If the MAC address table on a switch is empty, how will the frame from PC-A be handled when sent to PC-C?

If the MAC address table on a switch is empty, how will the frame from PC-A be handled when sent to PC-C?

• A. SW ignores the frame completely
• B. SW forwards the frame only to PC-B
• C. SW floods the frame on all the ports on SW1, excluding the port through which the frame entered
• D. SW forwards the frame to the default gateway

Answer: (C)

When a switch receives a frame and its MAC address table is empty, it does not have any entries to know which port to send the frame to for the specific destination MAC address. In this scenario, the switch will handle the incoming frame by flooding it out on all ports except the port it came from. This process allows the switch to learn which device is connected to which port. As the frame is flooded, all connected devices, including PC-B and PC-C, will receive a copy of the sent frame. Only the intended recipient, in this case PC-C, will respond and send a reply back, allowing the switch to learn PC-C's MAC address and the port it is connected to. Over time, this learning process helps the switch build its MAC address table, thus decreasing the need for flooding in future communications to that device. Flooding is a fundamental behavior of Ethernet switches, designed to support dynamic network configurations where devices can connect or disconnect without prior knowledge of their locations in the network. This mechanism ensures that frames can be reliably delivered, even in the absence of prior knowledge about the MAC address locations.

When a switch receives a frame and its MAC address table is empty, it does not have any entries to know which port to send the frame to for the specific destination MAC address. In this scenario, the switch will handle the incoming frame by flooding it out on all ports except the port it came from. This process allows the switch to learn which device is connected to which port.

As the frame is flooded, all connected devices, including PC-B and PC-C, will receive a copy of the sent frame. Only the intended recipient, in this case PC-C, will respond and send a reply back, allowing the switch to learn PC-C's MAC address and the port it is connected to. Over time, this learning process helps the switch build its MAC address table, thus decreasing the need for flooding in future communications to that device.

Flooding is a fundamental behavior of Ethernet switches, designed to support dynamic network configurations where devices can connect or disconnect without prior knowledge of their locations in the network. This mechanism ensures that frames can be reliably delivered, even in the absence of prior knowledge about the MAC address locations.