storeandforward packet switching. Multilayer switches are an intelligent subset of LAN switches. Compare with multilayer switch. See also cutthrough packet switching, storeandforward packet switching.
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A piece of equipment that joins a digital phone line to a piece of communication equipment, which may be a phone or a PC. Such equipment allows testing, condition, timing, interfacing, etc. However, it does not do what a modem does: namely, convert digital signals from machines into analog signals which can be carried on analog phone lines. The term “digital modem” is thus somewhat of a misnomer.
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Highspeed, lowerror data network covering a relatively small geographic area (up to a few thousand meters). LANs connect workstations, peripherals, terminals, and other devices in a single building or other geographically limited area. LAN standards specify cabling and signaling at the physical and datalink layers of the OSI model. Ethernet, FDDI, and Token Ring are widely used LAN technologies. Compare with MAN and WAN.
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A remote access, multilayer switch used to connect distant networks over WAN links. This is a strange beast of a device in that it creates WANs, but marketers of this device steer clear of the term WAN and use only the terms LAN and extended LAN. The idea behind this device was to make the terminology easier to understand and thus make the device easier to sell than a more conventional WAN device grounded in complex concepts and terms.
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