Consistent Mac Address Tables On The Supervisor And On The Modules; Layer 3 Static Mac Addresses - Cisco Nexus 7000 Series Configuration Manual

Configuring Layer 2 Switching
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 device.
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.
See the Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide for information about vPCs.
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.
See the Cisco Nexus 7000 Series NX-OS Security Command Reference for information on MAC port security.

Consistent MAC Address Tables on the Supervisor and on the Modules

Optimally, all the MAC address tables on each module exactly match the MAC address table on the supervisor.
Beginning with Cisco NX-OS 4.1(2), when you enter the show forwarding consistency l2 command, the
device displays discrepant, missing, and extra MAC address entries.

Layer 3 Static MAC Addresses

Beginning with Release 4.2, you can configure a static MAC address for all Layer 3 interfaces. The default
MAC address for the Layer 3 interfaces is the VDC MAC address.
You can configure a static MAC address for the following Layer 3 interfaces:
• Layer 3 interfaces
• Layer 3 subinterfaces
• Layer 3 port channels
• VLAN network interface
Note You cannot configure static MAC address on tunnel interfaces.
See the Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide for information on configuring Layer
3 interfaces.
Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.x
Layer 2 Ethernet Switching Overview
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