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D -56 Psion Teklogix 9160 G2 Wireless Gateway User Manual
Appendix D: Glossary
Frame
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.
See also CSMA/CA protocol.
F
Frame
A Frame consists of a discrete portion of data along with some descriptive meta-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 .