dynamically builds the address table by using the MAC source address of the
frames received. When the device receives a frame for a MAC destination address
not listed in its address table, it floods the frame to all LAN ports of the
same VLAN except the port that received the frame. When the destination station
replies, the device adds its relevant MAC source address and port ID to the
address table. The device then forwards subsequent frames 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 addresses as static MAC addresses. Beginning with Cisco NX-OS Release
5.2(1), multicast MAC addresses can be configured as static MAC addresses. For
further information, see the “Configuring IGMP Snooping” of the
Cisco Nexus 7000 Series NX-OS Multicast Routing Configuration
Guide. The static MAC entries are retained across a reboot of the
Beginning with Cisco
NX-OS Release 4.1(5), you must manually configure identical static MAC
addresses on both devices connected by a virtual port channel (vPC) peer link.
The MAC address table display is enhanced to display information on MAC
addresses when you are using vPCs.
7000 Series NX-OS Interfaces Configuration Guide for information about
The address table
can store a number of MAC address entries depending on the hardware I/O module.
The device uses an aging mechanism, defined by a configurable aging timer, so
if an address remains inactive for a specified number of seconds, it is removed
from the address table.
7000 Series NX-OS Security Command Reference for information on MAC port