Chapter 11: Managing Mac Address Tables - Cisco 500 series Administration Manual

Managing MAC Address Tables
Cisco 500 Series Stackable Managed Switch Administration Guide
This section describe how to add MAC addresses to the system. It covers the
following topics:
• Configuring Static MAC Addresses
• Managing Dynamic MAC Addresses
• Defining Reserved MAC Addresses
Types of MAC Addresses
There are two types of MAC addresses—static and dynamic. Depending on their
type, MAC addresses are either stored in the Static Address table or in the
Dynamic Address table, along with VLAN and port information.
Static addresses are configured by the user, and therefore, they do not expire.
A new source MAC address that appears in a frame arriving at the switch is added
to the Dynamic Address table. This MAC address is retained for a configurable
period of time. If another frame with the same source MAC address does not
arrive at the switch before that time period expires, the MAC entry is aged
(deleted) from the table.
When a frame arrives at the switch, the switch searches for a corresponding/
matching destination MAC address entry in the static or dynamic table. If a match
is found, the frame is marked for egress on a the port specified in the table. If
frames are sent to a MAC address that is not found in the tables, they are
transmitted/broadcasted to all the ports on the relevant VLAN. Such frames are
referred to as unknown Unicast frames.
The switch supports a maximum of 8K static and dynamic MAC addresses.
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