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An encyclopedia entry for "Switched Port Analyzer" is presented. Switched Port Analyzer (SPAN) refers to a feature of managed switches which extends the monitoring capabilities of existing network analyzers into a switched Ethernet environment. If attached to a SPAN port, a network analyzer can monitor traffic from other switched ports.

A definition of the term "Loop Transmission Facilities" is presented. It refers to telephony equipment that connects switching systems to customer premises equipment throughout the serving area.

A reference entry for "logical channel" is presented. It refers to a non-dedicated, packet-switched communications path between two or more network nodes. Packet switching enables many logical channels to exist simultaneously on a single physical channel.

A definition of the term "Label Imposition" is presented. It refers to the act of putting the first label or tag on a packet, which is a necessary procedure in a Multiprotocol label switching (MPLS) network for tunnel establishment.

An encyclopedia entry on "Interoffice Channel" is presented. In Local Exchange Carrier (LEC) tariffs, it refers to the channel connecting two serving wire centers located in two central offices. It can also mean the channel connecting two serving IXC Point of Presence (POPs)--interoffice transmission facilities used to connect LEC switching systems--in Interexchange Carrier tariffs.

An encyclopedia entry for "indication of camp-on" is presented. It refers to an audible tone generated by the telephone system. Attendant camp-on service enables an electronic switching system centrex attendant to hold incoming calls to busy lines. As the attendant reconnects and releases from the loop in response to timed reminders from the console, the customer may get the tone several times.

An encyclopedia entry for "GloBanD" is presented. It is a European Switched Nx64 data service consisting of one circuit whose bandwidth is a multiple of 64 kilobytes per second (kbps). However GloBanD, which follows the Comité Consultatif International Téléphonique et Télégraphique (CCITT) Q.931 recommendation, is available over T1 Primary Rate Interface (PRI) lines only. It is an overlay network, unlike MultiRate which is an integral part of the worldwide switched digital infrastructure.

A definition of the term "fixed wireless access," also known as wireless local loop, is presented. In the context of wireless communication system, it refers to a system in which office or home users are able to use the system through a direct connection with the switching center of the telecommunications carrier or the inter-exchange channel.

A definition of the term "datakit" is presented. It refers to a proprietary packet switching system similar to X.25 widely deployed by the Regional Bell Operating Cos. (RBOC). It supports host-to-host connections and EIA-232 connections for terminals, printers and hosts.

A definition of the term "Centrex" is presented. It is a central office exchange service, a type of Private Branch Exchange (PBX) service in which switching occurs at a local telephone station instead of at the company premises. With this service, there is no onsite switching at the customer premise and all customer connections go back to the Centrial Office of the service provider.

A definition of the term "adaptive design engineering" is presented. It refers to the process of providing specialized design and development of switching, transmission and customer-premises equipment or modifications of standard products to meet the specific needs of a customer.

An encyclopedia entry for "Link-by-Link Signaling" is presented. It is a signaling scheme wherein signaling messages are transmitted one link at a time in a multi-link connection. Link-by-Link Signaling, in the Signaling System 7 (SS7) system, is the procedure used to exchange signaling messages between two Signaling Points (SPs) that are either directly connected to each other, or are connected through Signaling Transfer Point (STPs).

An encyclopedia entry for "Yersinia" is presented. In computer security, this refers to a tool for performing layer 2 attacks. It allows an attacker to foil switches by injecting spurious Spanning Tree Protocol, Dynamic Host Configuration Protocol (DHCP), virtual local area network hopping (VLAN) Trunking protocol and other messages into a network. It is used to test the robustness of layer 2 protocols configuration.

An encyclopedia entry for "X Recommendations" is presented. It refers to a set of CCITT, currently known as the Telecommunication Standardization Sector of the International Telecommunications Union (ITU-T) documents that describe data communication network standards. Examples of data communication network standards include the X.25 Packet Switching standard, X.400 Message Handling System and X.500 Directory Services.

A definition of the term "workgroup switching" is presented. It refers to the method of switching that provides high-speed translational bridging between Ethernet and Copper Distributed Data Interface (CDDI) or Fiber Distributed Data Interface (FDDI), and high-speed transparent bridging between Ethernet networks.

A reference entry for "Wireless Private Automatic Branch Exchange" (WPABX) is presented. The WPABX refers to a customer premise telephone switching system using wireless technology to link the individual user stations to the central switching unit. It is capable of interfacing to a telephone central office with trunk groups and routing calls based on a 3- or 4-digit telephone extension number.

A reference entry for "Wire Center" is presented. A Wire Center is a building as used in the context of telecommunication. This is where one or more local switching systems are installed and where the outside cable plant is connected to the central office equipment.

A definition of the term "Wink Start Signaling" is presented. In the context of telecommunication, this is the most commonly used trunk signaling type. The originating trunk circuit goes off-hook in Wink Start operation. The off-hook signal is detected by a remote switch, which then transmits an off-hook pulse and then returns to the on-hook state.

A definition of the term "Virtual Tributary" (VT) is presented. It refers to a signal designed for transport and switching for sub-STS-1 payloads.

An encyclopedia entry for "Virtual Switching" is presented. It refers to a technology that allows multiple switching functions to occur in one physical device. The virtual switching technology enables a single switch to be used in different applications, each of which may have its own discrete performance and security controls. Based on the entry, the use of the technology will allows service providers to create a dynamic service mix.

A definition of the term "virtual private LAN service (VPLS)" is presented. It refers to a multi protocol label switching (MPLS) application defined by the Internet Engineering Task Force (IETF). It is stated that VPLS allows geographically dispersed sites to share an Ethernet broadcast domain by connecting each site to an MPLS-based network.

A reference entry for "Very Compact Digital eXchange" is presented. In telecommunications, this refers to the smallest configuration of the Lucent 5ESS family. Using the same hardware and software as the full-size 5ESS switch, this compact, packet-ready switch delivers a range of services from a single platform.

A definition of the term "User Adaptation Layers (UA)" is presented. It refers to a collection of the Signaling User Adaptation Layers in the SIGTRAN telecommunication protocol suite. The protocol suite includes, SS7 TCAP-User Adaptation Layer, SS7 SCCP-User Adaptation Layer, and SS7 ISUP-User Adaptation Layer.

A definition of the term "Unbundled Network Elements Loop" (UNE-L) is presented. It is an alternative to UNE Platform. It allows competitive local exchange carriers access to or operate their own local switch. The network loop that runs to customer's house is then leased by the carriers, and cross-connected to the carriers' switch.

A definition of the term "UMTS Mobile Switching Center" is presented. It is a type of Mobile Switching Center that provides Universal Mobile Telecommunication System (UMTS) 3G wireless telephony switching services and controls calls between telephone and data systems.

A definition of the term "Trunk" is presented. It refers to the physical and logical connections between two switches through which network traffic travels.

A definition of the term "Traffic Service Position System" in telecommunications is presented. The term refers to the ability of the former AT&T 5ESS Operator Services Position System (OSPS) to provide several applications simultaneously on one switching system. One OSPS switch can serve up to 128 teams of operators handling different applications, such as directory, tool and operator assistance.

An encyclopedia entry for "Token Ring Inter-Switch Link" (TRISL) is presented. It is a Cisco protocol for interconnecting multiple routers and switches and maintaining Virtual Local Area Network (VLAN) information as traffic goes between routers and switches. It also offers a way to transport native Token Ring frames from multiple VLAN across a 100-megabyte (MB) Fast Ethernet link.

A definition of the term "Time Slot Interchange" (TSI) is presented. It pertains to the device in a switching system that permits any perceived incoming byte from an input tributary to be mapped to any outgoing or transmitting byte, respectively, on the associated output tributary.

A definition of the term "Time Division Switching" is presented. It refers to a switching of time-division multiplexed (TDM) channels by shifting bits between time slots in a TDM frame.

A definition of the term "Termid" is presented. It is also referred to as XID. It is a systems network architecture (SNA) cluster controller identification for switched lines only.

A definition of the term "Tandem Trunk" is presented. It refers to a trunk circuit which connects a tandem switch to another tandem switch or to a telephone company central office.

A definition of the term "Tandem Tie Trunk Switching" is presented. It refers to a switched network configuration in which transmission can be routed through consecutive tie trunks.

A definition of the term "Tandem Switching" is presented. It refers to the switching of long distance calls in PSTN. It is a telephony term which means to connect in series. A tandem switch is an intermediate switch or connection between an originating telephone call and the final destination of the call.

A definition of the term "T3" is presented. It refers to a digital WAN carrier facility. It transmits DS-3-formatted data at 44.736 Mbps through the telephone switching network.

A definition of the term "T1 access line" is presented. It refers to a 1.544 Mbps T1 line that provides 24 64 Kbps data channels and uses in-band signaling. This type of line can contain all switched channels, all nailed-up channels, or a combination of switched and nailed-up channels.

A definition of the term "T1" is presented. It refers to a digital WAN carrier facility. T1 transmits DS-1-formatted data at 1.544 Mbps through the telephone-switching network, using AMI or B8ZS coding.

A definition of the term "Switch-to-Switch Protocol" is presented. Switch-to-Switch Protocol (SSP) allows routers to establish Data-Link Switching (DLSw) connections, locate resources, forward data and handle flow control and error recovery.

An encyclopedia entry for "Switching Module" is presented. Switching Module (SM) refers to a component of the 5ESS switch developed by Lucent Technologies. SM terminates subscriber loops (lines) and inter-exchange trunks interfacing the 5ESS switch.

An encyclopedia entry for "Switching Matrices" is presented. Switching Matrices refer to the ratio of the number of input terminals to the number of output terminals of a switch. They also describe the mechanism that provides signal paths between its input and output terminations. Modern space-division switches are electronically implemented using integrated circuits.

A definition of the term "Switching Fee" is presented. It refers to the per-line fee imposed by the Local Exchange Carrier (LEC) to reprogram a switching system to change customer's default long distance carrier.

An encyclopedia entry for "Switching" is presented. Switching refers to the process that establishes connections of different network segments. The two main categories of switching are packet switching and circuit switching. Packet switching transmits data packets individually to its destination, while circuit switching establishes connections on demand.

An encyclopedia entry for "Switchhook Flash" is presented. Switchhook Flash is a signaling technique in which the signal originates by momentarily depressing the switchhook. Such technique is said to be sensitive to variations in the time of depression.

A definition of the term "Switchhook" is presented. It refers to a switch on a telephone set that is associated with the structure supporting the receiver or handset.

An encyclopedia entry for "Switched-56" is presented. Switched-56 is a data service that is consists of a single 56 kilobytes per second (kbps) channel. It is the only data service that is available to T1 access lines and Switched-56 lines. Since Switched-56 was the first available data service, the service and the lines accessing it were called Switched-56.

An encyclopedia entry for "Switched-1536" is presented. Switched-1536 refers to a data service that is consists of a single 1536 kilobytes per second (kbps) circuit. It also known as H11 data service and is composed of 24 channels on the line. The Switched-1536 service is only available over T1 Primary Rate Interface (PRI) lines.

An encyclopedia entry for "Switched-384" is presented. Switched-384 is a data service that is consists of a single 384 kilobytes per second (kbps) circuit called H0 channel. It is also known as H0 data service and is only available over T1 Primary Rate Interface (PRI) lines.

A definition of the term "Switched Virtual Circuit" is presented. Switched Virtual Circuit (SVC) is a type of virtual circuit (VC) set up dynamically when needed.

An encyclopedia entry for "Switched LAN" is presented. Switched LAN refers to a Local Area Network (LAN) where all nodes are connected using a LAN switch rather than a Hub or bridge.

An encyclopedia entry for "Switched Digital Service" is presented. Switched Digital Service (SDS) refers to a data application service that provides a digital access line through digital central offices. Such service allows customers to simultaneously transmit two-way digital signals at a speed of 56 Kilobytes per second (Kbps) on a dial-up basis.