DHCP uses the concept of a "lease" or amount of time that a given IP address
will be valid for a computer. The lease time can vary depending on how long a
user is likely to require the Internet connection at a particular location. It's espe-
cially useful in education and other environments where users change fre-
quently. Using very short leases, DHCP can dynamically reconfigure networks
in which there are more computers than there are available IP addresses.
DHCP supports static addresses for computers containing Web servers that
need a permanent IP address.
Dynamic IP Address - An IP address that is automatically assigned to a client
station in a TCP/IP network, typically by a DHCP server. Network devices that
serve multiple users, such as servers and printers, are usually assigned static IP
addresses.
Dynamic Routing - The ability for a router to forward data via a different route
based on the current conditions of the communications circuits. For example, it
can adjust for overloaded traffic or failing lines and is much more flexible than
static routing, which uses a fixed forwarding path.
Ethernet - IEEE standard network protocol that specifies how data is placed on
and retrieved from a common transmission medium. Has a transfer rate of 10
Mbps. Forms the underlying transport vehicle used by several upper-level proto-
cols, including TCP/IP and XNS.
Fast Ethernet - A 100 Mbps technology based on the 10Base-T Ethernet
CSMA/CD network access method.
FTP (File Transfer Protocol) - A protocol used to transfer files over a TCP/IP net-
work (Internet, UNIX, etc.). For example, after developing the HTML pages for a
Web site on a local machine, they are typically uploaded to the Web server using
FTP.
FTP includes functions to log onto the network, list directories and copy files. It
can also convert between the ASCII and EBCDIC character codes. FTP operations
can be performed by typing commands at a command prompt or via an FTP util-
ity running under a graphical interface such as Windows. FTP transfers can also
be initiated from within a Web browser by entering the URL preceded with ftp://.
Unlike e-mail programs in which graphics and program files have to be
"attached," FTP is designed to handle binary files directly and does not add the
overhead of encoding and decoding the data.
CAT 3 - ANSI/EIA (American National Standards Institute/Electronic
Industries Association) Standard 568 is one of several standards that specify
"categories" (the singular is commonly referred to as "CAT") of twisted pair
cabling systems (wires, junctions, and connectors) in terms of the data rates
that they can sustain. CAT 3 cable has a maximum throughput of 16 Mbps and
is usually utilized for 10BaseT networks.
CAT 5 - ANSI/EIA (American National Standards Institute/Electronic
Industries Association) Standard 568 is one of several standards that specify
"categories" (the singular is commonly referred to as "CAT") of twisted pair
cabling systems (wires, junctions, and connectors) in terms of the data rates
that they can sustain. CAT 5 cable has a maximum throughput of 100 Mbps
and is usually utilized for 100BaseTX networks.
CAT 5e - The additional cabling performance parameters of return loss and far-
end crosstalk (FEXT) specified for 1000BASE-T and not specified for
10BASE-T and 100BASE-TX are related to differences in the signaling imple-
mentation. 10BASE-T and 100BASE-TX signaling is unidirectional-signals
are transmitted in one direction on a single wire pair. In contrast, Gigabit
Ethernet is bi-directional-signals are transmitted simultaneously in both direc-
tions on the same wire pair; that is, both the transmit and receive pair occupy
the same wire pair .
CPU (Central Processing Unit) - The computing part of the computer. Also
called the "processor," it is made up of the control unit and ALU.
Data Packet - One frame in a packet-switched message. Most data communi-
cations is based on dividing the transmitted message into packets. For example,
an Ethernet packet can be from 64 to 1518 bytes in length.
Default Gateway - The routing device used to forward all traffic that is not
addressed to a station within the local subnet.
DHCP (Dynamic Host Configuration Protocol) - A protocol that lets network
administrators manage centrally and automate the assignment of Internet
Protocol (IP) addresses in an organization's network. Using the Internet's set of
protocol (TCP/IP), each machine that can connect to the Internet needs a
unique IP address. When an organization sets up its computer users with a con-
nection to the Internet, an IP address must be assigned to each machine.
Without DHCP, the IP address must be entered manually at each computer and,
if computers move to another location in another part of the network, a new IP
address must be entered. DHCP lets a network administrator supervise and dis-
tribute IP addresses from a central point and automatically sends a new IP
address when a computer is plugged into a different place in the network.
EtherFast
®
10/100/1000 8+1 Workgroup GigaSwitch Starter Kit
Instant Gigabit Series
70
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