ZyXEL Communications OLT2406, User Manual

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Chapter 88 MAC Address
OLT2406 User’s Guide
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HAPTER
88
MAC Address
88.1 MAC Address Table Overview
The MAC Address table (a MAC table is also known as a filtering database) shows how frames are
forwarded or filtered across the OLT’s ports. When a device (which may belong to a VLAN group) sends
a packet which is forwarded to a port on the OLT, the MAC address of the device is shown on the OLT’s
MAC table. It also shows whether the MAC address is dynamic (learned by the OLT) or static (manually
entered by static MAC forwarding).
The OLT uses the MAC table to determine how to forward frames. See the following figure.
1
The OLT examines a received frame and learns the port from which this source MAC address came.
2
The OLT checks to see if the frame's destination MAC address matches a source MAC address already
learned in the MAC table.
• If the OLT has already learned the port for this MAC address, then it forwards the frame to that port.
• If the OLT has not already learned the port for this MAC address, then the frame is flooded to all ports.
Too much port flooding leads to network congestion.
• If the OLT has already learned the port for this MAC address, but the destination port is the same as
the port it came in on, then it filters the frame.
Figure 286 MAC Address Table Flowchart