Computer Communication: Locally and Remotely

The following pieces of information must be with a computer to communicate over TCP/IP network →

If you run the ipconfig command you will see the details about your network, including:

  • Physical Address of your device (MAC).
  • IP address along with subnet mask.
  • Default Gateway (the router assigned for sending IP packets).
  • DNS Server IP

Computer A wants to talk to B and C. The computer A uses its subnet mask to find out if B and C are local or remote. Then to communicate locally with B, A follows:

  • Step 1: A asks for B’s MAC Address using ARP.
  • Step 2: B replies to A with its MAC Address.
  • Step 3: A uses frames to communicate with B.

All communications between A and B would require a switch (layer 2 device). The default gateway(layer 3 device) will not be used in this case.

Now, let’s see how A talks with C:

  • Step 1: A asks for the MAC address of the default gateway using ARP.
  • Step 2: The default gateway replies to A with its MAC Address.
  • Step 3: A sends its IP packets to the default gateway, which delivers the message of A to C.

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