GS1900 Series User’s Guide 64
CHAPTER 9
Monitor: MAC Table
9.1 Overview
This section provides information for MAC Table in Monitor.
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. When a device (which may belong to a VLAN group)
sends a packet which is forwarded to a port on the Switch, the MAC address of the device is shown
on the Switch’s MAC Table. It also shows 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 from 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.
Figure 46 MAC Table Flowchart
This link takes you to a screen where you can view the MAC address and VLAN ID of a device attach
to a port. You can also view what kind of MAC address it is.
