Medias Mediatrix 1204, Справочное руководство

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Appendix E - Glossary Layer 3
342 Mediatrix 1204
Logical Link Control (LLC)
Layer 3
Layer 3 refers to the Network layer of the commonly-referenced multilayered communication model, Open
Systems Interconnection (OSI). The Network Layer is concerned with knowing the address of the
neighbouring nodes in the network, selecting routes and quality of service, and recognizing and forwarding to
the transport layer incoming messages for local host domains.
Light Emitting Diode (LED)
A semiconductor diode that emits light when a current is passed through it.
Local Area Network (LAN)
Data-only communications network confined to a limited geographic area, with moderate to high data rates.
See also WAN.
Loop Start
Your average telephone line uses the loop start method of signalling. When your telephone is on hook, no
current is flowing on the line. When you take your telephone line off hook, the current flows and this is detected
at the other end as a voltage drop. Loop start signalling only works for supervision one way. In other words,
because loop start signalling is based on a circuit being open or closed, one end always has to have the circuit
closed to detect if the other end has opened or closed the circuit.
Management Information Base (MIB)
Specifications containing definitions of management information so that networked systems can be remotely
monitored, configured and controlled.
Management Server
Includes a web-based provisioning client, provisioning server, and SNMP proxy server used to manage all
agents connected to the system. The Management Server provides Gateway provisioning, Monitoring, and
Numbering Plan.
Media Access Control (MAC) Address
A layer 2 address, 6 bytes long, associated with a particular network device; used to identify devices in a
network; also called hardware or physical address.
Mu (µ)-Law
The PCM (Pulse Code Modulation) voice coding and companding standard used in Japan and North America.
See also
A-Law .
Network
A group of computers, terminals, and other devices and the hardware and software that enable them to
exchange data and share resources over short or long distances. A network can consist of any combination
of local area networks (LAN) or wide area networks (WAN).
Off-hook
A line condition caused when a telephone handset is removed from its cradle.
On-hook
A line condition caused when a telephone handset is resting in its cradle.
Packet
Includes three principal elements: control information (such as destination, origin, length of packet), data to be
transmitted, and error detection. The structure of a packet depends on the protocol.