Multi-Tech Systems MVP120 - Manual (Page 94)

Foreign Exchange Station (FXS): See FX, FXO. To generate a call from the computer telephony system to the POTS set, a FXS
connection must be configured.
Forward Explicit Congestion Notification (FECN): A bit that tells you that a certain frame on a particular logical connection has
encountered heavy traffic. The bit provides notification that congestion-avoidance procedures should be initiated in the same
direction of the received frame. See also BECN (Backward Explicit Congestion Notification).
Frame: A group of data bits in a specific format to help network equipment recognize what the bits mean and how to process them.
The bits are sent serially, with a flag at each end signifying the start and end of the frame.
Frame Relay: A form of packet switching that uses small packets and that requires less error checking than other forms of packet
switching. Frame relay is effective for sending "bursty" data at high speeds (56/64K, 256K, and 1024K bps) over wide area
networks. Frame Relay specifications are defined by ANSI documents ANSI T1.602, T1.606, T1S1/90-175, T1S1/90-213, and
T1S1/90-214. In using frame relay, blocks of information (frames) are passed across a digital network interface using a "connection
number" that is applied to each frame to distinguish between individual frames.
Frame Relay Forum: A non-profit organization of 300+ vendors and service providers, based in Foster City, CA, that are develop-
ing and deploying frame relay equipment.
Frame Relay Implementors Forum: A group of companies supporting a common specification for frame relay connection to link
customer premises equipment to telco network equipment. Their specification supports ANSI frame relay specs and defines
extensions such as local management.
Frame Relay Access Device (FRAD): A piece of equipment that acts as a concentrator or frame assembler/dissassembler that
can support multiple protocols and provide basic "routing" functions.
G
Gatekeeper: An H.323 entity that provides address translation, control access, and sometimes bandwidth management to the LAN
for H.323 endpoints.
Gateway: 1. A functional unit that interconnects two computer networks with different network architectures. A gateway connects
networks or systems of different architectures. A bridge interconnects networks or systems with the same or similar architectures. 2.
A network that connects hosts. 3. An H.323 entity that provides real-time, two-way communications between H.323 terminals on the
LAN and other ITU terminals on a WAN, or to another H.323 Gateway.
Graphical User Interface (GUI): A type of computer interface consisting of a visual metaphor of a real-world scene, often of a
desktop. Within that scene are icons, representing actual objects, that the user can access and manipulate with a pointing device.
H
H.323: An umbrella recommendation from the International Telecommunications Union (ITU) that sets standards for multimedia
communications over Local Area Networks (LANs) that do not provide a guaranteed Quality of Service (QoS).
H.323 Endpoint: The clients in an H.323 network. They are typically video conferencing, audio conferencing, or other multimedia
systems implemented by end users to communicate in real time. The H.323 standard requires that every endpoint support the
G.711 ITU standard for speech compression, H.245 protocol for controlling media between H.323 endpoints, Q.931 signal protocol
for establishing and terminating calls, RAS (Registration/Admissions/Status) channel data stream used to communicate with a
gatekeeper (optional), and RTP/RTCP (Real-Time Protocol/Real-Time Control Protocol) for carrying packetized real-time media on
IP networks.
H.323 Entity: Any H.323 component, including terminals, Gateways, Gatekeepers, Multipoint Controllers (MCs), Multipoint
Processors (MPs), and Multipoint Control Units (MCUs).
Handshaking: A process that two modems go through at the time of call setup to establish synchronization over the data
communications link. It is a synchronization and negotiation process accomplished by the exchange of predefined, mutually
recognized control codes.
High-level Data Link Control (HDLC): An ISO standard, bit-oriented data communications protocol that provides nearly error-free
data transfers.
I
Hexadecimal: A base 16 numbering system used to represent binary values. Hex uses the numbers 0-9 and the letters A-F:
usually notated by an "h" (e.g., "4CF h", read "four charley fox, hex"). The result is that one hex digit represents a 4-bit value.
Implicit congestion management: A method of informing the terminal that the network is busy. This method relies on the end-
system protocol to detect and fix the congestion problem. (TCP/IP is an example of a protocol using only implicit congestion
management.) See also "explicit congestion management".
In-band: Refers to the type of signalling over the conversion path on an ISDN call. Contrast "out-of-band".
Insufficient Ones: A T1 error condition that is logged when less than one 1 in 16 0s or less than 12.5 % average 1s density is
received.