Delivering message through LAN:
We have to devise method for delivering message through LAN phase to single, specific destination device. Sending device uses a hardware address to identify the intended position of a frame. The sending device also identifies kind of data carried in the frame.
SPECIFYING A DESTINATION:
The data transmit across a shared network reaches every attached stations - for all LAN topologies. Interface hardware finds delivery of frame and extracts frame from phase. But most applications need data to be send to one specific program on another device but not all computers.
HARDWARE ADDRESSING:
Most network methods have a hardware-addressing function that identifies stations on the network. Every station is given a physical address or numeric hardware address. Sender also adds hardware address in every transmitted frame. In that way only station identified in frame accept copy of frame. Most LAN methods include sender's hardware address in packet frame too.