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Explain the purpose of MAC address table in a switch.

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A MAC (Media Access Control) address table, also known as a MAC address forwarding table or content addressable memory (CAM) table, plays a crucial role in the operation of network switches. Switches operate at the data link layer (Layer 2) of the OSI model and use MAC addresses to forward frames within a local area network (LAN). The purpose of the MAC address table in a switch is to facilitate the efficient forwarding of data frames between devices on the same network. Here's how it works:

  1. Address Learning:
    • When a switch receives a frame from a device connected to one of its ports, it examines the source MAC address in the frame.
    • The switch updates its MAC address table with the source MAC address, associating it with the port on which it was received.
  2. Address Forwarding:
    • When the switch receives a frame destined for a specific MAC address, it consults its MAC address table.
    • If the MAC address is found in the table, the switch forwards the frame only to the port associated with that MAC address, avoiding unnecessary broadcast to all ports.
    • If the MAC address is not in the table or the entry is outdated, the switch may flood the frame to all ports except the one it was received on (broadcast), learning the correct port for that MAC address in the process.
  3. Efficient Frame Forwarding:
    • By maintaining the MAC address table, switches make forwarding decisions based on MAC addresses, allowing them to forward frames directly to the appropriate destination port.
    • This process reduces unnecessary network traffic and improves the overall efficiency of the network.
  4. Filtering and Security:
    • The MAC address table helps the switch filter frames by only forwarding them to the intended destination. This enhances network security and reduces the likelihood of unauthorized devices accessing the network.

The MAC address table in a switch is a dynamic database that maps MAC addresses to specific switch ports. It enables the switch to make informed forwarding decisions, minimizing unnecessary traffic and optimizing the efficiency of data transmission within a local network.