Zultys MX250, Руководство по оборудованию

Страница: 53 / 62

B.
49
Local Area Network (LAN). A group of computers and associated devices that share a common
communications line and the resources of a single processor or server within a limited geographic
area, such as an office building. 10BaseT Ethernet is the most commonly used form of LAN. A
hardware device called a hub serves as the common wiring point, enabling data to be sent from
one machine to another over the network. LANs are typically limited to distances of less than 500
meters and provide low-cost, high-bandwidth networking capabilities within a small
geographical area.
Media Access Control (MAC) Address. A hardware number that uniquely identifies a computer or
other device. Within an Ethernet configuration, the MAC address is a 6-octet address assigned to
the network interface card. When your computer is connected to the Internet, a correspondence
table relates your IP address to your computer's physical (MAC) address on the LAN. The MAC
address is used by the Media Access Control sublayer of the Datalink Control (DLC) protocol
layer. Each physical device type has a different MAC sublayer.
Network Interface Card (NIC). A circuit board or card that is installed in a computer for the
purpose of connecting the computer to a network. Personal computers on a LAN usually contain
a NIC designed for a specific LAN transmission technology, such as Ethernet.
Network Time Protocol (NTP). A protocol that synchronizes computer clocks on an IP network.
Described by RFC 1305.
Per-Hop Behavior. The differential treatment an individual packet receives while being routed
through a network, as implemented by queue service or queue management disciplines. These
per-hop behaviors are useful and required in network nodes to deliver differentiated treatment
of packets regardless of end-to-end construction or intra-domain services. Per-Hop behavior is
discussed in RFC 2474 and Per-Hop Identification codes are defined in RFC 3140.
Point-to-Point Protocol (PPP). A protocol that defines a communication method between two
computers using a serial interface. Typically used to connect a personal computer to a server
through a phone line.
Proxy Server. A server that acts as an intermediary between a workstation and the Internet to
provide a caching service and ensure security and administrative control for the enterprise. The
proxy server is invisible to the workstation; all Internet requests and returned responses
involving the workstation appear to be directly with the addressed Internet server.
Public Switched Telephone Network (PSTN). The world-wide collection of voice-oriented public
telephone networks. Also referred to as Plain Old Telephone Service (POTS).
Quality of Service (QoS). The concept that transmission rates, error rate, and other characteristics
over a network or the Internet can be quantified, improved, and guaranteed (to a certain extent)
in advance. QoS is particularly concerned with the continuous transmission of high-bandwidth
video and multimedia data.
Real-Time Transport Control Protocol (RTCP). The protocol companion to RTP that provides
error, session control, and identification data about a transport session. Described by RFC 1889.
Real-Time Transport Protocol (RTP). An Internet protocol standard that specifies a method for
programs to manage the real-time transmission of multimedia data over unicast or multicast
network services. RTP combines its data transport with an control protocol (RTCP), which makes
it possible to monitor data delivery for large multicast networks. The ZIP 4x4 phone supports RTP
as a media channel for voice and video applications as described in RFC 1889.