HP V1910, Руководство пользователя

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172
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 (MAC-SOURCE for example) of the frame.
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 MAC-SOURCE and Port A.
After learning the source MAC address, when the device receives a frame destined for MAC-SOURCE, the
device finds the MAC-SOURCE entry in the MAC address table and forwards the frame out 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 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 all-ones destination address, or no entry is
available for the destination MAC address, the device broadcasts the frame to all the interfaces except
the receiving interface.