Network+ - Module 12 - Voice And Video Over Ip

Front 1

AF (Assured Forwarding)

Back 1

In the DiffServ QoS technique, a forwarding specification that allows routers to assign data streams one of several prioritization levels. AF is specified in the DiffServ field in an IPv4 datagram.

Front 2

ATA (analog telephone adapter)

Back 2

An internal or externally attached adapter that converts analog telephone signals into packet-switched voice signals and vice versa.

Front 3

DiffServ (Differentiated Service)

Back 3

A technique for ensuring QoS by prioritizing traffic. DiffServ places information in the DiffServ field in an IPv4 datagram. In IPv6 datagrams, DiffServ uses a similar field known as the Traffic Class field. This information indicates to the network routers how the data stream should be forwarded.

Front 4

EF (Expedited Forwarding)

Back 4

In the DiffServ QoS technique, a forwarding specification that assigns each data stream a minimum departure rate from a given node. This technique circumvents delays that slow normal data from reaching its destination on time and in sequence. EF information is inserted in the DiffServ field of an IPv4 datagram.

Front 5

endpoint

Back 5

In SIP terminology, any client, server, or gateway communicating on the network.

Front 6

H.225

Back 6

A Session layer call signaling protocol defined as part of ITU’s H.323 multiservice network architecture. H.225 is responsible for call or videoconference setup between nodes on a VoIP or video-over-IP network, indicating node status, and requesting additional bandwidth and call termination.

Front 7

H.245

Back 7

A Session layer control protocol defined as part of ITU’s H.323 multiservice network architecture. H.245 is responsible for controlling a session between two nodes. For example, it ensures that the two nodes are communicating in the same format.

Front 8

H.323

Back 8

An ITU standard that describes an architecture and a suite of protocols for establishing and managing multimedia services sessions on a packet-switched network.

Front 9

H.323 gatekeeper

Back 9

The nerve center for networks that adhere to H.323. Gatekeepers authorize and authenticate terminals and gateways, manage bandwidth, and oversee call routing, accounting, and billing. Gatekeepers are optional on H.323 networks.

Front 10

H.323 gateway

Back 10

On a network following the H.323 standard, a gateway that provides translation between network devices running H.323 signaling protocols and devices running other types of signaling protocols (for example, SS7 on the PSTN).

Front 11

H.323 terminal

Back 11

On a network following the H.323 standard, any node that provides audio, visual, or data information to another node.

Front 12

H.323 zone

Back 12

A collection of H.323 terminals, gateways, and MCUs that are managed by a single H.323 gatekeeper.

Front 13

hosted PBX

Back 13

A digital PBX service provided over the Internet.

Front 14

Internet telephony

Back 14

The provision of telephone service over the Internet.

Front 15

IP-PBX

Back 15

A private switch that accepts and interprets both analog and digital voice signals (although some IP-PBXs do not accept analog lines). It can connect with both traditional PSTN lines and data networks. An IP-PBX transmits and receives IP-based voice signals to and from other network connectivity devices, such as a router or gateway.

Front 16

IP telephone

Back 16

A telephone used for VoIP on a TCP/IP-based network. IP telephones are designed to transmit and receive only digital signals.

Front 17

IPTV (IP television)

Back 17

A service in which television signals from broadcast or cable networks travel over packet-switched networks.

Front 18

MCU (multipoint control unit)

Back 18

A computer that provides support for multiple H.323 terminals (for example, several workstations participating in a videoconference) and manages communication between them. An MCU is also known as a video bridge.

Front 19

media gateway

Back 19

A gateway capable of accepting connections from multiple devices (for example, IP telephones, traditional telephones, IP fax machines, traditional fax machines, and so on) and translating analog signals into packetized, digital signals, and vice versa.

Front 20

MEGACO

Back 20

A protocol used between media gateway controllers and media gateways. MEGACO is poised to replace MGCP on modern converged networks, as it supports a broader range of network technologies, including ATM. Also known as H.248.

Front 21

MGC (media gateway controller)

Back 21

A computer that manages multiple media gateways and facilitates the exchange of call control information between these gateways.

Front 22

MGCP (Media Gateway Control Protocol)

Back 22

A protocol used for communication between media gateway controllers and media gateways. MGCP is currently the most popular media gateway control protocol used on converged networks.

Front 23

PBX (private branch exchange)

Back 23

A telephone switch used to connect and manage an organization’s voice calls.

Front 24

proxy server

Back 24

On a SIP network, a server that accepts requests for location information from user agents, then queries the nearest registrar server on behalf of those user agents. If the recipient user agent is in the SIP proxy server’s domain, then that server will also act as a go-between for calls established and terminated between the requesting user agent and the recipient user agent.

Front 25

redirect server

Back 25

On a SIP network, a server that accepts and responds to requests from user agents and SIP proxy servers for location information on recipients that belong to external domains.

Front 26

registrar server

Back 26

On a SIP network, a server that maintains a database containing information about the locations (network addresses) of each user agent in its domain. When a user agent joins a SIP network, it transmits its location information to the SIP registrar server.

Front 27

RSVP (Resource Reservation Protocol)

Back 27

As specified in RFC 2205, a QoS technique that attempts to reserve a specific amount of network resources for a transmission before the transmission occurs.

Front 28

RTCP (Real-time Transport Control Protocol)

Back 28

A companion protocol to RTP, RTCP provides feedback on the quality of a call or videoconference to its participants.

Front 29

RTP (Real-time Transport Protocol)

Back 29

An Application layer protocol used with voice and video transmission. RTP operates on top of UDP and provides information about packet sequence to help receiving nodes detect delay and packet loss. It also assigns packets a time stamp that corresponds to when the data in the packet were sampled from the voice or video stream. This time stamp helps the receiving node synchronize incoming data.

Front 30

set-top box

Back 30

In the context of IPTV, a device that decodes digital video signals and issues them to the television. Set-top boxes also communicate with content servers to manage video delivery.

Front 31

signaling

Back 31

The exchange of information between the components of a network or system for the purposes of establishing, monitoring, or releasing connections as well as controlling system operations.

Front 32

SIP (Session Initiation Protocol)

Back 32

An Application layer signaling and control protocol for multiservice, packet-based networks. With few exceptions, SIP performs much the same functions as the H.323 signaling protocols perform.

Front 33

softphone

Back 33

A computer configured to act like an IP telephone. Softphones present the caller with a graphical representation of a telephone dial pad and can connect to a network via any wired or wireless method.

Front 34

SS7 (Signaling System 7)

Back 34

A set of standards established by the ITU for handling call signaling on the PSTN (Public Switched Telephone Network).

Front 35

streaming video

Back 35

A service in which video signals are compressed and delivered over the Internet in a continuous stream so that a user can watch and listen even before all the data have been transmitted.

Front 36

toll bypass

Back 36

A cost-savings benefit that results from organizations completing long-distance telephone calls over their packet-switched networks, thus bypassing tolls charged by common carriers on comparable PSTN calls.

Front 37

unified messaging

Back 37

The centralized management of multiple types of network-based communications, such as voice, video, fax, and messaging services.

Front 38

user agent

Back 38

In SIP terminology, a user agent client or user agent server.

Front 39

user agent client

Back 39

In SIP terminology, end-user devices such as workstations, tablet computers, smartphones, or IP telephones. A user agent client initiates a SIP connection.

Front 40

user agent server

Back 40

In SIP terminology, a server that responds to user agent clients’ requests for session initiation and termination.

Front 41

video-on-demand

Back 41

A service in which a video stored as an encoded file is delivered to a viewer upon his request.

Front 42

video over IP

Back 42

Any type of video service, including IPTV, videoconferencing, and streaming video, that delivers video signals over packet-switched networks using the TCP/IP protocol suite.

Front 43

video phone

Back 43

A type of phone that includes a screen and can decode compressed video and interpret transport and signaling protocols necessary for conducting videoconference sessions.

Front 44

videoconferencing

Back 44

The real-time reception and transmission of images and audio among two or more locations.

Front 45

VoIP (Voice over IP)

Back 45

The provision of telephone service over a packet-switched network running the TCP/IP protocol suite.

Front 46

Webcast

Back 46

A streaming video, either on demand or live, that is delivered via the Web.