Intermec MobileLAN 21 Series System Manual page 255

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Glossary
ARP (Address Resolution Protocol)
Address Resolution Protocol. The protocol used by TCP/IP networks to relate IP
addresses with the physical network addresses of network interfaces.
BFSK (Binary Frequency Shift Key)
A broadcasting method that lengthens the range but halves the throughput as compared
to the QFSK method. In access points using an OpenAir radio, the radio can be
configured so that it automatically switches to this method when the RF protocol
determines that throughput is degrading due to range. The transmit mode parameter
determines if BFSK will be used. The default setting for transmit mode is AUTO,
which allows this automatic switching to occur.
broadcast
A type of transmission in which a message sent from the host is received by many
devices on the system.
channel
The path for transmitting data from a device to the host computer. A port may contain
one or more logical channels. In 2.4 GHz RF networks, the channel refers to the
frequency hopping sequence the radio follows.
data link tunneling
Data link tunneling occurs when an access point encapsulates an Ethernet frame in a
data frame and forwards the frame to the next access point on the path to the final
destination. It is used to make mobility transparent to the underlying network or to
isolate the radio traffic from terminals on an Ethernet segment.
Data link tunneling occurs automatically when Ethernet bridging is enabled on the root
access point and disabled on all other access points. If there is no designated bridge for
the secondary LAN, Ethernet bridging is automatically disabled. An access point that
has Ethernet bridging disabled forwards a frame inbound on its Ethernet port using data
link tunneling. The root access point or a designated bridge uses data link tunneling to
forward frames outbound to access points on the same Ethernet segment.
Data link tunneling is mainly used on networks with switches and when the access
points are installed on different ports of the switches. A switch learns the access point's
IP address and port. However, as a wireless end device roams from one access point to
another, it will be on a different port of the switch, thus frames sent to the end device
from the host will be sent to the wrong port. Data link tunneling encapsulates all access
point frames and forwards the frames to the root access point and then to the host. Data
link tunneling is done through the access points' physical Ethernet ports.
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