Linksys WAP11 v.2.6 User Manual page 24

being held up by the other. In order for a buffer to be effective, the size of the
buffer and the algorithms for moving data into and out of the buffer need to be
considered by the buffer designer. Like a cache, a buffer is a "midpoint holding
place" but exists not so much to accelerate the speed of an activity as to sup-
port the coordination of separate activities.
CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) - In local
area networking, this is the CSMA technique that combines slotted time-divi-
sion multiplexing with carrier sense multiple access/collision detection
(CSMA/CD) to avoid having collisions occur a second time. This works best if
the time allocated is short compared to packet length and if the number of sit-
uations is small.
CSMA/CD (Carrier Sense Multiple Access/Collision Detection) - The LAN
access method used in Ethernet. When a device wants to gain access to the net-
work, it checks to see if the network is quiet (senses the carrier). If it is not, it
waits a random amount of time before retrying. If the network is quiet and two
devices access the line at exactly the same time, their signals collide. When the
collision is detected, they both back off and each wait a random amount of time
before retrying.
Database - A database is a collection of data that is organized so that its con-
tents can easily be accessed, managed, and updated.
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.
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.
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Instant Wireless Series
®
Wireless Network Access Point
DHCP supports static addresses for computers containing Web servers that
need a permanent IP address.
Download - To receive a file transmitted over a network. In a communications
session, download means receive, upload means transmit.
Driver - A workstation or server software module that provides an interface
between a device and the upper-layer protocol software running in the comput-
er; it is designed for a specific device, and is installed during the initial instal-
lation of a network-compatible client or server operating system.
DSSS (Direct-Sequence Spread-Spectrum) - DSSS generates a redundant bit
pattern for all transmitted data. This bit pattern is called a chip (or chipping
code). Even if one or more bits in the chip are damaged during transmission,
statistical techniques embedded in the receiver can recover the original data
without the need for retransmission. To an unintended receiver, DSSS appears
as low power wideband noise and is rejected (ignored) by most narrowband
receivers. However, to an intended receiver (i.e. another wireless LAN end-
point), the DSSS signal is recognized as the only valid signal, and interference
is inherently rejected (ignored).
DTIM (Delivery Traffic Indication Message) - A DTIM field is a countdown
field informing clients of the next window for listening to broadcast and mul-
ticast messages. When the AP has buffered broadcast or multicast messages for
associated clients, it sends the next DTIM with a DTIM Interval value. AP
Clients hear the beacons and awaken to receive the broadcast and multicast
messages.
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.
Encryption - A security method that applies a specific algorithm to data in
order to alter the data's appearance and prevent other devices from reading the
information.
ESS (Extended Service Set) - A set of more than two or more BSSs (multiple
access points) forming a single network.
Ethernet - IEEE standard network protocol that specifies how data is placed
on and retrieved from a common transmission medium. Has a transfer rate of
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