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MAC Address Table Overview Managing Source Learning
page 2-4 OmniSwitch 6600 Family Network Configuration Guide April 2006
MAC Address Table Overview
Source learning builds and maintains the MAC address table on each switch. New MAC address table
entries are created in one of two ways: they are dynamically learned or statically assigned. Dynamically
learned MAC addresses are those that are obtained by the switch when source learning examines data
packets and records the source address and the port and VLAN it was learned on.
Static MAC addresses are user defined addresses that are statically assigned to a port and VLAN using the
mac-address-table command or mac-address-table static-multicast command. See “Using Static MAC
Addresses” on page 2-4 or “Using Static Multicast MAC Addresses” on page 2-6 for more information.
Accessing MAC Address Table entries is useful for managing traffic flow and troubleshooting network
device connectivity problems. For example, if a workstation connected to the switch is unable to commu-
nicate with another workstation connected to the same switch, the MAC address table might show that one
of these devices was learned on a port that belonged to a different VLAN or the source MAC address of
one of the devices may not appear at all in the address table.
Using Static MAC Addresses
Static MAC addresses are configured using the mac-address-table command. These addresses direct
network traffic to a specific port and VLAN. They are particularly useful when dealing with silent network
devices. These types of devices do not send packets, so their source MAC address is never learned and
recorded in the MAC address table. Assigning a MAC address to the silent device’s port creates a record
in the MAC address table and ensures that packets destined for the silent device are forwarded out that
port.
When defining a static MAC address for a particular slot/port and VLAN, consider the following:
• Configuring static MAC addresses is only supported on non-mobile ports.
• The specified slot/port must already belong to the specified VLAN. Use the vlan port default
command to assign a port to a VLAN before you configure the static MAC address.
• Only traffic from other ports associated with the same VLAN is directed to the static MAC address
slot/port.
• There are three types of static MAC addresses available: permanent (default), reset, or timeout. The
type selected determines the status of the MAC address in the event of a switch reboot or when the
MAC address age exceeds the aging timer. These types are defined as follows:
Note that static MAC addresses configured with a reset or timeout status are not captured when a
snapshot of the switch’s running configuration is taken.
Status Definition
permanent MAC address remains in use even if MAC ages beyond the aging timer
value or the switch is rebooted.
reset MAC address is removed the next time the switch is rebooted.
timeout MAC address is removed when it ages beyond the aging timer value.