Types Of Mac Address Table Entries; Mac Address Table-Based Frame Forwarding; Configuring The Mac Address Table; Configuring Static, Dynamic, And Blackhole Mac Address Table Entries - HP A6600 Configuration Manual

Types of MAC address table entries

A MAC address table can contain the following types of entries:
Static entries, which are manually added and never age out.
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Dynamic entries, which can be manually added or dynamically learned and may age out.
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Blackhole entries, which are manually configured and never age out. Blackhole entries are
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configured for filtering out frames with specific MAC addresses. For example, to block all packets
destined for a specific user for security concerns, configure the MAC address of this user as a
blackhole MAC address entry.
To adapt to network changes and prevent inactive entries from occupying table space, an aging
mechanism is adopted for dynamic MAC address entries. Each time a dynamic MAC address entry is
learned or created, an aging time starts. If the entry has not updated when the aging timer expires, the
router deletes the entry. If the entry has updated before the aging timer expires, the aging timer restarts.
A static or blackhole MAC address entry can overwrite a dynamic MAC address entry, but not vice
versa.

MAC address table-based frame forwarding

When forwarding a frame, the router adopts the following forwarding modes based on the MAC address
table:
Unicast mode: If an entry is available for the destination MAC address, the router forwards the
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frame out the outgoing interface indicated by the MAC address table entry.
• Broadcast mode: If the router receives a frame with the destination address being all ones, or no
entry is available for the destination MAC address, the router broadcasts the frame to all interfaces
except the receiving interface.

Configuring the MAC address table

These configuration tasks are all optional and can be performed in any order.
Configuring static, dynamic, and blackhole MAC address table
entries
To fence off MAC address spoofing attacks and improve port security, manually add MAC address table
entries to bind ports with MAC addresses.
Also, configure blackhole MAC address entries to filter out packets with certain MAC addresses.
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