Intermec 6710 - Manual (Page 27)

SECTION 2
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Features and Functional Overview
6710 Access Point User’s Guide 2-3
Bridges operate at the Media Access Control (MAC)
sublayer of the Data Link Layer (Layer 2) of the
International Organization for Standardization (ISO)
protocol model. Operating at the MAC layer allows bridges
to operate transparently to commonly used network
protocols such as TCP/IP, Novell SPX/IPX, NetBEUI, and
DECnet.
In wired LANs, bridges do the following:
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Segment traffic for better efficiency and performance.
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Extend the reach of LANs when cable length or node
limits have been reached.
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Translate between different LAN types such as IEEE
802.3 Ethernet and 802.5 Token Ring.
A LAN environment normally consists of a collection of
nodes or stations, each identified by a unique 48-bit
physical address (also called an IEEE address or MAC
address). Data is sent on the LAN as frames or packets
that contain the source address of the station sending the
frame, and the destination address of the recipient station.
A bridge has at least two ports, each connected to a
different LAN segment. Bridges learn which source
addresses are generating traffic on each of their ports. If
the bridge receives a frame with a destination address
corresponding to a source address it has seen on another
port, it forwards the frame to the port. If it receives a
frame where the source and destination addresses are on
the same port, it ignores (drops) the frame, since the
destination node receives the original transmission.
Generally, if a bridge receives a frame for an unknown
destination address on any one port, it floods the frame on
all other ports.