H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 175)

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Configuring MAC addresses
MAC address configurations related to interfaces apply only to Layer 2 Ethernet interfaces.
This chapter provides information about the management of static and dynamic MAC address entries. It
does not provide information about multicast MAC address entries.
Overview
A device maintains a MAC address table for frame forwarding. Each entry in this table indicates the
MAC address of a connected device, to which interface this device is connected and to which VLAN the
interface belongs. A MAC address table consists of two types of entries: static and dynamic. Static
entries are manually configured and never age out. Dynamic entries can be manually configured or
dynamically learned and will age out.
When a frame arrives at a port, Port A for example, the device performs the following tasks:
1. Checks the frame for the source MAC address (MAC-SOURCE for example).
2. Looks up the MAC address in the MAC address table.
If an entry is found, updates the entry.
If no entry is found, adds an entry for the MAC address and the receiving port (Port A) to the
MAC address table.
When receiving a frame destined for MAC-SOURCE, the device looks up the MAC address in the MAC
address table and forwards the frame from port A.
NOTE:
Dynamically learned MAC addresses cannot overwrite static MAC address entries, but the static MAC
address entries can overwrite dynamically learned MAC addresses.
When forwarding a frame, the device uses the following forwarding modes based on the MAC address
table:
• Unicast mode—If an entry matching the destination MAC address exists, the device forwards the
frame directly from the sending port recorded in the entry.
• Broadcast mode—If the device receives a frame with a destination address of all Fs, or no entry
matches the destination MAC address, the device broadcasts the frame to all the ports except the
receiving port.