ADC WFX-3900-16 L11 User Manual page 160

Glossary December 22, 2005
Remote DC Power System (WFX-3100) – An optional proprietary product that provides distributed DC power to
multiple WFX-3900 units, eliminating the need to run dedicated AC power to each unit and facilitating backup
power when connected via a UPS.
RSSI – (Received Signal Strength Indicator) A measure of the energy observed by an antenna when receiving a
signal.
S
SDMA – (Spatial Division Multiple Access) A wireless communications mode that optimizes the use of the radio
spectrum and minimizes cost by taking advantage of the directional properties of antennas. The antennas are
highly directional, allowing duplicate frequencies to be used for multiple zones.
SNMP – (Simple Network Management Protocol) A standard protocol that regulates network management over the
Internet.
SNTP – (Simple Network Time Protocol) A simplified version of NTP. SNTP can be used when the ultimate
performance of the full NTP implementation described in RFC 1305 is not needed or justified.
SSH – (Secure SHell) Developed by SSH Communications Security, Secure Shell is a program to log into another
computer over a network, to execute commands in a remote machine, and to move files from one machine to
another. It provides strong authentication and secure communications over insecure channels. SSH protects a
network from attacks, such as IP spoofing, IP source routing, and DNS spoofing. Attackers who has managed to
take over a network can only force SSH to disconnect—they cannot "play back" the traffic or hijack the connection
when encryption is enabled. When using SSH's slogin (instead of rlogin) the entire login session, including
transmission of password, is encrypted making it almost impossible for an outsider to collect passwords.
SSID – (Service Set IDentifier) Every wireless network or network subset (such as a BSS) has a unique identifier
called an SSID. Every device connected to that part of the network uses the same SSID to identify itself as part of
the family—when it wants to gain access to the network or verify the origin of a data packet it is sending over the
network. In short, it is the unique name shared among all devices in a WLAN.
subnet mask – A mask used to determine what subnet an IP address belongs to. An IP address has two
components: (1) the network address and (2) the host address. For example, consider the IP address
150.215.017.009. Assuming this is part of a Class B network, the first two numbers (150.215) represent the Class
B network address, and the second two numbers (017.009) identify a particular host on this network.
T
TKIP – (Temporal Key Integrity Protocol) Provides improved data encryption by scrambling the keys using a
hashing algorithm and, by adding an integrity-checking feature, ensures that the encryption keys haven't been
tampered with.
transmit power – The amount of power used by a radio transceiver to send the signal out. Transmit power is
generally measured in milliwatts, which you can convert to dBm.
V
VLAN – (Virtual LAN) A group of devices that communicate as a single network, even though they are physically
located on different LAN segments. Because VLANs are based on logical rather than physical connections, they
are extremely flexible. A device that is moved to another location can remain on the same VLAN without any
hardware reconfiguration.
VLAN tagging – (Virtual LAN tagging) Static port-based VLANs were originally the only way to segment a network
without using routing, but these port-based VLANs could only be implemented on a single switch (or switches)
cabled together. Routing was required to transfer traffic between unconnected switches. As an alternative to
routing, some vendors created proprietary schemes for sharing VLAN information across switches. These methods
would only operate on that vendor's equipment and were not an acceptable way to implement VLANs. With the
adoption of the 802.1Q standard, traffic can be confined to VLANs that exist on multiple switches from different
vendors. This interoperability and traffic containment across different switches is the result of a switch's ability to
use and recognize 802.1Q tag headers—called VLAN tagging. Switches that implement 802.1Q tagging add this
tag header to the frame directly after the destination and source MAC addresses.
GL-4 AIWS-UM-4003-01