Allied Telesis AT-VP504E FXS, Administration Manual

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Appendix D - Glossary Administration Manual (H.323 Version)
AT-VP504E FXO 97
Jitter
1.
A distortion caused by the variation of a signal from its
references which can cause data transmission errors,
particularly at high speeds.
2.
Variations in amplitude, time, frequency or phase.
Layer 2 Layer 2 refers to the Data Link Layer of the commonly-referenced
multilayered communication model, Open Systems Interconnection
(OSI). The Data Link Layer is concerned with moving data across the
physical links in the network.
The Data-Link Layer contains two sublayers that are described in the
IEEE-802 LAN standards:
Media Access Control (MAC)
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 neighboring nodes in the network, selecting routes and quality of
service, and recognizing and forwarding to the transport layer incoming
messages for local host domains.
A router is a layer 3 device, although some newer switch also perform
layer 3 functions. The Internet Protocol (Internet Protocol) address is a
layer 3 address.
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 phone is on hook, no current is flowing on the line. When
you take your phone 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, since loop start signalling is
based on a circuit being open or closed, one end always has to have
the circuit closed to be able to detect if the other end has opened or
closed the circuit. See Ground Start.
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.