6. Glossary - NEC UNIVERGE SV9100 Manual

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1.6

6. Glossary

802.1p
An IEEE standard for providing QoS using three bits (defined in 802.1q) to allow switches to reorder
packets based on priority level.
802.1q
An IEEE standard for providing virtual LAN (VLAN) identification and QoS levels. Three bits are used
to allow eight priority levels, and 12 bits are used to identify up to 4,096 VLANs.
ADPCM
Adaptive differential pulse code modulation. Process by which analog voice samples are encoded
into high- quality digital signals.
Bit
Binary Digit. The smallest unit of data transmission (0 or 1)
Broadband
Descriptive term for evolving digital technology that provides consumers a single switch facility
offering integrated access to voice, high-speed data service, video demand services, and interactive
delivery services.
BW
Bandwidth.
CBR
Constant Bit rate. Constant bit rate. QoS class defined by the ATM Forum for ATM networks. CBR is
used for connections that depend on precise clocking to ensure undistorted delivery.
CELP
Code excited linear prediction compression. Compression algorithm used in low bit-rate voice
encoding. Used in ITU-T Recommendations G.728, G.729, G.723.1.
Circuit Switching
Circuit switching is a WAN switching method in which a dedicated Physical circuit through a carrier
network is established, maintained, and terminated for each communication session. Used
extensively in telephone company networks, operates much like a normal telephone call.
CIR Committed Information rate
Rate at which a Frame Relay network agrees to transfer information under normal conditions,
averaged over a minimum increment of time. CIR, measured in bits per second, is one of the key
negotiated tariff metrics.
CODEC
In Voice over IP, Voice over Frame Relay, and Voice over ATM, a DSP software algorithm used to
compress/decompress speech or audio signals.