H3C Technologies H3C S3600 Series Switches - Manual (Page 235)

1-3
2) After learning the MAC address of User A, the switch starts to forward the packet. Because there is
no MAC address and port information of User B in the existing MAC address table, the switch
forwards the packet to all ports except Ethernet 1/0/1 to ensure that User B can receive the packet.
Figure 1-3 MAC address learning diagram (2)
3) Because the switch 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 Ethernet 1/0/4, the switch records the association between the MAC
address of User B and the corresponding port to the MAC address table of the switch.
Figure 1-4 MAC address learning diagram (3)
4) At this time, the MAC address table of the switch includes two forwarding entries shown in Figure
1-5 . When forwarding the response packet, the switch unicasts the packet instead of broadcasting
it to User A through Ethernet 1/0/1, because MAC-A is already in the MAC address table.
Figure 1-5 MAC address table entries of the switch (2)