In this lesson, Ill demonstrate how a switch learns MAC addresses.

Let me show you an example of three computers connected to a switch.

Our switch has a MAC address table and it will learn where all the MAC addresses are in the network.

Let me show you an example of three computers connected to a switch: Theres a switch in the middle and we have 3 computers.

Our switch has a MAC address table and heres what will happen.

If the destination MAC address is known, it forwards it out of the correct interface (except the one it came from).

If th. Continue reading in our forum.

If the destination MAC address is known, it forwards it out of the correct interface.

If the destination MAC address is unknown, it is flooded on all ports (except the one where it came from).

If the destination MAC address is a broadcast, it is flooded on all ports (except the one it came from).

These MAC addresses are only used for traffic that is destined to or generated from the switch itself.

For traffic from one PC to another for example, these MAC addresses dont play any role.

After all, if it wants to send an IP packet with a destination IP address, it has to figure out what the layer two MAC address is.

For example, perhaps you just rebooted it and it wants to send syslog in.

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Addressing Information For A Switch To Build Its Mac Address Table