dynamically allow the switch to learn mac addresses of pcs on vlan

Now we will move on to the question of how the devices get the destination MAC addresses to begin this process in a word, ARP. An important detail to remember is that the MAC address table timeout is typically short (Cisco's default is five minutes), so an entry is left in the table itself only for that specified amount of time before the timeout expires and the entry is removed from the table. This process repeats as devices continue to send traffic to each other. Total Mac Addresses for this criterion: 2

Listing 1 shows what the MAC address table would look like at this point. It would then perform a lookup of its MAC address table to determine whether it knows which port to send the server's traffic to in this case it does, so it sends the return traffic out only its Fa0/3 port (PC1), without flooding. The switch would receive the frame and create a new entry in its MAC address table for the server's MAC address (Server -> Fa0/2). Assuming that the server wants to respond to PC1, it would sent a new frame back toward the switch. The switch would then perform a lookup on its MAC address table to determine whether it knows which port to send the traffic to since no matching entries exist in the switch's tables, it would flood the frame out all of its interfaces (except the receiving port).īecause the frame was sent out to all of the switch's other ports, it would be received by the target server. The first thing the switch would do when receiving the traffic is create a new entry in its MAC address table for PC1's MAC address (PC1 -> Fa0/3). It would encapsulate an Ethernet frame and send it off toward the switch.

Now suppose PC1 wants to send traffic to the server that has a MAC address of 00:00:00:00:00:01. In this case, the MAC address table of the switch would be empty (ignoring any system MAC addresses shown in the table by default). Let's assume that all of the devices are powered on but have not sent any traffic.

In Figure 1, a switch is surrounded by a number of common devices.

Dynamically allow the switch to learn mac addresses of pcs on vlan