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A

Access Point
An access point is the communication hub for the devices on a WLAN,
providing a connection or bridge between wireless and wired network
devices. It supports a Wireless Networking Framework called
Infrastructure Mode.

When one access point is connected to wired network and supports a set
of wireless stations, it is referred to as a basic service set (BSS).
An extended service set (ESS) is created by combining two or more BSSs.


Ad hoc Mode
Ad hoc mode is a Wireless Networking Framework in which stations
communicate directly with each other. It is useful for quickly
establishing a network in situations where formal infrastructure is not
required.

Ad hoc mode is also referred to as peer-to-peer mode or an independent basic service set (IBSS).

AES
The Advanced Encryption Standard (AES) is a symmetric 128-bit block
data encryption technique developed to replace DES encryption. AES
works at multiple network layers simultaneously.



B

Basic Rate Set
The basic rate set defines the transmission rates that are mandatory
for any station wanting to join this wireless network. All stations
must be able to receive data at the rates listed in this set.

Beacon
Beacon frames provide the "heartbeat" of a WLAN, announcing the
existence of the network, and enabling stations to establish and
maintain communications in an orderly fashion. It carries the following
information (some of which is optional):

The Timestamp is used by stations to update their local clock, enabling synchronization among all associated stations.
The Beacon interval defines the amount of time between transmitting
beacon frames. Before entering power save mode, a station needs the
beacon interval to know when to wake up to receive the beacon.
The Capability Information lists requirements of stations that want to
join the WLAN. For example, it indicates that all stations must use
WEP.
The Service Set Identifier (SSID).
The Basic Rate Set is a bitmap that lists the rates that the WLAN supports.
The optional Parameter Sets indicates features of the specific
signaling methods in use (such as frequency hopping spread spectrum,
direct sequence spread spectrum, etc.).
The optional Traffic Indication Map (TIM) identifies stations, using power saving mode, that have data frames queued for them.
Bridge
A connection between two local area networks (LANs) using the same protocol, such as Ethernet or IEEE 802.1x.

Broadcast
A Broadcast sends the same message at the same time to everyone. In
wireless networks, broadcast usually refers to an interaction in which
the access point sends data traffic in the form of IEEE 802.1x Frames
to all client stations on the network.

Some wireless security modes distinguish between how unicast,
multicast, and broadcast frames are encrypted or whether they are
encrypted.


BSS
A basic service set (BSS) is an Infrastructure Mode Wireless Networking
Framework with a single access point. Also see extended service set
(ESS) and independent basic service set (IBSS).

BSSID
In Infrastructure Mode, the Basic Service Set Identifier (BSSID) is the
48-bit MAC address of the wireless interface of the Access Point.


C

CCMP
Counter mode/CBC-MAC Protocol (CCMP) is an encryption method for
802.11i that uses AES. It employs a CCM mode of operation, combining
the Cipher Block Chaining Counter mode (CBC-CTR) and the Cipher Block
Chaining Message Authentication Code (CBC-MAC) for encryption and
message integrity.

AES-CCMP requires a hardware coprocessor to operate.

CGI
The Common Gateway Interface (CGI) is a standard for running external
programs from an HTTP server. It specifies how to pass arguments to the
executing program as part of the HTTP request. It may also define a set
of environment variables.

A CGI program is a common way for an HTTP server to interact
dynamically with users. For example, an HTML page containing a form can
use a CGI program to process the form data after it is submitted.

Channel
The Channel defines the portion of the radio spectrum the radio uses
for transmitting and receiving. Each 802.11 standard offers a number of
channels, dependent on how the spectrum is licensed by national and
transnational authorities such as the Federal Communications Commission
(FCC), the European Telecommunications Standards Institute (ETSI), the
Korean Communications Commission, or the Telecom Engineering Center
(TELEC).

CSMA/CA
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is a
low-level network arbitration/*******ion protocol. A station listens to
the media and attempts to transmit a packet when the channel is quiet.
When it detects that the channel is idle, the station transmits the
packet. If it detects that the channel is busy, the station waits a
random amount of time and then attempts to access the media again.

CSMA/CA is the basis of the IEEE 802.11e Distributed Control Function (DCF). See also RTS and CTS.

The CSMA/CA protocol used by 802.11 networks is a variation on CSMA/CD
(used by Ethernet networks). In CSMA/CD the emphasis is on collision
detection whereas with CSMA/CA the emphasis is on collision avoidance.

CTS
A clear to send (CTS) message is a signal sent by an IEEE 802.11 client
station in response to an request to send (RTS) message. The CTS
message indicates that the channel is clear for the sender of the RTS
message to begin data transfer. The other stations will wait to keep
the air waves clear. This message is a part of the IEEE 802.11 CSMA/CA
protocol


D

DCF
The Distribution Control Function is a component of the IEEE 802.11e
Quality of Service (QoS) technology standard. The DCF coordinates
channel access among multiple stations on a wireless network by
controlling wait times for channel access. Wait times are determined by
a random backoff timer which is configurable by defining minimum and
maximum *******ion windows

DHCP
The Dynamic Host Configuration Protocol (DHCP) is a protocol specifying
how a central server can dynamically provide network configuration
information to clients. A DHCP server "offers" a "lease" (for a
pre-configured period of time-see Lease Time) to the client system. The
information supplied includes the client's IP addresses and netmask
plus the address of its DNS servers and Gateway.

DNS
The Domain Name Service (DNS) is a general-purpose query service used
for translating fully-qualified names into Internet addresses. A
fully-qualified name consists of the hostname of a system plus its
domain name. For example, www is the host name of a Web server and www.devicescape.com is the fully-qualified name of that server. DNS translates the domain name www.devicescape.com to some IP address, for example 66.93.138.219.

A domain name identifies one or more IP addresses. Conversely, an IP address may map to more than one domain name.

A domain name has a suffix that indicates which top level domain (TLD)
it belongs to. Every country has its own top-level domain, for example
.de for Germany, .fr for France, .jp for Japan, .tw for Taiwan, .uk for
the United Kingdom, .us for the U.S.A., and so on. There are also .com
for commercial bodies, .edu for educational institutions, .net for
network operators, and .org for other organizations as well as .gov for
the U. S. government and .mil for its armed services.

DOM
The ******** Object Model (DOM) is an interface that allows programs
and ******s to dynamically access and update the *******, structure,
and style of ********s. The DOM allows you to model the objects in an
HTML or XML ******** (****, links, images, tables), defining the
attributes of each object and how they can be manipulated.


DTIM
The Delivery Traffic Information Map (DTIM) message is an element
included in some Beacon frames. It indicates which stations, currently
sleeping in low-power mode, have data buffered on the Access Point
awaiting pick-up. Part of the DTIM message indicates how frequently
stations must check for buffered data.


E

EAP
The Extensible Authentication Protocol (EAP) is an authentication
protocol that supports multiple methods, such as token cards, Kerberos,
one-time passwords, certificates, public key authentication, and smart
cards.

Variations on EAP include EAP Cisco Wireless (LEAP), Protected EAP (PEAP), EAP-TLS, and EAP Tunnelled TLS (EAP-TTLS).

EDCF
Enhanced Distribution Control Function is an extenstion of DCF. EDCF, a
component of the IEEE Wireless Multimedia (WMM) standard, provides
prioritized access to the wireless medium

ESS
An extended service set (ESS) is an Infrastructure Mode Wireless
Networking Framework with multiple access points, forming a single
subnetwork that can support more clients than a basic service set
(BSS). Each access point supports a number of wireless stations,
providing broader wireless coverage for a large space, for example, an
office.

Ethernet
Ethernet is a local-area network (LAN) architecture supporting data
transfer rates of 10 Mbps to 1 Gbps. The Ethernet specification is the
basis for the IEEE 802.3 standard, which specifies the physical and
lower software layers. It uses the CSMA/CA access method to handle
simultaneous demands.

Ethernet supports data rates of 10 Mbps, Fast Ethernet supports 100
Mbps, and Gigabit Ethernet supports 1 Gbps. Its cables are classified
as "XbaseY", where X is the data rate in Mbps and Y is the category of
cabling. The original cable was 10base5 (Thicknet or "Yellow Cable").
Some others are 10base2 (Cheapernet), 10baseT (Twisted Pair), and
100baseT (Fast Ethernet). The latter two are commonly supplied using
CAT5 cabling with RJ-45 connectors. There is also 1000baseT (Gigabit
Ethernet).

ERP
The Extended Rate Protocol refers to the protocol used by IEEE 802.11g
stations (over 20 Mbps transmission rates at 2.4GHz) when paired with
Orthogonal Frequency Division Multiplexing (OFDM). Built into ERP and
the IEEE 802.11g standard is a scheme for effective interoperability of
IEEE 802.11g stations with IEEE 802.11b nodes on the same channel.

Legacy IEEE 802.11b devices cannot detect the ERP-OFDM signals used by
IEEE 802.11g stations, and this can result in collisions between data
frames from IEEE 802.11b and IEEE 802.11g stations.

If there is a mix of 802.11b and 802.11g nodes on the same channel, the
IEEE 802.11g stations detect this via an ERP flag on the access point
and enable request to send (RTS) and clear to send (CTS) protection
before sending data.


F

Frame
A Frame consists of a discrete portion of data along with some
de******ive ****-information packaged for transmission on a wireless
network. Each frame includes a source and destination MAC address, a
control field with protocol version, frame type, frame sequence number,
frame body (with the actual information to be transmitted) and frame
check sequence for error detection. A Frame is similar in concept to a
Packet, the difference being that a packet operates on the Network
layer (layer 3 in the OSI model) whereas a frame operates on the
Data-Link layer (layer 2 in the OSI model).

G

Gateway
A gateway is a network node that serves as an entrance to another
network. A gateway also often provides a proxy server and a firewall.
It is associated with both a router, which use headers and forwarding
tables to determine where packets are sent, and a switch or bridge,
which provides the actual path for the packet in and out of the
gateway.

Before a host on a LAN can access the Internet, it needs to know the address of its default gateway.


H

HTML
The Hyper**** Markup Language (HTML) defines the structure of a
******** on the World Wide Web. It uses tags and attributes to hint
about a layout for the ********.

An HTML ******** starts with an tag and ends with a
tag. A properly formatted ******** also contains a
... section, which contains the ****data to
define the ********, and a ... section,
which contains its *******. Its markup is derived from the Standard
Generalized Markup Language (SGML), which is defined in ISO 8879:1986.

HTML ********s are sent from server to browser via HTTP. Also see XML.

HTTP
The Hyper**** Transfer Protocol (HTTP) defines how messages are
formatted and transmitted on the World Wide Web. An HTTP message
consists of a URL and a command (GET, HEAD, POST, etc.), a request
followed by a response.



continue . . .

I

IAPP
The Inter Access Point Protocol (IAPP) is an IEEE standard (802.11f)
that defines communication between the access points in a "distribution
system". This includes the exchange of information about mobile
stations and the maintenance of bridge forwarding tables, plus securing
the communications between access points.

IBSS
An independent basic service set (IBSS) is an Ad hoc Mode Wireless
Networking Framework in which stations communicate directly with each
other.

IEEE
The Institute of Electrical and Electronic Engineers (IEEE) is an
international standards body that develops and establishes industry
standards for a broad range of technologies, including the 802 family
of networking and wireless standards. (See 802, 802.1x, 802.11,
802.11a, 802.11b, 802.11e, 802.11f, 802.11g, and 802.11i.)

For more information about IEEE task groups and standards, see http://standards.ieee.org/.

Infrastructure Mode
Infrastructure Mode is a Wireless Networking Framework in which
wireless stations communicate with each other by first going through an
Access Point. In this mode, the wireless stations can communicate with
each other or can communicate with hosts on a wired network. The access
point is connected to a wired network and supports a set of wireless
stations.

An infrastructure mode framework can be provided by a single access point (BSS) or a number of access points (ESS).

Intrusion Detection
The Intrusion Detection System (IDS) inspects all inbound network
activity and reports suspicious patterns that may indicate a network or
system attack from someone attempting to break into the system. It
reports access attempts using unsupported or known insecure protocols.

IP
The Internet Protocol (IP) specifies the format of packets, also called
datagrams, and the addressing scheme. IP is a connectionless,
best-effort packet switching protocol. It provides packet routing,
fragmentation and re-assembly. It is combined with higher-level
protocols, such as TCP or UDP, to establish the virtual connection
between destination and source.

The current version of IP is IPv4. A new version, called IPv6 or IPng,
is under development. IPv6 is an attempt to solve the shortage of IP
addresses.

IP Address
Systems are defined by their IP address, a four-byte (octet) number
uniquely defining each host on the Internet. It is usually shown in
form 192.168.2.254. This is called dotted-decimal notation.

An IP address is partitioned into two portions: the network prefix and
a host number on that network. A Subnet Mask is used to define the
portions. There are two special host numbers:

The Network Address consists of a host number that is all zeroes (for example, 192.168.2.0).
The Broadcast Address consists of a host number that is all ones (for example, 192.168.2.255).
There are a finite number of IP addresses that can exist. Therefore, a
local area network typically uses one of the IANA-designated address
ranges for use in private networks. These address ranges are:

10.0.0.0 to 10.255.255.255
172.16.0.0 to 172.31.255.255
192.168.0.0 to 192.168.255.255

A Dynamic IP Address is an IP address that is automatically assigned to
a host by a DHCP server or similar mechanism. It is called dynamic
because you may be assigned a different IP address each time you
establish a connection.

A Static IP Address is an IP address that is hard-wired for a specific
host. A static address is usually required for any host that is running
a server, for example, a Web server.

IPSec
IP Security (IPSec) is a set of protocols to support the secure
exchange of packets at the IP layer. It uses shared public keys. There
are two encryption modes: Transport and Tunnel.

Transport mode encrypts only the data portion (payload) of each packet, but leaves the headers untouched.
The more secure Tunnel mode encrypts both the header and the payload.
ISP
An Internet Service Provider (ISP) is a company that provides access to
the Internet to individuals and companies. It may provide related
services such as virtual hosting, network consulting, Web design, etc.


J

Jitter
Jitter is the difference between the latency (or delay) in packet
transmission from one node to another across a network. If packets are
not transmitted at a consistent rate (including Latency), QoS for some
types of data can be affected. For example, inconsistent transmission
rates can cause distortion in VoIP and streaming media. QoS is designed
to reduce jitter along with other factors that can impact network
performance.


L

Latency
Latency, also known as delay, is the amount of time it takes to
transmit a Packet from sender to receiver. Latency can occur when data
is transmitted from the access point to a client and vice versa. It can
also occur when data is transmitted from access point to the Internet
and vice versa. Latency is caused by fixed network factors such as the
time it takes to encode and decode a packet, and also by variable
network factors such as a busy or overloaded network. QoS features are
designed to minimize latency for high priority network traffic.

LAN
A Local Area Network (LAN) is a communications network covering a
limited area, for example, the computers in your home that you want to
network together or a couple of floors in a building. A LAN connects
multiple computers and other network devices such as storage and
printers. Ethernet is the most common technology implementing a LAN.

Wireless Ethernet (802.11) is another very popular LAN technology

LDAP
The Lightweight Directory Access Protocol (LDAP) is a protocol for
accessing on-line directory services. It is used to provide an
authentication mechanism. It is based on the X.500 standard, but less
complex.

Lease Time
The Lease Time specifies the period of time the DHCP Server gives its
clients an IP Address and other required information. When the lease
expires, the client must request a new lease. If the lease is set to a
short span, you can update your network information and propagate the
information provided to the clients in a timely manner.

LLC
The Logical Link Control (LLC) layer controls frame synchronization,
flow control, and error checking. It is a higher level protocol over
the PHY layer, working in conjunction with the MAC layer.


continue . . .

U

UDP
The User Datagram Protocol (UDP) is a transport layer protocol
providing simple but unreliable datagram services. It adds port address
information and a checksum to an IP packet.

UDP neither guarantees delivery nor does it require a connection. It is
lightweight and efficient. All error processing and retransmission must
be performed by the application program.

Unicast
A Unicast sends a message to a single, specified receiver. In wireless
networks, unicast usually refers to an interaction in which the access
point sends data traffic in the form of IEEE 802.1x Frames directly to
a single client station MAC address on the network.

Some wireless security modes distinguish between how unicast,
multicast, and broadcast frames are encrypted or whether they are
encrypted.


URL
A Uniform Resource Locator (URL) is a standard for specifying the
location of objects on the Internet, such as a file or a newsgroup.
URLs are used extensively in HTML ********s to specify the target of a
hyperlink which is often another HTML ******** (possibly stored on
another computer). The first part of the URL indicates what protocol to
use and the second part specifies the IP address or the domain name
where that resource is located.

For example, ftp://ftp.devicescape.com/downloads/myfile.tar.gz specifies a file that should be fetched using the FTP protocol; http://www.devicescape.com/index.html specifies a Web page that should be fetched using the HTTP protocol.


V

VLAN
A virtual LAN (VLAN) is a software-based, logical grouping of devices
on a network that allow them to act as if they are connected to a
single physical network, even though they may not be. The nodes in a
VLAN share resources and bandwidth, and are isolated on that network.
The Devicescape Universal Wireless Platform supports the configuration
of a wireless VLAN. This technology is leveraged on the access point
for the "virtual" guest network feature.

VPN
A Virtual Private Network (VPN) is a network that uses the Internet to
connect its nodes. It uses encryption and other mechanisms to ensure
that only authorized users can access its nodes and that data cannot be
intercepted.


W

WAN
A Wide Area Network (WAN) is a communications network that spans a
relatively large geographical area, extending over distances greater
than one kilometer. A WAN is often connected through public networks,
such as the telephone system. It can also be connected through leased
lines or satellites.

The Internet is essentially a very large WAN.

WDS
A Wireless Distribution System (WDS) allows the creation of a
completely wireless infrastructure. Typically, an Access Point is
connected to a wired LAN. WDS allows access points to be connected
wirelessly. The access points can function as wireless repeaters or
bridges.

WEP
Wired Equivalent Privacy (WEP) is a data encryption protocol for 802.11
wireless networks. All wireless stations and access points on the
network are configured with a static 64-bit (40-bit secret key + 24-bit
initialization vector (IV)) or 128-bit (104-bit secret key + 24-bit IV)
Shared Key for data encryption. It uses a RC4 stream cipher to encrypt
the frame body and CRC of each 802.11 frame before transmission.

Wi-Fi
A test and certification of interoperability for WLAN products based on
the IEEE 802.11 standard promoted by the Wi-Fi Alliance, a non-profit
trade organization.

WINS
The Windows Internet Naming Service (WINS) is a server process for
resolving Windows-based computer names to IP addresses. It provides
information that allows these systems to browse remote networks using
the Network Neighborhood.

Wireless Networking Framework
There are two ways of organizing a wireless network:

Stations communicate directly with one another in an Ad hoc Mode network, also known as an independent basic service set (IBSS).
Stations communicate through an Access Point in an Infrastructure Mode
network. A single access point creates an infrastructure basic service
set (BSS) whereas multiple access points are organized in an extended
service set (ESS).

WLAN
Wireless Local Area Network (WLAN) is a LAN that uses high-frequency
radio waves rather than wires to communicate between its nodes.

WMM
Wireless Multimedia (WMM) is a IEEE technology standard designed to
improve the quality of audio, video and multimedia applications on a
wireless network. Both access points and wireless clients (laptops,
consumer electronics products) can be WMM-enabled. WMM features are
based on is a subset of the WLAN IEEE 802.11e draft specification.
Wireless products that are built to the standard and pass a set of
quality tests can carry the "Wi-Fi certified for WMM" label to ensure
interoperability with other such products. For more information, see
the WMM page on the Wi-Fi Alliance Web site: http://www.wi-fi.org/OpenSection/wmm.asp.

WPA
Wi-Fi Protected Access (WPA) is a Wi-Fi Alliance version of the draft
IEEE 802.11i standard. It provides more sophisticated data encryption
than WEP and also provides user authentication. WPA includes TKIP and
802.1x mechanisms.

WPA2
WiFi Protected Access (WPA2) is an enhanced security standard,
described in IEEE 802.11i, that uses Advanced Encryption Standard (AES)
for data encryption.

The original WPA uses Temporal Key Integrity Protocol (TKIP) for data
encyrption. WPA2 is backwards-compatible with products that support the
original WPA.

WPA2, like the original WPA, supports an Enterprise and Personal
version. The Enterprise version requires use of IEEE 802.1x security
features and Extensible Authentication Protocol (EAP) authentication
with a RADIUS server.

The Personal version does not require IEEE 802.1x or EAP. It uses a
Pre-Shared Key (PSK) password to generate the keys needed for
authentication.

WRAP
Wireless Robust Authentication Protocol (WRAP) is an encryption method
for 802.11i that uses AES but another encryption mode (OCB) for
encryption and integrity.


X

XML
The Extensible Markup Language (XML) is a specification developed by
the W3C. XML is a simple, flexible **** format derived from Standard
Generalized Markup Language (SGML), which is defined in ISO 8879:1986,
designed especially for electronic publishing



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