ZyXEL Communications OLT2406, User Manual

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OLT2406 User’s Guide
385
C
HAPTER
47
MAC Table
47.1 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 OLT’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
OLT) or static (manually entered in the
Static MAC Forwarding screen).
47.1.1 What You Can Do
Use the MAC Table screen ( Section 47.2 on page 386 ) to check whether the MAC address is dynamic or
static.
47.1.2 What You Need to Know
The OLT uses the MAC table to determine how to forward frames. See the following figure.
1
The OLT examines a received frame and learns the port on which this source MAC address came.
2
The OLT checks to see if the frame's destination MAC address matches a source MAC address already
learned in the MAC table.
• If the OLT has already learned the port for this MAC address, then it forwards the frame to that port.
• If the OLT 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 OLT 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.