H3C WA2620X-AGNP, Web-Based Configuration Manual, Page: 102 / 447

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MAC address configuration
NOTE:
•
MAC address configurations related to interfaces apply only to Layer 2 Ethernet interfaces.
• This chapter covers only the management of static and dynamic MAC address entries, not multicast
MAC address entries.
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 table and
forwards it from port A.
NOTE:
Dynamically learned MAC addresses cannot overwrite static MAC address entries, but the latter can
overwrite the former.
When forwarding a frame, the device adopts 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 the destination address being all Fs, or no entry
matches the destination MAC address, the device broadcasts the frame to all the ports except the
receiving port.