Layer 2 ports
correlate the MAC address on a packet with the Layer 2 port information for
that packet using the MAC address table. A MAC address table is built using the
MAC source addresses of the frames received. When a frame is received for a MAC
destination address not listed in the address table, the frame is flooded to
all LAN ports of the same VLAN with the exception of the port that received the
frame. When the destination station replies, the relevant MAC source addresses
and port IDs are added to the address table. Subsequent frames are forwarded to
a single LAN port without flooding all LAN ports.
You can configure MAC
addresses, which are called static MAC addresses, to statically point to
specified interfaces on the device. These static MAC addresses override any
dynamically learned MAC addresses on those interfaces. You cannot configure
broadcast or multicast addresses as static MAC addresses. The static MAC
entries are retained across reboots if you copy the static MAC addresses
configuration to the startup configuration by using the
copy running-config startup-config command.
The address table per
VEM can store up to 32,000 MAC entries. An aging timer triggers removal of
addresses from the table when they remain inactive for the default time of 300
seconds. The aging timer can be configured on a global basis but not per VLAN.
You can configure the
length of time an entry remains in the MAC address table, clear the table, and