Glossary
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PoE
Power over Ethernet. A standard for combining power supply with transmission of data
over the Ethernet. The source unit "injects" power into the Ethernet cable and the power
is "picked up" at the connected device.
PPPoE
Point-to-Point Protocol over Ethernet. A network protocol for encapsulating Point-to-
Point Protocol (PPP) frames inside Ethernet frames. By using PPPoE, users can virtually
"dial" from one machine to another over an Ethernet network, establish a point to point
connection between them and then securely transport data packets over the connection.
R
RF
Radio Frequency. Electromagnetic wave frequencies between 3 kHz and 300 GHz
including the frequencies used for communications signals (radio, television, cell-phone
and satellite transmissions) or radar signals.
S
SIM
Subscriber Identity Module. The SIM provides secure storing of the key identifying a
mobile phone service subscriber but also subscription information, preferences and
storage of text messages.
SIP
Session Initiation Protocol. An application-layer control (signaling) protocol for creating,
modifying, and terminating sessions with one or more participants. Used e.g. for Internet
telephony.
SPI
Security Parameter Index. An identification tag added to the header while using IPsec for
tunneling the IP traffic.
SSL
Secure Sockets Layer. The standard technology for keeping an Internet connection secure
and safeguarding any sensitive data that is being sent between two systems.
T
TE
Terminal Equipment - the equipment connected locally to the terminal.
TLS
Transport Layer Security. An updated, more secure, version of SSL.
U
UDP
User Datagram Protocol. Part of the TCP/IP suite of protocols used for data transferring.
UDP is known as a "stateless" protocol, meaning it doesn’t acknowledge that the packets
being sent have been received. For this reason, the UDP protocol is typically used for
streaming media. While you might see skips in video or hear some fuzz in audio clips, UDP
transmission prevents the playback from stopping completely.
USB
Universal Serial Bus. A specification to establish communication between devices and a
host controller (usually personal computers). USB is intended to replace many varieties of
serial and parallel ports. USB can connect computer peripherals such as mice, keyboards,
digital cameras, printers, personal media players, flash drives, and external hard drives.
UTC
Coordinated Universal Time. The International Atomic Time (TAI) with leap seconds
added at irregular intervals to compensate for the Earth’s slowing rotation. Leap seconds
are used to allow UTC to closely track UT1, which is mean solar time at the Royal
Observatory, Greenwich.
