Cisco CCNA Packet Tracer Ultimate labs: MAC Address Learning and Flooding (Part 1)

Packet Tracer file (PT Version 7.1): https://bit.ly/2vFzGUU Get the Packet Tracer course for only $10 by clicking here: https://goo.gl/vikgKN Get my ICND1 and ICND2 courses for $10 here: https://goo.gl/XR1xm9 (you will get ICND2 as a free bonus when you buy the ICND1 course).

For lots more content, visit http://www.davidbombal.com - learn about GNS3, CCNA, Packet Tracer, Python, Ansible and much, much more.

#CCNA #PacketTracer #CCENT

The MAC address table contains address information that the switch uses to forward traffic between ports. All MAC addresses in the address table are associated with one or more ports. The address table includes these types of addresses:

•Dynamic address: a source MAC address that the switch learns and then ages when it is not in use.

•Static address: a manually entered unicast address that does not age and that is not lost when the switch resets.

The address table lists the destination MAC address, the associated VLAN ID, and port number associated with the address and the type (static or dynamic).

By default, MAC address learning is enabled on all interfaces and VLANs on the router. You can control MAC address learning on an interface or VLAN to manage the available MAC address table space by controlling which interfaces or VLANs can learn MAC addresses. Before you disable MAC address learning, be sure that you are familiar with the network topology and the router system configuration. Disabling MAC address learning on an interface or VLAN could cause flooding in the network.

Transcription:

In this video, I’m going to discuss how MAC address tables are populated on switches. I find that there’s often confusion about how MAC address tables work and how frames are flooded in layer 2 switches.

In this example, I’ve got a layer 2 switch. In other words I haven’t configured any VLANs. This switch is essentially doesn’t have any configuration apart from the default configuration.

When a switch first boots up, it doesn’t know about any MAC addresses in the network, unless you’ve statically configured them. To simulate that, I’m going to power cycle the devices in packet tracer and I’ll connect it to the console of the switch.

So essentially, this switch doesn’t know about the MAC addresses of the PCs in the topology when the switch first boots up.

so show mac address-table Notice the MAC address table is empty. The switch doesn’t know the MAC addresses of these 4 PCs. The only way the switch is going to learn the MAC addresses of these devices is if they send traffic into the network.

Now in the real world, operating systems such as Windows, broadcast packets when they boot up. So switches will learn the MAC addresses of Windows devices when they first start up.

In this exa ... https://www.youtube.com/watch?v=wKtA31whDSQ