This was to illustrate the communication between and the separate machines which don ' t have a direct physical connection.
Application data is generated and passed to Layer 3 (network layer) which wrapps up the data with the destination IP Addre Ss. Then hands to Layer 2 (link layer) which have a lookup table of IP addresses and their corresponding MAC addresses in the L Ocal network. Layer 2 looks at the IP address and try to resolve the IP address. If The IP address is in the table, it'll wrap the Layer 3 envelope in a layer 2 envelop with the MAC address in the head The ER and then passes to physical layer to do the data communication.
Alternatively, if IP address is not in the lookup table, it would have the MAC address of default gateway (i.e. router) and Forward data to the router the routers notices that the envelope have its own MAC address. It opens the Layer 2 envelope, look at the IP address and works out where to send the message, which probably forward T o the ISP router. These steps repeat untill data is sent to the destination.
- MAC address is not being routed to router. It is only used for the communication inside the local physical network (LAN)
- It is on Layer 2 that MAC address starts playing the game.
- IP addresses cover the whole Internet and routers use them to figure out where to send the data
IF Application data needs to is sent to the IP address xx.xx.xx.xx, how does does it work in underneath network?