116
HomePortal 3801HGV Gateway User Guide Glossary
SYN Flood A method that the user of a hostile client program can use to conduct a denial-of-
service (DOS) attack on a computer server. The hostile client repeatedly sends SYN
(synchronization) packets to every port on the server, using fake IP addresses.
TCP/IP (Transmission Control
Protocol/Internet Protocol)
A method of packet-switched data transmission used on the Internet. The protocol
specifies the manner in which a signal is divided into parts, as well as the manner in
which “address” information is added to each packet to ensure that it reaches its
destination and can be reassembled into the original message.
UDP (User Datagram Protocol) A TCP/IP protocol describing how data packets reach application programs within a
destination computer.
VPI (Virtual Path Identifier) Identifier contained in the ATM cell header to designate the virtual path on the
physical ATM link.
VCI (Virtual Channel Identifier) Identifier contained in the ATM cell header to designate the virtual channel on the
physical ATM link.
Wireless Transmission of data over radio waves rather than wiring.
Wireless Channel The 2Wire gateway supports up to 13 wireless channels (based on country
restrictions).
For example, the United States and Canada support channels 1 to 11; Europe and
Australia support channels 1 to 13.
In an 802.1b or 802.11g wireless network, data is transmitted at 2.5GHz. Wireless
nodes communicate with each other using radio frequency signals in the band
between 2.4GHz and 2.5GHz. Neighboring channels are 5 MHz apart; however, due
to the spread spectrum effect of the signals, a node sending signals using a particular
channel will use frequency spectrum 12.5HHz above and below the center channel
frequency. As a result, two separate wireless networks using neighboring channels
(for example, channels 1 and 2) in the same general vicinity will interfere with each
other. Applying two channels that allow the maximum channel separation (such as
channels 1 and 6, or channels 6 and 11) will provide a noticeable performance
increase over networks with minimal channel separation.
The radio frequency channels used in 802.11b/g networks are shown in the following
table:
The preferred channel separation between the channels in neighboring wireless
networks is 25 MHz (5 channels). This means that you can apply up to three different
channels within your wireless network. There are only 11 usable wireless channels in
the United States. It is recommended that you start using channel 1 and expand to
channel 6 (and 11 when necessary), as these three channels do not overlap.
Term Description
Channel Frequency
Channel 1 2399.5 MHz-2424.5 MHz
Channel 2 2404.5 MHz-2429.5 MHz
Channel 3 2409.5 MHz - 2434.5 MHz
Channel 4 2414.5 MHz - 2439.5 MHz
Channel 5 2419.5 MHz - 2444.5 MHz
Channel 6 2424.5 MHz - 2449.5 MHz
Channel 7 2429.5 MHz - 2454.5 MHz
Channel 8 2434.5 MHz - 2459.5 MHz
Channel 9 2439.5 MHz - 2464.5 MHz
Channel 10 2444.5 MHz - 2469.5 MHz
Channel 11 2449.5 MHz - 2474.5 MHz
Channel 12 2454.5 MHz - 2479.5 MHz
Channel 13 2459.5 MHz - 2484.5 MHz