H3C Technologies H3C WX3000 Series Unified Switches - Manual (Page 165)

21-4
Managing MAC Address Table
Aging of MAC address table
To fully utilize a MAC address table, which has a limited capacity, the device uses an aging mechanism
for updating the table. That is, the device starts an aging timer for an entry when dynamically creating
the entry, and removes the MAC address entry if no more packets with the MAC address recorded in the
entry are received within the aging time.
Aging timer only takes effect on dynamic MAC address entries.
Entries in a MAC address table
Entries in a MAC address table fall into the following categories according to their characteristics and
configuration methods:
z
Static MAC address entry: Also known as permanent MAC address entry. This type of MAC
address entries are added/removed manually and can not age out by themselves. Using static
MAC address entries can reduce broadcast packets remarkably and are suitable for networks
where network devices seldom change.
z
Dynamic MAC address entry: Dynamic MAC address entries age out after the configured aging
time. They are generated by the MAC address learning mechanism or configured manually.
z
Blackhole MAC address entry: Blackhole MAC address entries are configured manually. The
device discards the packets destined for or originated from the MAC addresses contained in
blackhole MAC address entries.
Table 21-1 lists the different types of MAC address entries and their characteristics.
Table 21-1 Characteristics of different types of MAC address entries
MAC address entry Configuration method Aging time
Reserved or not at reboot (if the
configuration is saved)
Static MAC address entry Manually configured Unavailable Yes
Dynamic MAC address
entry
Manually configured or
generated by MAC
address learning
mechanism
Available No
Blackhole MAC address
entry
Manually configured Unavailable Yes
Configuring MAC Address Table Management
Configuration Task List
Complete the following tasks to configure MAC address table management: