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360
CHAPTER 44
MAC Table
44.1 MAC Table Overview
This chapter introduces the MAC Table screen.
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).
44.1.1 What You Can Do
Use the MAC Table screen (Section 44.2 on page 361) to check whether the MAC address is
dynamic or static.
44.1.2 What You Need to Know
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.
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