3Com WX3000 operation manual 1MAC address learning diagram

1)As shown in Figure 1-1, User A and User B are both in VLAN 1. When User A communicates with User B, the packet from User A needs to be transmitted to GigabitEthernet 1/0/1. At this time, the device records the source MAC address of the packet, that is, the address “MAC-A” of User A to the MAC address table of the switch, forming an entry shown in Figure 1-2.

Figure 1-1MAC address learning diagram (1)

Figure 1-2MAC address table entry of the switch (1)

MAC-address	Port	VLAN ID
MAC-A	GigabitEthernet1/0/1	1

2)After learning the MAC address of User A, the device starts to forward the packet. Because there is no MAC address and port information of User B in the existing MAC address table, the device forwards the packet to all ports except GigabitEthernet 1/0/1 to ensure that User B can receive the packet.

Figure 1-3MAC address learning diagram (2)

3)Because the device broadcasts the packet, both User B and User C can receive the packet. However, User C is not the destination device of the packet, and therefore does not process the packet. Normally, User B will respond to User A, as shown in Figure 1-4. When the response packet from User B is sent to GigabitEthernet 1/0/4, the device records the association between the MAC address of User B and the corresponding port to its MAC address table.

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