Glossary

Numerics
10BaseT
The 10-Mbps baseband Ethernet specification that uses two pairs of twisted-pair cabling (Category 3 or 5): one pair for transmitting data and the other for receiving data.

B
broadband modem
As used in this manual, a DSL, cable, or long-reach Ethernet modem.

C
cable modem
A modulator-demodulator device that is placed at subscriber locations to convey data on a cable television system.
crossover Ethernet cable
A cable that wires a pin to its opposite pin; for example, RX+ is wired to TX+. This cable connects two similar devices, such as two data terminal equipment (DTE) devices or two data communications equipment (DCE) devices.

D
DRAM
Dynamic random-access memory (RAM). RAM that stores information in capacitors which must be periodically refreshed.
DSL
Digital Subscriber Line. Public network technology that delivers high bandwidth over conventional copper wiring at limited distances. There are four types of DSL: ADSL, HDSL, SDSL, and VDSL. All are provisioned via modem pairs, with one modem at the central office, and the other located at the subscriber site.

E
EMI
Electromagnetic interference. The interference by electromagnetic signals that can cause reduced data integrity and increased error rates on transmission channels.
ESD
Electrostatic discharge. A transfer of electrostatic charge between bodies of different electrostatic potentials, such as an operator and a piece of electrical equipment. ESD occurs when electronic components are improperly handled. ESD can damage equipment and impair electrical circuitry. ESD is more likely to occur with the combination of synthetic fibers and dry atmosphere.

F
Flash memory
The nonvolatile storage that can be electrically erased and reprogrammed so that data can be stored, booted from, and rewritten as necessary.

L
link LNK
A light-emitting diode (LED) that indicates that a physical connection between the router and an Ethernet device exists.
LRE
Long-reach Ethernet. A technology that encapsulates Ethernet packets for robust, high-frequency transmission over telephone wiring, and extends the distance reach from 100 meters for traditional Ethernet over copper to up to 5,000 feet (1,524 meters).

M
MDI
Media-dependent interface. A port on an Ethernet network device used to connect the device to the Ethernet network, usually through a hub or switch.
MDI-X
Media-dependent interface, crossover. A port on an Ethernet hub, such as the Cisco 1528 Micro Hub 10/100, that connects the Ethernet network devices through the MDI port to create a network.
modem
Modulator-demodulator. A device that converts analog and digital signals. At the source, a modem converts digital signals to a form suitable for transmission over analog communication facilities. At the destination, analog signals are converted back to their digital form.

S
SELV
Safety extra-low voltage. A secondary circuit that under normal conditions has a voltage less than 42.4V peak or 60 VDC.
straight-through Ethernet cable
A cable that wires a pin to its equivalent pin. This cable connects two dissimilar devices such as a data terminal equipment (DTE) and a data communications equipment (DCE) device. A straight-through Ethernet cable is the most common cable used.

T
TNV
Telecommunications network voltage. A secondary circuit that under normal operating conditions carries telecommunication signals. Telecommunications signals are a steady-state, varying amplitude, or intermittent voltage or current intended for use on a telecommunications network. A telecommunications network is considered a metallically terminated circuit intended to carry telecommunication signals for voice, data, or other communication. These networks might be publicly or privately owned. They might be subjected to overvoltages due to atmospheric discharges or power-line failures.
TO HUB/TO PC button
A button that enables you to use a straight-through cable to connect either hubs, or servers, PCs, and workstations to the router. Without this button, you would need to supply a crossover cable to connect a hub to the router. Setting the button to TO HUB (in) indicates that you are connecting a hub; setting the button to TO PC (out) indicates that you are connecting a server, PC, or workstation.