2.4 Networking Addressing

1. Successful network communication requires that both sender and receiver know the (logical) address of each other.
2. A network address serves as a unique identifier for a computer on a network.
3. Addressing of data happens in transport, network, and data link layers.

2.4 Networking Addressing

		At the transport layer, information contained in the PDU header identifies a specific task running
		on the destination. The transport layer adds port numbers to its segment header information to ensure
		that the destination knows which application process is to receive the packet. The end device assigns
		a port number to each type of traffic going in and out, where a port number is a way to identify a
		specific process to which network message is to be forwarded when it arrives at a destination.
		At the network layer, information contained in the PDU header includes identifiers that enable
		intermediary network devices to locate end device on different networks. In the TCP/IP protocol
		suite, every IP end device address contains information about the network where the end
		device is located.
		The physical address of the host is contained in the header of the Layer 2 PDU (frame),
		where the physical address (sometimes called Media Access Control address MAC) comes
		from codes placed on the NIC by the manufacturer.