Glossary of Terms
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IEEE networking standard for a variant of Gigabit Ethernet which runs on multimode and single mode fiber optic cable at a 1330 nm wavelength.
IEEE networking standard for a variant of Gigabit Ethernet which runs on multimode fiber optic cable at an 850 nm wavelength.
IEEE networking standard for a variant of Gigabit Ethernet which runs on unshielded twisted pair cable.
IEEE networking standard for Ethernet which runs on multimode fiber optic cabling at 100 Mbps. This is one version of Fast Ethernet.
IEEE networking standard for 100 Mbps twisted-pair Ethernet cabling; also called Fast Ethernet.
IEEE networking standard for 10 Mbps twisted-pair Ethernet cabling.
Automatic Number Identification; A telephone function that transmits the billing number of the incoming call (Caller ID, for example).
Application Service Provider - An independent, third-party provider of software-based services delivered to customers across a wide area network (WAN).
Answer-Siezure Rate - The ratio of successfully connected calls to attempted calls (also called 'Call Completion Rate'). ASRs vary by routes. A typical ASR to Pakistan is lower than that of Germany. Reasons for this include the quality of the network and the fact that it's less likely that a call to Pakistan will encounter a device such as an answering machine.
- Access Control Lists
Database that describes the type of access each user has to a service.
A set of characters that identifies an individual network node.
Border Gateway Protocol, an Internet protocol that enables groups of routers (called autonomous systems) to share routing information so that efficient, loop-free routes can be established. BGP is commonly used within and between Internet Service Providers (ISPs). The protocol is defined in RFC 1771.
An extension of the Border Gateway Protocol, an Internet protocol that enables groups of routers (called autonomous systems) to share routing information so that efficient, loop-free routes can be established. BGP is commonly used within and between Internet Service Providers (ISPs).
Interconnection in a LAN or WAN between subnetworks or workgroups. The high-speed connection to lower-speed subnets. For example, a Gigabit Ethernet backbone connected to Fast Ethernet subnets.
The maximum amount of data that can be transmitted in a fixed amount of time; usually expressed in bits-per-second or bytes-per-second.
- Bell Operating Companies (BOC)
The family of corporations created during the divestiture of AT&T. BOCs are independent companies which service a specific region of the US. Also called Regional Bell Operating Companies (RBOCs) and Incumbent Local Exchange Carrier (ILEC).
Competitive Local Exchange Carrier. An alternative to the existing local phone company.
- Carrier ENUM
- Carrier Hotel
- Category 5 (CAT5)
Networking standard certifying that a copper wire cable can carry data at up to 100 Mbps. See also UTP.
- Circuit-switched Network
A technology used by the PSTN that allocates a pair of conductors for the exclusive use of one communication path. Circuit switching allows multiple conversations on one talk path only if the end-users multiplex the signals prior to transmission.
Placing equipment owned by a customer in another company's secured facility. Co-location facilities offer the space for equipment, security, and other services, as well as interconnections and Internet access for installed equipment.
Voice encoding/decoding mechanism. Codecs are used to compress the voice signal into data packets. Each codec has different bandwidth requirements. The most popular codecs are: G.729, G.729A, G.723.1, G711A, and G.711mU.
Direct Inward Dialing; The ability to make a telephone call directly into an internal extension without having to go through the operator.
Direct Outward Dialing; The ability to dial out directly without having to go through the operator.
- Data-link Layer
See Layer 2.
The international public telecommunication numbering plan.
Electronic Number Mapping (ENUM) is an IETF Standard (RFC 3761, was RFC 2916). It defines a DNS-based architecture and protocol by which an E.164 number can be expressed as a Fully Qualified Domain Name (FQDN). The result of an ENUM query is a series of DNS NAPTR records which can be used to contact a resource (e.g. URI) associated with a telephone number.
- Ethernet Fabric
Fully Qualified Domain Name - A host specification including the entire domain structure complete to the top-level domain (.com, .edu, .mil, and so on). For example, "www" is a hostname and "www.thevpf.com" is an FQDN.
- Fast Ethernet
An IEEE networking standard for transmitting data at 100 Mbps. See 100BASE-TX also.
The ability of a device to prevent or recover from network and internal failures. Key elements of fault tolerance include hot-swappable modules, redundant load-sharing power supplies, passive backplanes, and redundant cooling systems.
- Full Duplex
The process of operating a circuit so that each end can transmit and receive simultaneously.
This is a hardware or software set-up that functions as a translator between two dissimilar protocols. A gateway can also be the term to describe any mechanism providing access to another system.
Gigabits per second.
- Gigabit Ethernet
Networking standard for transmitting data at 1000 Mbps.
Packet based multimedia communication systems
- Half Duplex
A channel or device which can communicate in both directions, but not simultaneously.
Any entity on the network that can initiate a transmission. A router, a server or a workstation.
Inter-Asterisk eXchange (IAX) protocol is used by Asterisk VoIP PBX as an alternative to SIP or H323 when connecting to other devices that support IAX. IAX is a binary based protocol and claims to provide greater efficiency then RTP and any Codec.
Internet Engineering Task Force
A Layer 3 (network layer) protocol that contains addressing information and control information that allow packets to be routed.
Internet Service Provider
Internet Telephony Service Provider
Interactive Voice Response is a software application that accepts a combination of voice telephone input and touch-tone keypad selection and provides appropriate responses in the form of voice, fax, callback, e-mail and perhaps other media. IVR is usually part of a larger application that includes database access. Common IVR applications include: bank and stock account balances and transfers, surveys and polls, caller authorization centers (for example, the MCCP), etc.
Inter-exchange Carrier: Post-1984 name for a long-distance phone company in the United States.
The Internet is made up of more than 65 million computers in more than 100 countries covering commercial, academic and government endeavors.
- Internet Telephony
Jitter is the variance of latency (i.e. delay) in a connection.
Local Area Network. A network where computers are connected in close proximity, such as in the same building or office park; a system of LANs connected at a distance is called a wide-area network (WAN).
Local Access and Transport Area. LATA is a geographic territory used primarily by local telephone companies to determine charges for intrastate calls.
Least Cost Routing. This process means searching for the optimum traffic routes via one or several traffic routings enabling a cost reduction.
Local Exchange Carrier. The local telephone company serving an area.
The delay or time span between the voice being digitalized at the senders Location and then output at the receivers end is the latency of a connection. Latency is influenced by the distance the data has to travel, the packet size, the number and delay time of network elements between the terminals and of course the latency generated by the terminals themselves when sending, receiving, encoding, decoding and compensating jitter.
- Layer 1
The first, or physical, layer of the open systems interconnection (OSI) model. Delivers data across a network link. This layer must regulate signaling and keep the signal strong. Hubs, repeaters and concentrators operate at Layer 1. All packets received are repeated on the wire.
- Layer 2
The second, or data-link layer, of the open systems interconnection (OSI) model. The media access control (MAC) layer. Transmits packets across a Layer 1 physical link by reading the hardware or MAC source and destination addresses in each packet. Switching operates at Layer 2. Switches have a forwarding table of the hardware addresses of the devices connected to them. When packets arrive, the switch reads the Layer 2 address and if it matches one in the table, forwards it to that port. Otherwise, it forwards or .floods. the packet to all ports.
- Layer 3
The third, or routing, layer of the open systems interconnection (OSI) model. The network layer routes data to different LANs and WANs based on network address.
- Layer 4
The fourth, or transport, layer of the open systems interconnection (OSI) model. It encompasses network services that provide end-to-end management of a communications session.
- Layer 7
The seventh, or application, layer of the open systems interconnection (OSI) model. It defines the services that directly support applications such as software for network management, electronic mail or file transfers.
Media Access Control. Layer 2 of the open systems interconnection OSI model. The data-link layer responsible for scheduling, transmitting and receiving data on a local area network.
- MAC Address
Media Access Control address. The unique physical address of each device's network interface card.
Metropolitan Area Network, a data network designed for a town or city. In terms of geographic breadth, MANs are larger than local area networks (LANs), but smaller than wide area networks (WANs). MANs are usually characterized by very high-speed connections using fiber optical cable or other digital media.
Media Gateway Control Protocol. A voice protocol that runs in conjunction with SS7 and an IP protocol such as H.323 or SIP to bridge circuit switched and packet networks. MGCP separates the signalling and call control from the media gateway.
Megabits per second.
- Meshed Topology
A network built with a mixture of different network topologies. For example a high bandwidth backbone network that connects to a collection of slower segments.
- Multimode Fiber Cable
Fiber cable with a wide core. Light is reflected along the core at multiple angles, and is propagated along multiple paths, each path with a different length and hence a different time to traverse the fiber. These multiple angles or modes cause the signal elements to spread out in time, so that distortions occur that limit the distance over which the integrity of the light signal can be maintained. Multimode fiber is the predominant type of LAN fiber installed within buildings and is less expensive than single mode fiber.
Number Authority Pointer (as used within IETF RFC 2916/3761 to identify possible urls and numbers that can be returned).
Original called number. Original called number The OCN is the phone number of the original called party, regardless of use (call redirection...).
Point of presence. The point where a long distance carrier connects to a local phone company or to a user if a local company is not involved. For online services and Internet service providers, the POP is the local exchange users dial into via modem.
The Public Switched Telephone Network
Peer-to-peer is a communication model in which computing devices (desktops, servers, routers, and other smart devices) link directly to each other without an intermediary device (in the same communication level; e.g. Layer 3).
Peering is when two networks perform an interconnect to exchange traffic. This is the normal method of interconnection between networks which make up the global Internet. Also known as IP Peering
Quality of Service pertains to the quality of a connection and this is especially important for connections relaying voice since the user feels the impact immediately. A retransmission cannot make up for the lost data. The internet protocol was devised as a .best effort. data network and thus it does consider jitter, latency or even data loss a problem. Ergo, it does not handle voice well per se. To make the transmission of voice possible it must be given the necessary priority and bandwidth. There are mechanisms for reserving bandwidth (see RSVP) but they add network equipment with an additional burden of handling this functionality and slow down establishing connections. The other pragmatic approach to this problem is to acknowledge that normally the access point (interconnection between LAN and WAN) is the most critical section. By prioritising the packets (see ToS) (of course the network equipment has to Support this) and ensuring that the access point is not overloaded good QoS can be achieved. The data traffic load in the backbone is about 10 times that of voice (thanks to WWW) of carriers so this should not be the problem.
Request For Comments - the name for an Internet standards- related specification.
RTP (realtime transport protocol) labels all information transferred by a sender with a timestamp. By examining the timestamps the receiver is able to sort the packets in the original order and synchronize real time streams and/or compensate jitter in audio data.
Registry is a database containing information.
A network device that forwards packets to destinations based on Layer 3 IP addresses. A router implements various protocols to maintain information on the location of other routers. A router reads the Layer 3 network address information in every packet that it receives and determines whether it should be dropped or forwarded. If it is to be forwarded, the router looks in its routing table to find the best route between a sender and receiver.
The process of delivering a message across a network or networks.
Session Initiation Protocol (SIP) is a signaling protocol uses text based messages (like HTTP and SMTP) and supports multimedia communications like user location, capability, availability, call setup/handling.
Signaling System 7 is an international telecommunications protocol standard used to process calls on the public switched telephone network (PSTN)
- Session border controller (SBC)
A new category of network equipment that enables interactive communications across IP network borders. SBCs closely integrate signaling and media control and serve as a transit point for all signaling and media streams going through the service provider's network. The ability to traverse firewalls and network address translators ensures ubiquity of network reach, whilst advanced routing and interworking capabilities maintain mission-critical quality of service.
- Single Mode Fiber Cable
Fiber with a relatively narrow diameter, through which only one mode will propagate. Carries higher bandwidth than multimode fiber, but requires a light source with a narrow spectral width.
A softswitch is defined as media gateway controller software that provides call control and resource management for a media gateway. Call control relates to the setup and termination of calls, including call routing. A softswitch also provides call authentication and authorization, and accounting services by accessing information available in an existing Signaling System 7 (SS7) network. Also referred to as media gateway controller or call agent.
- Subnet Addressing
A method that a manager can use to span multiple physical networks using a single IP network address. Local routers and intelligent switches use extensions of the IP network address to identify and route traffic to local, physical segments.
- Subnet Mask
A number that a manager enters to tell the switch how to filter incoming packets. For example, a subnet mask of 255.255.0.0 for the address 126.96.36.199 tells the switch to only accept traffic destined for IP addresses that begin with 192.3. All other packets are dropped.
A network device that filters and forwards packets between LAN segments and or desktops.
Transmission Control Protocol/Internet Protocol. The suite of communications protocols used to connect hosts on the Internet.
The physical or logical layout, or configuration of a network.
Encapsulation data in an IP packet for transport across the internet.
Uniform Resource Identifier - a URL is a URI.
Uniform Resource Locator
- User ENUM
Virtual LAN. A logical, not physical, group of devices, defined by software. VLANs allow network administrators to resegment their networks without physically rearranging the devices or network connections.
A method of sending voice information over a packet-switched network, such as the Internet or the VPF, using TCP/IP.
Voice Peering Fabric.
- Virtual Private Network (VPN)
A private network that is configured within a public network. Also see Tunnelling.
Wide Area Network. A network that uses telecommunications technology to connect computers or networks over long distances.