Appendix G. Glossary

IXC

IntereXchange Carrier. Phone companies that connect LECs.

kbps

Kilobits per second. 1,000 bits per second.

LAN

Local area network. A group of computers and peripheral devices connected by a communications channel, limited by distance.

leased line

A telecommunication facility or link reserved for the exclusive use of one customer. Also called a ded- icated line.

LEC

Local Exchange Carrier. Provides local access to public data and phone networks.

LED

Light emitting diode. Alphanumeric characters that glow when supplied with a specified voltage.

Link Integrity Poll

A poll that occurs each T391 seconds to determine the state of the connection to the frame relay switch.

LLC2

Logical Link Control Type 2. Upper portion of the Data Link layer (layer 2) that handles flow control and error control.

LMI

Standard published by the Frame Relay Consortium in 1990 to create a defined interface on the UNI. The Consortium was composed of Cisco Systems, DEC, Nortel, and StrataCom, and is commonly referred to as the Group of Four. LMI has become a generic term to indicate the type of frame relay sig- naling used and could be used to mean Annex A or Annex D.

local loop

In telephony the wire pair that connects a subscriber to a phone company end office, typically contain- ing two wires. Four-wire local loops are common, however, especially with leased voice grade circuits.

loopback

A diagnostic procedure where data is sent to the device being tested, and the output of the device is fed directly back to its input, looped around, and the returning data is checked against that which was sent.

MAC Address

Data link address that is unique for every device that gets connected to a LAN. Devices on the LAN use these addresses to update routing tables.

Mbps

Mega bits per second. A measure of the amount of information travelling across a network or commu- nications link.

MIB

Management information base. The MIB is an index to the organized data stored within a network device.

G-6

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