PPPoE Mode
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Glossary
- ADSL (Asymmetric Digital Subscriber Line)
- A new technology that allows more data to be sent over existing copper
telephone lines (POTS or "Plain Old Telephone Service"). ADSL is more
than 275 times faster than a 28.8 modem and up to 4 times faster than
a T1 connection. That's really, really fast. DSL (ADSL, SDSL) technology
uses your ordinary phone line but doesn't tie it up. You can access the
Internet while you are telephoning or faxing. ADSL requires a special
ADSL modem which allows your PC to connect to a remote site using a network
protocol such as IP or IPX. Your HomeConnect ADSL Modem Dual Link contains
one ADSL modem port, which is the WAN (Wide Area Network) interface. ADSL
service runs between your home and your service provider, who then uses
ATM technology to speed communications to more distant points.
- ATM (Asynchronous Transfer Mode)
- A network technology based on transferring data in small cells or packets
of a fixed size. The small cell size allows ATM equipment to transmit
video, audio, and computer data over the same network without any type
of data consuming the entire capacity of the line. ATM differs from TCP/IP,
where message packets take different routes from source to endpoint. ATM
defines connections by two main parameters: Virtual Path Identifier (VPI)
and Virtual Channel Identifier (VCI). VPI and VCI are defined in this
Glossary. Your service provider will tell you what VPI and VCI values
you must use in your Dual Link in order to properly connect to their service.
- Bridging, Bridged
- In networking, bridging is the process of moving a packet (or piece)
of data from source to destination. A bridge is a mechanism which forwards
packets between different networks based on hardware-level addresses.
Your HomeConnect modem automatically maintains a forwarding table that
contains information needed to correctly route data, so you don't need
to manually add or delete entries as your home network configuration changes.
- Connector (or Jack)
- The part of a cable that plugs into a port or interface to connect
one device to another.
- Console Port
- The console port on your Dual Link can be matched to the Com port (Com1,
Com2...) on your computer using the DB-9 serial cable provided. On the
ADSL Modem Dual Link, it is typically used only in the case of disaster
recovery.
- DHCP (Dynamic Host Configuration Protocol)
- This allows a device to have a different IP address every time it connects
to the network or, in some cases, to change while it is still connected.
The software keeps track of IP addresses. This allows a new computer to
be added to a network without having to manually assign it a unique IP
address.
- DIP switch
- A series of tiny switches built into circuit boards. DIP switches let
you configure a circuit board to conform to a particular application.
In the case of your Dual Link modem, the DIP switch is reserved and all
toggle switches should be left in the Off position.
- DSL (Digital Subscriber Line)
- The two main categories of DSL currently are the ADSL (Asynchronous
DSL) and SDSL (Synchronous DSL). DSL technologies pack data onto copper
wires. They are used for connections from a telephone switching station
to a home or office, not between switching stations. DSL is similar to
ISDN in that both operate over existing copper telephone lines (POTS)
and both require the short runs to a central telephone office (usually
less than 20,000 feet). But DSL offers much higher speeds.
- Encapsulation
- In networking, encapsulation means wrapping a data set in a protocol
header. This allows one network to send its data via another network's
connections.
- Ethernet
- Ethernet is a LAN (local area network) protocol that was developed
by Xerox Corporation in cooperation with DEC and Intel in 1976. It is
one of the most widely implemented LAN standards. Its function is to move
data packets from one computer to another.
- Flash Memory
- An area on the modem where basic information necessary to operate the
modem is stored. In your modem Dual Link, it contains a program with the
extension ".nac" which must be easy to update but not easy to erase. A
utility provided on your installation CD, if you install it on your PC,
can search for any updates to the Nac file from the 3Com web site.
- Host
- The word Host has several different meanings in the computer industry.
The "host" can be referred to as the computer system that is accessed
remotely by modem over telephone lines by a user sitting at a remote terminal.
It has also come to mean any computer connected to a TCP/IP network, including
the Internet. Each Host has a unique IP address. "To host", on the other
hand, means to provide the infrastructure for a computer service, as,
for example, to "host" Web servers, where the hardware, software and communication
lines are provided and controlled by the company providing the server
while the content on the server is controlled by the user.
- Hub
- A conduit for information between devices that are part of a network.
A hub contains a number of ports which all participating devices (computers,
printers, scanners, etc.) in the network plug into. The hub then receives
and directs information to all segments of the LAN.
- LAN
- A computer network that spans a relatively small area. Most LANs are
confined to a single building or group of buildings. However, one LAN
can be connected to other LANs over any distance via telephone lines and
radio waves. A system of LANs connected in this way is called a wide-area
network (WAN). Computers connected to a LAN are able to share, not only
data, but also expensive devices, such as laser printers and scanners.
Ethernet LANs are most common for PCs. Data transmission is very fast
on a LAN, but the distances and numbers of computers that can be connected
are limited.
- LED (light emitting diode)
- An electronic device or signal that lights up when electricity is passed
through it. Your Dual Link modem uses LEDs to indicate the status of important
operations.
- Modem (modulator-demodulator)
- A modem is a device or program that enables a computer to transmit data
over telephone lines. The modem converts data which is stored digitally
(in the computer) to analog data (which is required for transmission over
telephone lines) and vice versa. Simply stated, "digital" data is based
on discrete "on-off" switching (1 and 0) whereas analog data consists
of infinitely variable data, such as sound waves.
- Nac file
- A "Nac file" is a file with the extension .nac. The file extension
was coined by U.S. Robotics from the words Network Application Code
or Network Application Card. It contains information essential to network
communications and resides in the Flash memory of your modem Dual Link.
If you choose to install the "Instant Update" utility from your modem's
installation CD, the utility will search for and download from the 3Com
web site any update to the Nac file. Once you've received an updated
Nac file, you would install to the modem using the DL manager.
- NIC (network interface card)
- An expansion board or adapter that you install or insert into a computer
in order to make it capable of communicating to a network. A common example
is an Ethernet LAN adapter.
- IP (Internet Protocol)
- Specifies the format of packets (pieces of data) and the addressing
scheme. Most networks combine IP with a higher-level protocol called Transport
Control Protocol (TCP), which establishes a virtual connection between
a destination and a source. IP by itself is like a postal system. Using
it, you can "address a package and drop it in the mail," but there's no
direct link between you and the recipient. TCP/IP, on the other hand,
establishes a connection between two hosts so that they can send messages
back and forth for a period of time.
- IP Address
- An identifier for a computer or device on a TCP/IP network. Networks
using the TCP/IP protocol route messages based on the IP address of the
destination. The format of an IP address is a 32-bit numeric address written
as four numbers separated by periods. Each number can be zero to 255.
For example, 1.160.10.240 could be an IP address.
- Jack
- The part of a cable that plugs into a port or interface to connect one
device to another.
- Packet
- A piece of a message transmitted over a packet-switching network. In
IP networks, packets are often called datagrams. In a packet-switching
network, messages are divided into "packets" which are addressed and sent
separately and matched up at their destination.
- PIN
- A male lead (a thin metal foot or prong) on a connector.
- POTS
- Plain Old Telephone Service.
- PPP (Point-to-Point Protocol)
- A method of connecting a computer to the Internet. Other methods are
Bridged (RFC-1483) and PPPoE. PPP is one of the most widely used data
link protocols in networks. It lets a computer connect to the Internet
with a standard dial-up telephone line and a high-speed modem. In order
to use PPP, your service provider must support it.
- PPPoE (Point-to-Point Protocol over Ethernet)
- PPPoE was developed to allow users to connect a LAN to connect to the
Internet over a single link (Virtual Circuit). In PPP and RFC-1483, connections
exist between the HomeConnect ADSL Modem Dual Link and the ISP, while
in PPPoE, the link is to the individual PCs. So the user on the LAN can
select when to connect to a particular service by "logging in" to that
service (sort of like placing a telephone call.) Choosing which of the
protocols to use is not up to the user but dependent on the ISP. Ask your
service provider if it's available.
- Protocol
- An agreed-upon format for transmitting data between two devices. The
protocol determines the type of error-checking to be used, the data compression
method, how the sending device will indicate that it has finished sending
a message, and how the receiving device will indicate that it has received
a message. From a user's point of view, the only interesting aspect about
protocols is that your computer or device must support the right ones
if you want to communicate with other computers.
- PVC (permanent virtual circuit)
- A virtual circuit that is permanently available. The only difference
between a PVC and a switched virtual circuit (SVC) is that an SVC must
be re-established each time data is to be sent. Once the data has been
sent, the SVC disappears. PVCs are more efficient for connections between
hosts that communicate frequently.
- RFC
- Short for Request for Comments, a series of notes about the Internet,
started in 1969. An RFC can be submitted by anyone. Eventually, if it
gains enough interest, it may evolve into an Internet standard. RFC-1483
is the protocol traditionally used for ATM networks. Each RFC is designated
by an RFC number. Once published, an RFC never changes. Modifications
to an original RFC are assigned a new RFC number.
- RFC-1483
- This is a protocol used for ATM networks. It's a very efficient channel
or path for data transmission. It differs from PPPoE and PPP in that it
doesn't provide any built-in negotiation for addresses or connection.
- RJ-11 Jack
- Short for Registered Jack-11, a four- or six-wire connector used primarily
to connect telephone equipment in the United States. RJ-11 connectors
are also used to connect some types of local-area networks (LANs), although
RJ-45 connectors are more common.
- RJ-45 Jack
- Short for Registered Jack-45, an eight-wire connector used commonly
to connect computers onto local-area networks (LANs), especially Ethernets.
RJ-45 connectors look similar to the ubiquitous RJ-11 connectors used
for connecting telephone equipment, but they are somewhat wider.
- SDSL (symmetric digital subscriber line)
- SDSL is called symmetric because it supports the same data rates for
upstream and downstream traffic. A similar technology that supports different
data rates for upstream and downstream data is called asymmetric digital
subscriber line (ADSL). ADSL is more popular in North America, whereas
SDSL is being developed primarily in Europe
- TCP (Transmission Control Protocol)
- TCP is one of the main protocols in TCP/IP networks. Whereas the IP
protocol deals only with packets, TCP enables two hosts to establish a
connection and exchange streams of data. TCP guarantees delivery of data
and also guarantees that packets will be delivered in the same order in
which they were sent.
- TCP/IP (Transmission Control Protocol/Internet Protocol)
- The communications protocols used to connect hosts on the Internet.
TCP/IP is built into the UNIX operating system and is used by the Internet,
making it the de facto standard for transmitting data over networks. Even
network operating systems that have their own protocols support TCP/IP.
- Telecommuting
- A term coined in the early 1970s to describe a geographically-dispersed
office where workers can work at home on a computer and transmit data
and documents to a central office via telephone lines.
- USB (Universal Serial Bus)
- A new external bus standard that supports very fast data transfer rates.
A single USB port can be used to connect up to 127 peripheral devices.
Manufacturers are including USB ports in more and more new computers.
- VCI (Virtual Circuit Identifier)
- A virtual circuit is a connection between two devices that acts as though
it's a direct connection even though it may physically be circuitous.
The term is used most frequently to describe connections between two hosts
in a packet-switching network. The two hosts can communicate as though
they have a dedicated connection even though the packets might actually
travel very different routes before arriving at their destination.
- VPI (Virtual Path Identifier)
- "Virtual path" refers, in networking, to the location of a file or directory
on a server being accessed remotely via the Web. The VPI is the address
of the file.
- WAN (Wide Area Network)
- A computer network that spans a relatively large geographical area.
Typically, a WAN consists of two or more local-area networks (LANs). Computers
connected to a wide-area network are often connected through public networks,
such as the telephone system. They can also be connected through leased
lines (cable) or satellites. The largest WAN in existence is the Internet.
- Workstation
- (1). In networking, workstation refers to any computer connected to
a local-area network. It could be a "workstation" (definition 2) or a
personal computer (PC). (2). A "workstation" in a second sense generally
means a computer that is capable of a moderate amount of computing power
and high graphics capabilities. It is somewhere in power between a PC
and a mini-computer, although the lines are becoming more and more blurred.
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