Chapter 28 Mac Table; Introduction To Mac Table; Figure 105 Mac Table Flowchart - ZyXEL Communications GS-3012F User Manual

GS-3012/GS-3012F User's Guide
This chapter introduces MAC Table.

28.1 Introduction to MAC Table

The MAC table shows how frames are forwarded or filtered across the switch's ports. It shows
what device MAC address, belonging to what VLAN group (if any) is forwarded to which
port(s) and whether the MAC address is dynamic (learned by the switch) or static (manually
entered in Static MAC Forwarding).
The switch uses the Filtering Database to determine how to forward frames. See the following
figure.
1 The switch examines a received frame and learns the port on which this source MAC
address came.
2 The switch checks to see if the frame's destination MAC address matches a source MAC
address already learned in the Filtering Database.
• If the switch has already learned the port for this MAC address, then it forwards the
frame to that port.
• If the switch 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 switch 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 105 MAC Table Flowchart

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Chapter 28 MAC Table