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Videoconferencing
Glossary of Terms |
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List of acronyms
defined:
Source for definitions
- http://www.whatis.com
ABILENE:
Abilene is an Internet 2 high-speed advances backbone research network that
connects regional network aggregation points to support the work of over 180
Internet 2 universities in developing advanced Internet applications.
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ANJ: Access New
Jersey. An ATM network funded and operated by Verizon with a goal to
provide connectivity to every K-12 school in NJ. ANJ operates a video
portal using this statewide network.
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ARIN:
The American Registry of Internet Numbers (ARIN) is the organization in the U.S.
that manages IP
address numbers for the U.S. and assigned territories. Because Internet
addresses must be unique and because address space on the Internet is limited,
there is a need for some organization to control and allocate address number
blocks. IP number management was formerly a responsibility of the Internet
Assigned Numbers Authority (IANA),
which contracted with Network Solutions Inc. for the actual services. In
December 1997, IANA turned this responsibility over to ARIN, which, along with
Reseaux IP Europeens (RIPE) and Asia Pacific Network Information Center (APNIC),
now manages the world's Internet address assignment and allocation. Domain
name management is still the separate responsibility of Network Solutions
and a number of other registrars accredited by the Internet Corporation for
Assigned Names and Numbers (ICANN).
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AS:
Autonomous System. On the Internet, an autonomous system (AS) is the unit
of router
policy, either a single network or a group of network
that is controlled by a common network administrator (or group of
administrators) on behalf of a single administrative entity (such as a
university, a business enterprise, or a business division). An autonomous system
is also sometimes referred to as a routing domain.
An autonomous system is assigned a globally unique number, sometimes called an
Autonomous System Number (ASN).
Networks within an
autonomous system communicate routing information to each other using an
Interior Gateway Protocol (Interior
Gateway Protocol). An autonomous system shares routing information with
other autonomous systems using the Border Gateway Protocol (Border
Gateway Protocol). Previously, the Exterior Gateway Protocol (Exterior
Gateway Protocol) was used. The Internet's protocol guideline for
autonomous systems, after offering a definition similar to the one above,
provides a more technical definition as follows:
An AS is a connected
group of one or more Internet
Protocol prefixes run by one or more network operators which has a SINGLE
and CLEARLY DEFINED routing policy.
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ATM:
ATM (asynchronous transfer mode) is a dedicated-connection switching technology
that organizes digital data into 53-byte
cell
units and transmits them over a physical medium using digital signal technology.
Individually, a cell is processed asynchronously relative to other related cells
and is queued before being multiplexed over the transmission path.
Because ATM is
designed to be easily implemented by hardware (rather than software), faster
processing and switch
speeds are possible. The prespecified bit rates are either 155.520 Mbps
or 622.080 Mbps. Speeds on ATM networks can reach 10 Gbps.
Along with Synchronous Optical Network (SONET)
and several other technologies, ATM is a key component of broadband ISDN (BISDN).
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BGP4:
BGP (Border Gateway Protocol) is a protocol
for exchanging routing information between gateway
hosts
(each with its own router)
in a network of autonomous
systems. BGP is often the protocol used between gateway hosts on the
Internet. The routing table contains a list of known routers, the addresses they
can reach, and a cost metric
associated with the path to each router so that the best available route is
chosen.
Hosts using BGP
communicate using the Transmission Control Protocol (TCP)
and send updated router table information only when one host has detected a
change. Only the affected part of the routing table is sent. BGP-4, the latest
version, lets adminstrators configure cost metrics based on policy statements.
(BGP-4 is sometimes called BGP4, without the hyphen.)
BGP communicates with autonomous (local) networks
using Internal BGP (IBGP) since it doesn't work well with IGP. The routers
inside the autonomous network thus maintain two routing tables: one for the
interior gateway protocol and one for IBGP.
BGP-4 makes it easy to
use Classless Inter-Domain Routing (CIDR),
which is a way to have more addresses within the network than with the current IP
address assignment scheme.
BGP is a more recent
protocol than the Exterior Gateway Protocol (EGP).
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CODEC:
Coder Decoder for video signals.
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CTM:
Click To MeetTM. First Virtual Communications, Inc., product that combines a
directory service for H.320, H.321, and H.323 endpoints in a multimedia
environment.
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COMMUNITY OF INTEREST: A
grouping of Verizon customers with similar interests. NJEDge.Net will be a Community of Interest for Extra-net traffic.
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DNS:
The domain name system (DNS) is the way that Internet domain
names are located and translated into Internet
Protocol addresses. A domain name is a meaningful and easy-to-remember
"handle" for an Internet address.
Because maintaining a
central list of domain name/IP address correspondences would be impractical, the
lists of domain names and IP addresses are distributed throughout the Internet
in a hierarchy of authority. There is probably a DNS server within close
geographic proximity to your access provider that maps the domain names in your
Internet requests or forwards them to other servers in the Internet.
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DSL:
DSL (Digital Subscriber Line) is a technology for bringing high-bandwidth
information to homes and small businesses over ordinary copper telephone lines.
xDSL refers to different variations of DSL, such as ADSL, HDSL, and RADSL.
Assuming your home or small business is close enough to a telephone company central
office that offers DSL service, you may be able to receive data at rates up
to 6.1 megabits (millions of bits) per second (of a theoretical 8.448 megabits
per second), enabling continuous transmission of motion video, audio, and even
3-D effects. More typically, individual connections will provide from 1.544 Mbps
to 512 Kbps downstream and about 128 Kbps upstream. A DSL line can carry both
data and voice signals and the data part of the line is continuously connected.
DSL installations began in 1998 and will continue at a greatly increased pace
through the next decade in a number of communities in the U.S. and elsewhere.
Compaq, Intel, and Microsoft working with telephone companies have developed a
standard and easier-to-install form of ADSL called G.Lite
that is accelerating deployment. DSL is expected to replace ISDN
in many areas and to compete with the cable
modem in bringing multimedia and 3-D to homes and small businesses.
DS1
1.544 Megs
DS3 Fractional
10 Megs
DS3
20 Megs
DS3
45 Megs
OC3
155 Megs
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EXTRA-NET:
Communications traffic over the NJEDge.Net network that goes from one member to another via the private virtual circuits of
NJEDge.Net.
(Member-to-Member)
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GATEKEEPER:
The gatekeeper is the most powerful management
tool available for an H.323 multimedia network. As the brain of the H.323
network, this application performs essential control, administrative, and
managerial functions required to maintain the integrity of networks in both
enterprise and carrier environments.
This component of the network provides bandwidth
managements and quality of service for H.323
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GATEKEEPER ZONES:
A Zone is collection of terminals, gateways,
multimedia conference managers etc. managed by one H.323 Gatekeeper. Zones are
an important part of network topology.
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H.321:
The ITU standard for adaptation of H.320 videoconferencing over digital networks
such as B-ISDN.
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H.323:
The ITU standard for videoconferencing over packet switched networks such as
LANs and the Internet.
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IGP:
An IGP Interior Gateway Protocol) is a protocol for exchanging routing
information between gateway (hosts with routers) within an autonomous network
(for example, a system of corporate local area networks). The routing
information can then be used by the Internet Protocol or other network protocols
to specify how to route transmissions.
There are two commonly used IGPs: the Routing Information Protocol(RIP) and
the Open Shortest Path First (OSPF)protocol.
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INTERNET: The Internet
is a worldwide system of computer networks - a
network of networks in which users at any one computer can, if they have
permission, get information from any other computer (and sometimes talk
directly to users at other computers).
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INTERNET2:
Internet2 is a consortium being led by over 180 universities working in
partnership with industry and government to develop and deploy advanced network
applications and technologies, accelerating the creation of tomorrow's Internet.
Internet2 is recreating the partnership among academia, industry and government
that fostered today’s Internet in its infancy. The primary goals of Internet2
are to:
1. Create a leading edge network capability for the national research community
2. Enable revolutionary Internet applications
3. Ensure the rapid transfer of new network services and applications to the
broader Internet community.
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INTRANET:
The campus network and traffic, which stays within it.
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ISDN:
ISDN (Integrated Services Digital Network) is a set of CCITT/ITU standards for
digital transmission over ordinary telephone copper wire as well as over other
media. Home and business users who install an ISDN adapter
(in place of a modem)
can see highly-graphic Web pages arriving very quickly (up to 128 Kbps).
ISDN requires adapters at both ends of the transmission so your access provider
also needs an ISDN adapter.
There are two levels
of service: the Basic Rate Interface (BRI),
intended for the home and small enterprise, and the Primary Rate Interface (PRI),
for larger users. Both rates include a number of B-channels and a D-channels.
Each B-channel
carries data, voice, and other services. Each D-channel
carries control and signaling information.
The Basic Rate
Interface consists of two 64 Kbps B-channels and one 16 Kbps D- channel. Thus, a
Basic Rate user can have up to 128 Kbps service. The Primary Rate consists of 23
B-channels and one 64 Kpbs D-channel in the United States or 30 B-channels and 1
D-channel in Europe. Integrated Services Digital Network in concept is the
integration of both analog or voice data together with digital data over the
same network.
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LATA:
Local Access and Transport Area is a term in the U.S. for a geographic area
covered by one or more local telephone companies, which are legally referred to
as local exchange carriers (LECs).
A connection between two local exchanges within the LATA is referred to as
intraLATA. A connection between a carrier in one LATA to a carrier in another
LATA is referred to as interLATA. InterLATA is long-distance service. The
current rules for permitting a company to provide intraLATA or interLATA service
(or both) are based on the Telecommunications
Act of 1996.
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MCU:
Multipoint Control Unit. It is a unit that supports video conferencing
with multiple users at the same time. It also acts as a gateway between
the H.323 and the ISDN voice conference. The NJEDge.Net’s MCU will also
provide a video portal to the Access New Jersey network.
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MEMBER:
A college or university that has joined NJEDge.Net and ordered a circuit.
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MEMBER-to-MEMBER:
Communications traffic over the NJEDge.Net network that goes from one member to
another via the private virtual circuits of NJEDge.Net.
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MPLS:
stands for "Multiprotocol Label Switching". In an
MPLS network, incoming packets are assigned a "label" by a "label
edge router (LER)". Packets are forwarded along a "label switch
path (LSP)" where each "label switch router (LSR)" makes
forwarding decisions based solely on the contents of the label. At each
hop, the LSR strips off the existing label and applies a new label which tells
the next hop how to forward the packet.
Label Switch Paths (LSPs) are established by
network operators for a variety of purposes, such as to guarantee a certain
level of performance, to route around network congestion, or to create IP
tunnels for network-based virtual private networks. In many ways, LSPs are
no different than circuit-switched paths in ATM or Frame Relay networks, except
that they are not dependent on a particular Layer 2 technology.
An LSP can be
established that crosses multiple Layer 2 transports such as ATM, Frame Relay or
Ethernet. Thus, one of the true promises of MPLS is the ability to create
end-to-end circuits, with specific performance characteristics, across any type
of transport medium, eliminating the need for overlay networks or Layer 2 only
control mechanisms.
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MPEG:
MPEG (pronounced EHM-pehg), the Moving Picture Experts Group, develops standards
for digital
video and digital audio
compression.
It operates under the auspices of the International Organization for
Standardization (ISO).
The MPEG
standards are an evolving series, each designed for a different purpose.
To use MPEG video
files, you need a personal computer with sufficient processor speed, internal
memory, and hard disk space to handle and play the typically large MPEG file
(which has a file name suffix of .mpg). You also need an MPEG viewer or client
software that plays MPEG files. (Note that .mp3 file suffixes indicate MP3
(MPEG-1 audio layer-3) files, not MPEG-3 standard files.) You can download
shareware or commercial MPEG players from a number of sites on the Web.
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MULTI-HOMING:
Having multiple points of connection to the Internet. Multiple connections,
known as multi-homing, reduces the chance of loss of Internet access if one of
the connections fails. In addition to maintaining a reliable connection,
multi-homing allows an organization to perform load-balancing by managing the
traffic flow connecting to the Internet through any single connection.
Distributing the load through multiple connections optimizes performance.Multi-homed
networks are often connected to several different ISPs (Internet Service
Providers). Networks that are multi-homed to the Internet require a public
Autonomous System Number (ASN) from ARIN. Routers use BGP (Border Gateway
Protocol), a part of the TCP/IP protocol suite, to route between networks using
different protocols. In a multi-homed network, the router utilizes IBGP
(Internal Border Gateway Protocol) on the stub domain side, and EBGP (External
Border Gateway Protocol) to communicate with other routers.
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NAT:
NAT (Network Address Translation) is the translation of an Internet Protocol
address (IP
address) used within one network to a different IP address known within
another network. One network is designated the inside network and the other is
the outside. Typically, a company maps its local inside network addresses to one
or more global outside IP addresses and unmaps the global IP addresses on
incoming packets back into local IP addresses. This helps ensure security since
each outgoing or incoming request must go through a translation process that
also offers the opportunity to qualify or authenticate the request or match it
to a previous request. NAT also conserves on the number of global IP addresses
that a company needs and it lets the company use a single IP address in its
communication with the world.
NAT is included as
part of a router
and is often part of a corporate firewall.
Network administrators create a NAT table that does the global-to-local and
local-to-global IP address mapping. NAT can also be used in conjunction with
policy routing. NAT can be statically defined or it can be set up to dynamically
translate from and to a pool of IP addresses. Cisco's version of NAT lets an
administrator create tables that map:
A local IP address to
one global IP address statically
A local IP address to
any of a rotating pool of global IP addresses that a company may have
A local IP address
plus a particular TCP port
to a global IP address or one in a pool of them
A global IP address to
any of a pool of local IP addresses on a round-robin basis
NAT is described in
general terms in RFC 1631. which discusses NAT's relationship to Classless
Interdomain Routing (CIDR)
as a way to reduce the IP address depletion problem. NAT reduces the need for a
large amount of publicly known IP addresses by creating a separation between
publicly known and privately known IP addresses. CIDR aggregates publicly known
IP addresses into blocks so that fewer IP addresses are wasted. In the end, both
extend the use of IPv4 IP addresses for a few more years before IPv6
is generally supported.
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NIPS:
Network Internet Protocol Service is a new service offering from Verizon. It is
a Managed-IP service that utilizes an OC-192 national network backbone.
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PAT:
Port Address Translation. A function provided by some routers which allows
hosts on a LAN
to communicate with the rest of a network (such as the Internet)
without revealing their own private IP
address. All outbound packets have their IP address translated to the
routers external IP address. Replies come back to the router which then
translates them back into the private IP address of the original host for final
delivery.
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PVC:
A permanent virtual circuit (PVC) is a software-defined logical connection in a
network such as a frame
relay network. A feature of frame relay that makes it a highly flexible
network technology is that users (companies or clients of network providers) can
define logical connections and required bandwidth
between end points and let the frame relay network technology worry about how
the physical network is used to achieve the defined connections and manage the
traffic. In frame relay, the end points and a stated bandwidth called a
Committed Information Rate (CIR)
constitute a PVC, which is defined to the frame relay network devices. The
bandwidth may not exceed the possible physical bandwidth. Typically, multiple
PVCs share the same physical paths at the same time. To manage the variation in
bandwidth requirements expressed in the CIRs, the frame relay devices use a
technique called statistical multiplexing.
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QoS:
On the Internet and in other networks, QoS (Quality of Service) is the idea that
transmission rates, error rates, and other characteristics can be measured,
improved, and, to some extent, guaranteed in advance. QoS is of particular
concern for the continuous transmission of high-bandwidth
video and multimedia information. Transmitting this kind of content dependably
is difficult in public networks using ordinary "best effort"
protocols.
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RAS:
Registration Admission Status protocol. The communication protocol used to
convey registration, admission, and status messages between H.323 endpoints and
the gatekeeper.
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RFC:
A Request for Comments (RFC) is a formal document from the Internet Engineering
Task Force (IETF)
that is the result of committee drafting and subsequent review by interested
parties. Some RFCs are informational in nature. Of those that are intended to
become Internet standards, the final version of the RFC becomes the standard and
no further comments or changes are permitted. Change can occur, however, through
subsequent RFCs that supersede or elaborate on all or parts of previous RFCs
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SEGP:
Sponsored Educational Group Participant. An Internet 2 category of
membership for aggregates of organizations brought together in a statewide
network.
SVC:
In a network, a switched virtual circuit (SVC) is a temporary virtual
circuit that is established and maintained only for the duration of a data
transfer session. A permanent virtual circuit (PVC)
is a continuously dedicated virtual circuit. A virtual circuit is one that
appears to be a discrete, physical circuit available only to the user but that
is actually a shared pool of circuit resources used to support multiple users as
they require the connections. Switched virtual circuits are part of an X.25
network. Conceptually, they can also be implemented as part of a frame
relay network.
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THE
QUILT: Over 15 non-profit research and education network organizations,
which provide network resources for thousands of U.S research and education
institutions, have pooled resources to form the Quilt. The University
Corporation for Advanced Internet Development (UCAID), a Washington, DC- based
organization that promotes networking for education and research, is providing
organizational support for The Quilt.
The Quilt’s initial
objectives include: to provide a forum for best practices related to implementation of fiber-optic
network infrastructure,
to support improved end-to-end network performance through uniform standards to
measure and assess performance, and
to aggregate the Internet services buying power of The Quilt’s participants.
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UBR:
Unspecified Bit Rate A form of ATM transmission in which an information stream
is supported on whatever bandwidth is available after other connection types
have been satisfied. No congestion control is provided. UBR is commonly used to
support information streams originating in LAN switches with ATM uplinks.
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VBNS: The vBNS (very
high-speed Backbone Network Service) is a network that interconnects a number of
supercomputer
centers in the United States and is reserved for science applications
requiring the massive computing that supercomputers can provide. Scientists at
the supercomputer centers and other locations apply for time on the
supercomputers and use of the vBNS by describing their projects to a committee
that apportions computer time and vBNS resources. The vBNS and the supercomputer
centers were initiated and are maintained by the National Science Foundation
(NSF). The vBNS has recently become part of the infrastructure of Internet2.
A new NFS-funded initiative is developing an advanced network infrastructure
referred to as the National Technology Grid.
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VLSM: Variable length
sub-net mask, which is the practice of multiple logical network in one
octet-aligned address range using power-of-two division.
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