1-1 
1  MAC Address Table Management 
When configuring MAC address table management, go to these sections for information you are 
interested in: 
z  Overview 
z  MAC Address Table Management 
z  Displaying MAC Address Table Information 
z  Configuration Example 
 
 
This chapter describes the management of static, dynamic, and blackhole MAC address entries. For 
information about the management of multicast MAC address entries, refer to Multicast Operation. 
 
Overview 
Introduction to MAC Address Table 
An Ethernet switch is mainly used to forward packets at the data link layer, that is, transmit the packets 
to the corresponding ports according to the destination MAC address of the packets. To forward packets 
quickly, a switch maintains a MAC address table, which is a Layer 2 address table recording the MAC 
address-to-forwarding port association. Each entry in a MAC address table contains the following fields: 
z  Destination MAC address 
z  ID of the VLAN which a port belongs to 
z  Forwarding egress port number on the local switch 
When forwarding a packet, an Ethernet switch adopts one of the two forwarding methods based upon 
the MAC address table entries. 
z  Unicast forwarding: If the destination MAC address carried in the packet is included in a MAC 
address table entry, the switch forwards the packet through the forwarding egress port in the entry. 
z  Broadcast forwarding: If the destination MAC address carried in the packet is not included in the 
MAC address table, tthe switch broadcasts the packet to all ports except the one that originally 
received the packet.  
Introduction to MAC Address Learning 
MAC address table entries can be updated and maintained through the following two ways: 
z  Manual configuration 
z  MAC address learning