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Overview Installation Troubleshooting Contact FAQ Specifications Glossary License
Configuration: Basic Gateway TCP/IP Wireless USB
port mirroring A feature that enables one port (source) on the SBG940 to be copied to another port (destination) to be studied. The destination mirrors the transmitted (from) or received (to) data on the source port to enable the person managing the network to monitor activity.
port triggering A mechanism that allows incoming communication with specified applications. Primarily used for gaming applications.
PPP
PPTP | |
| developed jointly by several vendors. |
private IP | An IP address assigned to a computer on the SBG940 LAN by the DHCP server on the SBG940 for a |
address | specified lease time. Private IP addresses are used by the SBG940 LAN only; they are invisible to |
| devices on the Internet. See also public IP address. |
protocol | A formal set of rules and conventions for exchanging data. Different computer types (for example PC, |
| UNIX, or mainframe) can communicate if they support common protocols. |
provisioning | The process of autodiscovery or manually configuring a cable modem on the CMTS. |
PSTN | The public switched telephone network is the traditional |
| network. See also POTS. |
public IP | The IP address assigned to the SBG940 by the cable provider. A public IP address is visible to |
address | devices on the Internet. See also private IP address. |
Q
QAM | Quadrature Amplitude Modulation uses amplitude and phase modulation to encode multiple bits of |
| data in one signaling element. QAM achieves faster data transfer than amplitude or phase modulation |
| alone, but the signal is more prone to errors caused by noise. QAM requires a transmission circuit with |
| a higher CNR than alternate modulation formats such as QPSK. Two types of QAM are: |
| • 16 QAM encodes four bits per symbol as one of 16 possible amplitude and phase combinations. |
| • 64 QAM encodes six bits per symbol as one of 64 possible amplitude and phase combinations. |
QPSK | Quadrature Phase Shift Key (QPSK) modulation sends two bits of information per symbol period with |
| one symbol 90 degrees out of phase with other symbols. The four constellation points represented by |
| the coordinates (0,0 - 0,1 - 1,0 - 1,1) represent the four possible combinations. |
QoS | Quality of service describes the priority, delay, throughput, and bandwidth of a connection. |
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