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Ethernet Switches


  • Ethernet is a layer 2 protocol that is widely used to create LANs
  • Ethernet networks are created using layer 2 devices called switches

Ethernet switch#

  • A switch is a layer 2 devices used to create LANs
  • An ethernet frame is used for communication among the devices connected in the network
  • The frame header contains the source and destination MAC address
  • The switch delivers the ethernet frame to the device with the MAC address as specified in the frame header
  • The switch uses a MAC address table to keep track of the MAC addresses of the devices and the ports on the switch to which the devices are connected.
  • When two switches are connected the redundant paths must be excluded while broadcasting data otherwise there would be a broadcast storm


  • When one device wants to send a data to another device in the LAN, the sender must be aware of the destination MAC address
  • ARP(Address Resolution Protocol) is used by the hosts to find the MAC address of the destination device by sending an ARP request to the network specifying the destination IP address, the device with the IP address specified responds with it’s MAC address
  • The hosts keep a MAC address table as cache