MAC address configuration
NOTE:
The MAC address table can contain only Layer 2 Ethernet ports.
This manual covers only the management of static and dynamic MAC address entries, not multicast MAC address entries.
An Ethernet device uses a MAC address table for forwarding frames through unicast instead of broadcast. This table describes from which port a MAC address (or host) can be reached. The entries in the MAC address table come from two sources: automatically learned by the device and manually added by the administrator. Static entries never age out, but dynamic entries, which are whether manually configured or dynamically learned, will age out.
The device can automatically populate its MAC address table by learning the source MAC addresses of incoming frames on each port.
When a frame arrives at a port, Port A for example, the device performs the following tasks: Table 46 Checks the source MAC address
Table 47 Looks up the source MAC address in the MAC address table. If an entry is found, the device updates the entry.
If no entry is found, the device adds an entry for
After learning the source MAC address, when the device receives a frame destined for
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 two forwarding modes based on the MAC address table:
∙Unicast mode: If an entry is available for the destination MAC address, the device forwards the frame out the outgoing interface indicated by the MAC address table entry.
∙Broadcast mode: If the device receives a frame with an
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