A device that allows wireless
equipped computers and other devices to communicate
with a wired network. Also used to expand the range of a wireless network.
A group of wireless devices communicating directly with each other
without the use of an access point.
A device used to boost the strength of an electronic or optical signal, which
is weakened (attenuated) as it passes through the transport network. Amplifiers
add gain to the signal by an amount e
qual to the loss in the previous section
of the network since last amplification.
Asymmetric Digital Subscriber Line (ADSL)
A new technology that allows more data to be sent over existing copper telephone
lines. ADSL supports data rates of from 1.5 to 9 Mb
ps when receiving data (known
as the downstream rate) and from 16 to 640 Kbps when sending data (known as
the upstream rate).
Asynchronous Transfer Mode (ATM)
A method of sending audio, visual and computer data at the same time over one
The part of a network that connects most of the systems and networks together,
and handles the most data.
Data transmitted on your wireless network that keeps the network synchronized.
A device that connects two differ
ent kinds of local networks, such as a wireless
network to a wired Ethernet network.
A transmission channel usually carrying a tremendous amount of information.
A communications channel with a bandwidth sufficiently large to carry voice,
video on a signal channel. Any voice communications channel having
a bandwidth greater than a voice
An incorrect packet broadcast onto a network that causes multiple hosts to
respond all at once, typically with equally incor
rect packets which causes the
storm to grow exponentially in severity.
A shared or assigned memory area that is used to support and coordinate different
computing and networking activities so one isn't held up by the other.
A way of doing
data transmission, usually faster than normal transmission mode,
in which a continuous block is transferred between main memory and an
device without interruption until the transfer has been completed. Characteristically,
burst mode is sustai
nable for only limited periods of time under special conditions.
A device that connects a computer to the cable television network, which in
turn connects to the Internet.
A computed value which is dependent upon the contents of a
packet. This value
is sent along with the packet when it is transmitted. The receiving system computes
a new checksum based upon the received data and compares this value with the
one sent with th
packet. If the two values are the same, the receiver has a
high degree of confidence that the data was received correctly.
A communications paradigm in which a dedicated communication path is
between two hosts, and on which all packets travel. The telephone system is
an example of a
circuit switched network.
A computer system or process that requests a service of another computer system
or process. A workstation requesting the contents of a file from a file server
is a client of the file server.
Algorithm that minim
izes the redundancy in the signal to be transmitted.
Congestion occurs when the offered load exceeds the capacity of a data
The data communication method in which communication proceeds through three
defined phases: connection establishment, data transfer, connection release.
TCP is a connection
The process of concealing the contents of a message from all except those who
know the key. Cryptography is used to protect e
ail messages, credit card
and corporate data. As the Internet and other forms of electronic communication
become more prevalent, electronic security is also becoming increasingly important.
A collection of data that is organized so th
at its contents can easily be accessed,
managed, and updated
A device that forwards Internet traffic from your local area network.
A routing table entry which is used to direct packets addressed to networks
not explicitly list
ed in the routing table.
DHCP (Dynamic Host Configuration Protocol)
A protocol that lets one device on a local network, known as a DHCP server,
assign temporary IP addresses to the other network devices, typically computers.
DNS (Domain Name Server)
address of your ISP's server, which translates the names of websites
into IP addresses.
The technique used by layered protocols in which a layer adds header information
to the protocol data unit (PDU) from the layer above.
Encryption is the manipulation of data to prevent accurate interpretation by
all but those for whom the data is intended. There are many types of data encryption,
and they are the basis of network security.
An IEEE standard network protocol that s
pecifies how data is placed on and
retrieved from a common transmission medium.
The ability of a system to respond gracefully to an unexpected hardware or
software failure. There are many levels of fault tolerance, the lowest being
ity to continue operation in the event of a power failure.
A firewall is any of security schemes that prevent unauthorized users from
gaining access to a computer network or that monitor transfers of information
to and from the network.
A standard protocol for sending files between computers over a TCP/IP network
and the Internet. FTP is usually the name of the program the user invokes to
execute the protocol.
A piece of a packet. When a router is forwarding an
IP packet to a network
that has a maximum packet size smaller than the packet size, it is forced to
break up that packet into multiple fragments. These fragments will be reassembled
by the IP layer at the destination host.
The ability of a net
working device to receive and transmit data simultaneously.
Full duplex is sometimes called "Echo On" by some communications programs.
A device that interconnects networks with different, incompatible communications
protocols. The term "router" is
now used in place of the original
definition of "gateway". Currently, a gateway is a communications
device/program which passes data between networks having similar functions but
dissimilar implementations. This should not be confused with a protocol conve
By this definition, a router is a layer 3 (network layer) gateway, and a mail
gateway is a layer 7 (application layer) gateway.
Data transmission that can occur in two directions over a single line, but
only one direction at a time.
A slang term for a computer enthusiast. Also refers to individuals who gain
unauthorized access to computer systems for the purpose of stealing and corrupting
A computer that allows users to communicate with other host computers on a
Individual users communicate by using application programs, such as
electronic mail, Telnet and FTP.
A device connected to several other devices. In ARCnet, a hub is used to connect
several computers together. In a message handling service, a hub is
the transfer of messages across the network.
HTTP (HyperText Transport Protocol)
The communications protocol used to connect to servers on the World Wide Web.
IEEE (The Institute of Electrical and Electronics Engineers)
An independent institute th
at develops networking standards.
ISP (Internet Service Provider)
A company that provides access to the Internet.
The amount of time it takes a packet to travel from source to destination.
Together, latency and bandwidth define the speed and capaci
ty of a network.
MAC (Media Access Control) Address
A MAC address is the hardware address of a device connected to a shared network
The material used to support the transmission of data. This can be copper wire,
coaxial cable, optical fib
or electromagnetic wave (as in microwave).
Sending data to a group of destinations at once. The ability of one network
node to send identical data to a number of end servers on the multicast backbone.
For large amounts of data, IP multicastin
g is more efficient than normal Internet
transmissions because the server can broadcast a message to multiple recipients
NAT (Network Address Translation)
NAT technology translates IP addresses of the local area network to a different
dress for the Internet.
A network junction or connection point, typically a computer or work station.
Thin filaments of glass through which light beams are transmitted. Enormous
power consumption, small space, lig
to electromagnetic interference characterize this transport media.
A unit of data transmitted over a network.
Ping (Packet INternet Groper)
An Internet utility used to determine whether a particular IP address is online.
(Post Office Protocol 3)
A standard protocol used to retrieve e
mail stored on a mail server.
The connection point on a computer or networking device used for plugging in
a cable or an adapter.
Equipment that receives a low
power signal, pos
sibly converting it from
light to electrical form, amplifying it or retiming and reconstructing it for
transmission. It may need to be reconverted to light for retransmission.
45 (Registered Jack
An Ethernet connector that holds up to eight wires.
The ability to take a wireless device from one access point's range to another
without losing the connection.
A networking device that connects multiple networks together, such as a local
network and the Internet.
SMTP (Simple Mail Transfer P
The standard e
mail protocol on the Internet.
Static IP Address
A fixed address assigned to a computer or device that is connected to a network.
1. A device that is the central point of connection for computers and other
devices in a networ
k, so data can be shared at full transmission speeds.
2. A device for making, breaking, or changing the connections in an electrical
TCP (Transmission Control Protocol)
A network protocol for transmitting data that requires acknowledgement from
e recipient of data sent.
TCP/IP (Transmission Control Protocol/Internet Protocol)
A network protocol for transmitting data that requires acknowledgement from
the recipient of data sent.
A user command and TCP/IP protocol used for accessing remote
The amount of data moved successfully from one node to another in a given time
To replace existing software or firmware with a newer version.
To transmit a file over a network.
Voice over IP (VoIP)
VoIP is voice
communications transmitted over the Internet.
WLAN (Wireless Local Area Network)
A group of computers and associated devices that communicate with each other