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Reference Manual for the RangeMax Wireless Router WPN824
Glossary
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202-10072-01, March 2005
Access Point (AP)
A wireless LAN transceiver or "base station" that can connect a wired LAN to one or many wireless devices.
Access points can also bridge to each other.
There are various types of access points, also referred to as base stations, used in both wireless and wired
networks. These include bridges, hubs, switches, routers and gateways. The differences between them are
not always precise, because certain capabilities associated with one can also be added to another. For
example, a router can do bridging, and a hub may also be a switch. But they are all involved in making sure
data is transferred from one location to another.
A bridge connects devices that all use the same kind of protocol. A router can connect networks that use
differing protocols. It also reads the addresses included in the packets and routes them to the appropriate
computer station, working with any other routers in the network to choose the best path to send the packets
on. A wireless hub or access point adds a few capabilities such as roaming and provides a network
connection to a variety of clients, but it does not allocate bandwidth. A switch is a hub that has extra
intelligence: It can read the address of a packet and send it to the appropriate computer station. A wireless
gateway is an access point that provides additional capabilities such as NAT routing, DHCP, firewalls,
security, etc.
Ad-Hoc mode
A client setting that provides independent peer-to-peer connectivity in a wireless LAN. An alternative set-up
is one where PCs communicate with each other through an AP. See access point and Infrastructure mode.
Bandwidth
The amount of transmission capacity that is available on a network at any point in time. Available bandwidth
depends on several variables such as the rate of data transmission speed between networked devices,
network overhead, number of users, and the type of device used to connect PCs to a network. It is similar to
a pipeline in that capacity is determined by size: the wider the pipe, the more water can flow through it; the
more bandwidth a network provides, the more data can flow through it. Standard 802.11b provides a
bandwidth of 11 Mbps; 802.11a and 802.11g provide a bandwidth of 54 Mbps.
Bits per second (bps)
A measure of data transmission speed over communication lines based on the number of bits that can be sent
or received per second. Bits per second—bps—is often confused with bytes per second—Bps. While "bits"
is a measure of transmission speed, "bytes" is a measure of storage capability. 8 bits make a byte, so if a
wireless network is operating at a bandwidth of 11 megabits per second (11 Mbps or 11 Mbits/sec), it is
sending data at 1.375 megabytes per second (1.375 Mbps).
Bluetooth Wireless Technology
A technology specification for linking portable computers, personal digital assistants (PDAs) and mobile
phones for short-range transmission of voice and data across a global radio frequency band without the need
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Reference Manual for the RangeMax Wireless Router WPN824
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Glossary
202-10072-01, March 2005
for cables or wires. Bluetooth is a frequency-hopping technology in the 2.4 GHz frequency spectrum, with a
range of 30 feet and up to 11Mbps raw data throughput.
Bridge
A product that connects a local area network (LAN) to another local area network that uses the same
protocol (for example, wireless, Ethernet or token ring). Wireless bridges are commonly used to link
buildings in campuses.
Client or Client devices
Any computer connected to a network that requests services (files, print capability) from another member of
the network. Clients are end users. Wi-Fi client devices include PC Cards that slide into laptop computers,
mini-PCI modules embedded in laptop computers and mobile computing devices, as well as USB and PCI/
ISA bus Wi-Fi radios. Client devices usually communicate with hub devices like access points and
gateways.
Collision avoidance
A network node characteristic for proactively detecting that it can transmit a signal without risking a
collision, thereby ensuring a more reliable connection.
Crossover cable
A special cable used for networking two computers without the use of a hub. Crossover cables may also be
required for connecting a cable or DSL modem to a wireless gateway or access point. Instead of the signals
transferring in parallel paths from one set of plugs to another, the signals "crossover." If an eight-wire cable
was being used, for instance, the signal would start on pin one at one end of the cable and end up on pin
eight at the other end. They "cross-over" from one side to the other.
CSMA/CA (Carrier Sense Multiple Action/Collision Avoidance)
CSMA/CA is the principle medium access method employed by IEEE 802.11 WLANs. It is a "listen before
talk": method of minimizing (but not eliminating) collisions caused by simultaneous transmission by
multiple radios. IEEE 802.11 states collision avoidance method rather than collision detection must be used,
because the standard employs half duplex radios—radios capable of transmission or reception—but not both
simultaneously.
Unlike conventional wired Ethernet nodes, a WLAN station cannot detect a collision while transmitting. If a
collision occurs, the transmitting station will not receive an ACKnowledge packet from the intended receive
station. For this reason, ACK packets have a higher priority than all other network traffic. After completion
of a data transmission, the receive station will begin transmission of the ACK packet before any other node
can begin transmitting a new data packet. All other stations must wait a longer pseudo randomized period of
time before transmitting. If an ACK packet is not received, the transmitting station will wait for a subsequent
opportunity to retry transmission
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Reference Manual for the RangeMax Wireless Router WPN824
Glossary
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CSMA/CD (Carrier Sense Multiple Action/Collision Detection)
A method of managing traffic and reducing noise on an Ethernet network. A network device transmits data
after detecting that a channel is available. However, if two devices transmit data simultaneously, the sending
devices detect a collision and retransmit after a random time delay.
DHCP (Dynamic Host Configuration Protocol)
A utility that enables a server to dynamically assign IP addresses from a predefined list and limit their time
of use so that they can be reassigned. Without DHCP, an IT Manager would have to manually enter in all the
IP addresses of all the computers on the network. When DHCP is used, whenever a computer logs onto the
network, it automatically gets an IP address assigned to it.
Diversity: antenna
A type of antenna system that uses two antennas to maximize reception and transmission quality and reduce
interference
DNS (Domain Name System)
A program that translates URLs to IP addresses by accessing a database maintained on a collection of
Internet servers. The program works behind the scenes to facilitate surfing the Web with alpha versus
numeric addresses. A DNS server converts a name like mywebsite.com to a series of numbers like
107.22.55.26. Every website has its own specific IP address on the Internet.
Encryption Key
An alphanumeric (letters and/or numbers) series that enables data to be encrypted and then decrypted so it
can be safely shared among members of a network. WEP uses an encryption key that automatically encrypts
outgoing wireless data. On the receiving side, the same encryption key enables the computer to
automatically decrypt the information so it can be read.
Enhanced Data Encryption through TKIP
To improve data encryption, Wi-Fi Protected Access utilizes its Temporal Key Integrity Protocol (TKIP).
TKIP provides important data encryption enhancements including a per-packet key mixing function, a
message integrity check (MIC) named Michael, an extended initialization vector (IV) with sequencing rules,
and a re-keying mechanism. Through these enhancements, TKIP addresses all WEP known vulnerabilities.
Enterprise-level User Authentication via 802.1x and EAP
WEP has almost no user authentication mechanism. To strengthen user authentication, Wi-Fi Protected
Access implements 802.1x and the Extensible Authentication Protocol (EAP). Together, these
implementations provide a framework for strong user authentication. This framework utilizes a central
authentication server, such as RADIUS, to authenticate each user on the network before they join it, and also
employs "mutual authentication" so that the wireless user doesn’t accidentally join a rogue network that
might steal its network credentials.
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Glossary
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ESSID (more commonly referred to as SSID – Short Set Identifier)
The identifying name of an 802.11 wireless network. When you specify your correct ESSID in your client
setup you ensure that you connect to your wireless network rather than another network in range. (See
SSID.) The ESSID can be called by different terms, such as Network Name, Preferred Network, SSID or
Wireless LAN Service Area.
Ethernet
International standard networking technology for wired implementations. Basic 10BaseT networks offer a
bandwidth of about 10 Mbps. Fast Ethernet (100 Mbps) and Gigabit Ethernet (1000 Mbps) are becoming
popular.
Firewall
A system that secures a network and prevents access by unauthorized users. Firewalls can be software,
hardware or a combination of both. Firewalls can prevent unrestricted access into a network, as well as
restrict data from flowing out of a network.
Gateway
In the wireless world, a gateway is an access point with additional software capabilities such as providing
NAT and DHCP. Gateways may also provide VPN support, roaming, firewalls, various levels of security,
etc.
Hot Spot (also referred to as Public Access Location)
A place where you can access Wi-Fi service. This can be for free or for a fee. HotSpots can be inside a coffee
shop, airport lounge, train station, convention center, hotel or any other public meeting area. Corporations
and campuses are also implementing HotSpots to provide wireless Internet access to their visitors and
guests. In some parts of the world, HotSpots are known as CoolSpots.
Hub
A multiport device used to connect PCs to a network via Ethernet cabling or via Wi-Fi. Wired hubs can have
numerous ports and can transmit data at speeds ranging from 10 Mbps to multigigabyte speeds per second.
A hub transmits packets it receives to all the connected ports. A small wired hub may only connect 4
computers; a large hub can connect 48 or more. Wireless hubs can connect hundreds.
HZ (‘hertz”)
The international unit for measuring frequency, equivalent to the older unit of cycles per second. One
megahertz (MHz) is one million hertz. One gigahertz (GHz) is one billion hertz. The standard US electrical
power frequency is 60 Hz, the AM broadcast radio frequency band is 535—1605 kHz, the FM broadcast
radio frequency band is 88—108 MHz, and wireless 802.11b LANs operate at 2.4 GHz.
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Reference Manual for the RangeMax Wireless Router WPN824
Glossary
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202-10072-01, March 2005
IEEE (Institute of Electrical and Electronics Engineers)
A membership organization (
www.ieee.org
) that includes engineers, scientists and students in electronics
and allied fields. It has more than 300,000 members and is involved with setting standards for computers and
communications.
IEEE 802.11
A set of specifications for LANs from The Institute of Electrical and Electronics Engineers (IEEE). Most
wired networks conform to 802.3, the specification for CSMA/CD based Ethernet networks or 802.5, the
specification for token ring networks. 802.11 defines the standard for wireless LANs encompassing three
incompatible (non-interoperable) technologies: Frequency Hopping Spread Spectrum (FHSS), Direct
Sequence Spread Spectrum (DSSS) and Infrared. WECA’s (Wireless Ethernet Compatibility Alliance – now
Wi-Fi Alliance) focus is on 802.11b, an 11 Mbps high-rate DSSS standard for wireless networks.
Infrastructure mode
A client setting providing connectivity to an access point (AP). As compared to Ad-Hoc mode, whereby PCs
communicate directly with each other, clients set in Infrastructure Mode all pass data through a central AP.
The AP not only mediates wireless network traffic in the immediate neighborhood, but also provides
communication with the wired network. See Ad-Hoc and AP.
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.

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