Chapter 14: Managing Mac Address Tables - Cisco SX350 Series Administration Manual

Managing MAC Address Tables
Cisco Sx350, SG350X, SG350XG, Sx550X & SG550XG Series Managed Switches, Firmware Release 2.2.5.x
This section describe how to add MAC addresses to the system. It covers the following topics:
• Static Addresses
• Dynamic Addresses
• Reserved 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 device 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 device before that
time period expires, the MAC entry is aged (deleted) from the table.
When a frame arrives at the device, the device 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 device supports a maximum of 8K static and dynamic MAC addresses.
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