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Reference Manual for the 108 Mbps Wireless Firewall Router WGT624 v3
Glossary
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IP (Internet Protocol) address
A 32-bit number that identifies each sender or receiver of information that is sent across the Internet. An IP
address has two parts: an identifier of a particular network on the Internet and an identifier of the particular
device (which can be a server or a workstation) within that network.
ISO Network Model
A network model developed by the International Standards Organization (ISO) that consists of seven
different levels, or layers. By standardizing these layers, and the interfaces in between, different portions of
a given protocol can be modified or changed as technologies advance or systems requirements are altered.
The seven layers are:
Physical
Data Link
Network
Transport
Session
Presentation
Application
The IEEE 802.11 Standard encompasses the physical layer (PHY) and the lower portion of the data link
layer. The lower portion of the data link layer is often referred to as the Medium Access Controller (MAC)
sublayer.
MAC (Media Access Control)
Every wireless 802.11 device has its own specific MAC address hard-coded into it. This unique identifier
can be used to provide security for wireless networks. When a network uses a MAC table, only the 802.11
radios that have had their MAC addresses added to that network's MAC table will be able to get onto the
network.
Mesh Networks
Also called mesh topology, mesh is a network topology in which devices are connected with many
redundant interconnections between network nodes. In a full mesh topology every node has a connection to
every other node in the network. Mesh networks may be wired or wireless.
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In a wireless mesh example, each of the spheres below represent a mesh router. Corporate servers and
printers may be shared by attaching to each mesh router. For wireless access to the mesh, an access point
must be attached to any one of the mesh routers.
Multiple Input Multiple Output (MIMO)
MIMO refers to radio links with multiple antennas at the transmitter and the receiver side to improve the
performance of the wireless link.
NAT (Network Address Translation)
A network capability that enables a houseful of computers to dynamically share a single incoming IP
address from a dial-up, cable or xDSL connection. NAT takes the single incoming IP address and creates
new IP address for each client computer on the network.
Network name
Identifies the wireless network for all the shared components. During the installation process for most
wireless networks, you need to enter the network name or SSID. Different network names are used when
setting up your individual computer, wired network or workgroup.
NIC (Network Interface Card)
A type of PC adapter card that either works without wires (Wi-Fi) or attaches to a network cable to provide
two-way communication between the computer and network devices such as a hub or switch. Most office
wired NICs operate at 10 Mbps (Ethernet), 100 Mbps (Fast Ethernet) or 10/100 Mbps dual speed.
High-speed Gigabit and 10 Gigabit NIC cards are also available. See PC Card.
PC card (also called PCMCIA)
A removable, credit-card-sized memory or I/O (input/output) device that fits into a Type 2 PCMCIA
standard slot, PC Cards are used primarily in PCs, portable computers, PDAs and laptops. PC Card
peripherals include Wi-Fi cards, memory cards, modems, NICs, hard drives, etc.
PCI adapter
A high-performance I/O computer bus used internally on most computers. Other bus types include ISA and
AGP. PCIs and other computer buses enable the addition of internal cards that provide services and features
not supported by the motherboard or other connectors.
Peer-to-peer network (also called Ad-Hoc in WLANs)
A wireless or wired computer network that has no server or central hub or router. All the networked PCs are
equally able to act as a network server or client, and each client computer can talk to all the other wireless
computers without having to go through an access point or hub. However, since there is no central base
station to monitor traffic or provide Internet access, the various signals can collide with each other, reducing
overall performance.
PHY
The lowest layer within the OSI Network Model. It deals primarily with transmission of the raw bit stream
over the PHYsical transport medium. In the case of wireless LANs, the transport medium is free space. The
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PHY defines parameters such as data rates, modulation method, signaling parameters, transmitter/receiver
synchronization, etc. Within an actual radio implementation, the PHY corresponds to the radio front end and
baseband signal processing sections.
Plug and Play
A computer system feature that provides for automatic configuration of add-ons and peripheral devices such
as wireless PC Cards, printers, scanners and multimedia devices.
Proxy server
Used in larger companies and organizations to improve network operations and security, a proxy server is
able to prevent direct communication between two or more networks. The proxy server forwards allowable
data requests to remote servers and/or responds to data requests directly from stored remote server data
Range
The distance away from your access point that your wireless network can reach. Most Wi-Fi systems will
provide a range of a hundred feet or more. Depending on the environment and the type of antenna used,
Wi-Fi signals can have a range of up to mile
Residential gateway
A wireless device that connects multiple PCs, peripherals and the Internet on a home network. Most Wi-Fi
residential gateways provide DHCP and NAT as well.
RJ-45
Standard connectors used in Ethernet networks. Even though they look very similar to standard RJ-11
telephone connectors, RJ-45 connectors can have up to eight wires, whereas telephone connectors have only
four.
Roaming
Moving seamlessly from one AP coverage area to another with your laptop or desktop with no loss in
connectivity.
Rogue Access Point
"Rogue AP" is a term used to describe an unauthorized access point that is connected on the main home or
corporate network or operating in a stand-alone mode (in a parking lot or in a neighbor's building). Rogue
APs, by definition, are not under the management of network administrators and do not conform to network
security policies and may present a severe security risk. Ideally, it is best to have some type of WLAN
system that does not allow rogue access points to easily be added to an existing WLAN.
Router
A device that forwards data packets from one local area network (LAN) or wide area network (WAN) to
another. Based on routing tables and routing protocols, routers can read the network address in each
transmitted frame and make a decision on how to send it via the most efficient route based on traffic load,
line costs, speed, bad connections, etc.
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Satellite broadband
A wireless high-speed Internet connection provided by satellites. Some satellite broadband connections are
two-way—up and down. Others are one-way, with the satellite providing a high-speed downlink and then
using a dial-up telephone connection or other land-based system for the uplink to the Internet.
Server
A computer that provides its resources to other computers and devices on a network. These include print
servers, Internet servers and data servers. A server can also be combined with a hub or router.
Site survey
The process whereby a wireless network installer inspects a location prior to putting in a wireless network.
Site surveys are used to identify the radio- and client-use properties of a facility so that access points can be
optimally placed.
SSID (also called ESSID)
A 32-character unique identifier attached to the header of packets sent over a WLAN that acts as a password
when a mobile device tries to connect to the BSS. (Also called ESSID.) The SSID differentiates one WLAN
from another, so all access points and all devices attempting to connect to a specific WLAN must use the
same SSID.
A device will not be permitted to join the BSS unless it can provide the unique SSID. Because an SSID can
be sniffed in plain text from a packet, it does not supply any security to the network. An SSID is also
referred to as a Network Name because essentially it is a name that identifies a wireless network.
SSL (Secure Sockets Layer)
Commonly used encryption scheme used by many online retail and banking sites to protect the financial
integrity of transactions. When an SSL session begins, the server sends its public key to the browser. The
browser then sends a randomly generated secret key back to the server in order to have a secret key
exchange for that session.
Subnetwork or Subnet
Found in larger networks, these smaller networks are used to simplify addressing between numerous
computers. Subnets connect to the central network through a router, hub or gateway. Each individual
wireless LAN will probably use the same subnet for all the local computers it talks to.
Switch
A type of hub that efficiently controls the way multiple devices use the same network so that each can
operate at optimal performance. A switch acts as a networks traffic cop: rather than transmitting all the
packets it receives to all ports as a hub does, a switch transmits packets to only the receiving port.
TCP (Transmission Control Protocol)
A protocol used along with the Internet Protocol (IP) to send data in the form of individual units (called
packets) between computers over the Internet. While IP takes care of handling the actual delivery of the
data, TCP takes care of keeping track of the packets that a message is divided into for efficient routing
through the Internet.
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For example, when a web page is downloaded from a web server, the TCP program layer in that server
divides the file into packets, numbers the packets, and then forwards them individually to the IP program
layer. Although each packet has the same destination IP address, it may get routed differently through the
network. At the other end, TCP reassembles the individual packets and waits until they have all arrived to
forward them as a single file.
TCP/IP
The underlying technology behind the Internet and communications between computers in a network. The
first part, TCP, is the transport part, which matches the size of the messages on either end and guarantees that
the correct message has been received. The IP part is the user's computer address on a network. Every
computer in a TCP/IP network has its own IP address that is either dynamically assigned at startup or
permanently assigned. All TCP/IP messages contain the address of the destination network as well as the
address of the destination station. This enables TCP/IP messages to be transmitted to multiple networks
(subnets) within an organization or worldwide.
TKIP
A security feature that is a WEP enhancement: Temporal Key Integrity Protocol and Message Integrity
Check (MIC) is a modification of WEP to defend against known attacks (WEP+ four patches for key
mixing, message integrity, rekeying, initialization vector protection)
USB (Universal Serial Bus)
A high-speed bidirectional serial connection between a PC and a peripheral that transmits data at the rate of
12 megabits per second. The new USB 2.0 specification provides a data rate of up to 480 Mbps, compared to
standard USB at only 12 Mbps. 1394, FireWire and iLink all provide a bandwidth of up to 400 Mbps.
VoIP (Voice over IP)
Voice transmission using Internet Protocol to create digital packets distributed over the Internet. VoIP can be
less expensive than voice transmission using standard analog packets over POTS (Plain Old Telephone
Service).
VPN (Virtual Private Network)
A type of technology designed to increase the security of information transferred over the Internet. VPN can
work with either wired or wireless networks, as well as with dial-up connections over POTS. VPN creates a
private encrypted tunnel from the end user's computer, through the local wireless network, through the
Internet, all the way to the corporate servers and database.
War Chalking
The act of making chalk marks on outdoor surfaces (walls, sidewalks, buildings, sign posts, trees) to indicate
the existence of an open wireless network connection, usually offering an Internet connection so that others
can benefit from the free wireless access. The open connections typically come from the access points of
wireless networks located within buildings to serve enterprises. The chalk symbols indicate the type of
access point that is available at that specific spot.
There are three basic designs that are currently used: a pair of back-to-back semicircles, which denotes an
open node; a closed circle, which denotes a closed node; a closed circle with a “W” inside, which denotes a

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