Mac Table; Chapter 37 Mac Table; Mac Table Overview; What You Can Do - ZyXEL Communications GS1915 Series User Manual

37.1 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 ports and whether the MAC address is dynamic (learned by
the Switch) or static (manually entered in the Static MAC Forwarding screen).

37.1.1 What You Can Do

Use the MAC Table screen
static.

37.1.2 What You Need to Know

The Switch uses the MAC Table to determine how to forward frames. See the following figure.
The Switch examines a received frame and learns the port on which this source MAC address came.
1
The Switch checks to see if the frame's destination MAC address matches a source MAC address
2
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, then the Switch sends an ARP to request
the MAC address. The Switch then learns the port that replies with the MAC address.
• 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.
(Section 37.2 on page 295) to check whether the MAC address is dynamic or
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MAC Table

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