All MAC address in MAC address table of Ethernet switch is associated with the VLAN.Each
VLAN will maintain its own logic address table. A MAC address that has been learned by
VLAN, still be unknown by other VLANs.
The MAC address of the Ethernet switch consists of the following information:
User MAC
Port
Port Method
VLAN
MAC address table
User MAC
：
MAC address information in table
Port
：
MAC address corresponding to the port information
Port Method
：
It marks dynamic address, static address or filtering address.
VLAN
：
VLAN belonging to MAC address
Ethernet switch MAC address table update and maintain by following two ways:
Dynamic address learning
Manual configuration address
Ethernet switches in the forwarded message through the message MAC address, and
message belonging to a VLAN ID information in the MAC address table to find the
corresponding forward output port, according to the search results to forward packets in
unicast, multicast or broadcast.
Unicast forwarding: Ethernet switch can check it MAC address and corresponding tables of
VLAN ID,and table output port is only one, and message output directly from a table item of
the corresponding port
Multicast forwarding: Ethernet switch can check message’s purpose MAC address and
tables that is correspond to VLAN ID, then forward message from multicast ports.
Broadcasting forwards: Ethernet switches received message of destination address to FFFF.
FFFF. FFFF or in the MAC address table, you can't find the corresponding item, the
message from under their VLAN all ports (in addition to receiving port) will be forwarded.
7.1.2.
Dynamic address learning
MAC address produced by automatic address learning process of Ethernet switch is called
dynamic address, only dynamic address will be deleted by aging mechanism of address
table.
Normally the MAC address table maintenance is conducted by means of dynamic address
learning, its working principle is as following:
In condition of MAC address of Ethernet switch is empty, UserA will communicate with UserB, UserA
first send message to Gigabit port of switch. Then Ethernet switch will learn MAC address of UserA to
MAC address table. As there is no source MAC address of UserB in the address table, then Ethernet
switch will send message in broadcasting method all ports except for UserA, and UserC can receive
message from UserA, that does not belong to it.