ZyXEL Communications OMC-2301, User Manual

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OMC-2301 User’s Guide
137
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H A P T E R
17
MAC Table
This chapter introduces the MAC Table screen.
17.1 MAC Table Overview
The MAC Table screen (a MAC table is also known as a filtering database) shows how frames
are forwarded or filtered across the OMC’s ports. It shows what device MAC address,
belonging to what logical link and whether the MAC address is dynamic (learned by the
OMC) or static (manually entered in the
Static MAC Forwarding screen).
The OMC uses the MAC table to determine how to forward frames. See the following figure.
1 The OMC examines a received frame and learns the LLID on which this source MAC
address came.
2 If the MAC table is full and the OMC receives a frame with an unknown MAC address,
the frame is discarded.
3 The OMC checks to see if the frame's destination MAC address matches a source MAC
address already learned in the MAC table.
• If the OMC has already learned the LLID for this MAC address, then it forwards the
frame to that logical link.
• If the OMC has not already learned the LLID for this MAC address, and peer-to-peer
communication is enabled, then the frame is flooded to all PON ports. Too much port
flooding leads to network congestion.
If peer-to-peer communication is disabled, the frame is sent to the uplink ports.
• If the OMC has already learned the LLID for this MAC address, but the destination
LLID is the same as the source LLID, then it filters the frame.