Chapter 30 Mac Table; Introduction To Mac Table; Figure 30-1 Mac Table Flowchart - ZyXEL Communications Dimension ES-4024 User Manual

30.1 Introduction to MAC Table

The MAC Table screen (a MAC table is also known as a filtering database) 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 the Static MAC Forwarding screen).
The switch uses the MAC table 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 MAC table.
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.
No
Forward to all ports
except the incoming one.
MAC Table
Is destination
MAC address in
the MAC table?
No
Filter this frame.

Figure 30-1 MAC Table Flowchart

Dimension ES-4024 Ethernet Switch
Chapter 30
This chapter introduces the MAC Table screen.
Yes
Is outgoing port
different from
Forward to outgoing port.
MAC Table
Yes
30-1