Specifications

CHAPTER
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Cisco MWR 2941 Mobile Wireless Edge Router Release 3.5 Software Configuration Guide, Cisco IOS Release 15.1(3)MR
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Managing the MAC Address Table
The MAC address table contains address information that the switch uses to forward traffic between
ports. All MAC addresses in the address table are associated with one or more ports. The address table
includes these types of addresses:
• Dynamic address: a source MAC address that the switch learns and then ages when it is not in use.
• Static address: a manually entered unicast address that does not age and that is not lost when the
switch resets.
The address table lists the destination MAC address, the associated VLAN ID, and port number
associated with the address and the type (static or dynamic).
MAC address table management can be used with the STP, MSTP, and REP features. For more
information about configuring SPAN, see Chapter 9, “Configuring STP.” For more information about
configuring RSPAN, see Chapter 10, “Configuring MSTP.” For more information about configuring
REP, see Chapter 14, “Configuring Resilient Ethernet Protocol.”
The following sections describe how to manage the MAC address table:
• Disabling MAC Address Learning on an Interface or VLAN
• Displaying Address Table Entries
Disabling MAC Address Learning on an Interface or VLAN
By default, MAC address learning is enabled on all interfaces and VLANs on the router. You can control
MAC address learning on an interface or VLAN to manage the available MAC address table space by
controlling which interfaces or VLANs can learn MAC addresses. Before you disable MAC address
learning, be sure that you are familiar with the network topology and the router system configuration.
Disabling MAC address learning on an interface or VLAN could cause flooding in the network.
Follow these guidelines when disabling MAC address learning on an interface or VLAN:
• Use caution before disabling MAC address learning on an interface or VLAN with a configured
switch virtual interface (SVI). The switch then floods all IP packets in the Layer 2 domain.
• You can disable MAC address learning on a single VLAN ID from 1 to 4094 (for example, no mac
address-table learning vlan 223) or a range of VLAN IDs, separated by a hyphen or comma (for
example, no mac address-table learning vlan 1-10, 15).
• We recommend that you disable MAC address learning only in VLANs with two ports. If you
disable MAC address learning on a VLAN with more than two ports, every packet entering the
switch is flooded in that VLAN domain.