Mac address table configuration, Overview, How a mac address table entry is created – H3C Technologies H3C WX3000E Series Wireless Switches User Manual

Page 26: Mac address learning

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MAC address table configuration

This chapter includes these sections:

Overview

Configuring the MAC address table

Configuring static multicast MAC address entries

Displaying and maintaining MAC address tables

MAC address table configuration example

NOTE:

The term "switch" or "device" in this chapter refers to the switching engine on a WX3000E wireless
switch.

The WX3000E series comprises WX3024E and WX3010E wireless switches.

The port numbers in this chapter are for illustration only.

The port-related MAC address table configurations are supported on only Layer 2 ports, such as Layer
2 Ethernet ports and Layer 2 aggregate interfaces.

Overview

An Ethernet device uses a MAC address table for forwarding frames through unicast instead of

broadcast. This table describes from which port a MAC address (or host) can be reached. When
forwarding a frame, the device first looks up the MAC address of the frame in the MAC address table for

a match. If an entry is found, the device forwards the frame out of the outgoing port in the entry. If no

entry is found, the device broadcasts the frame out of all but the incoming port.

How a MAC address table entry is created

The entries in the MAC address table come from two sources: automatically learned by the device and

manually added by the administrator.

MAC address learning

The device can automatically populate its MAC address table by learning the source MAC addresses of

incoming frames on each port.
When a frame arrives at a port, Port A for example, the device performs the following tasks:

1.

Checks the source MAC address (MAC-SOURCE for example) of the frame.

2.

Looks up the source MAC address in the MAC address table.

{

If an entry is found, the device updates the entry.

{

If no entry is found, the device adds an entry for MAC-SOURCE and Port A.

3.

After learning this source MAC address, when the device receives a frame destined for
MAC-SOURCE, the device finds the MAC-SOURCE entry in the MAC address table and forwards

the frame out Port A.

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