The TCP/IP protocols in an internet utilize four tiers of addresses: physical (link) addresses, logical (IP) addresses, port addresses, and specialized addresses.
Physical Addresses
The physical address, sometimes referred to as the link address, is the specific address of a node as determined by its local area network (LAN) or wide area network (WAN). It is encompassed within the framework utilized by the data link layer. It is the address at the lowest level. The physical addresses possess control over the network, whether it is a Local Area Network (LAN) or a Wide Area Network (WAN). The dimensions and configuration of these addresses differ based on the network. As an illustration, Ethernet employs a 6-byte (48-bit) physical address that is permanently marked on the network interface card (NIC).
Logical addresses
Logical addresses are essential for facilitating universal communication that is not reliant on specific physical networks. Physical addresses are insufficient in an internetwork context due to the presence of various networks with distinct address formats. An imperative requirement is the establishment of a universal addressing system that can assign a unique identification to each host, irrespective of the underlying physical network. The logical addresses are specifically developed for this purpose. Currently, an Internet logical address is a 32-bit address that has the ability to uniquely identify a host that is connected to the Internet. It is impossible for two hosts that are publicly addressed and accessible on the Internet to share the same IP address.
Port addresses
Both the IP address and the physical address are essential for transmitting data from a source to a destination host. Nevertheless, reaching the destination host is not the ultimate goal of data transmission on the Internet. A system that solely transmits data between computers is insufficient. In the present day, computers are sophisticated machines capable of executing numerous processes simultaneously. The ultimate goal of Internet communication is the exchange of information between two computer processes. Computer A can establish communication with computer C using the TELNET protocol. Simultaneously, computer A establishes communication with computer B through the utilization of the File Transfer Protocol (FTP). In order for these processes to receive data at the same time, it is necessary to have a mechanism to categorize or identify the various activities. Put simply, they require addresses. In the TCP/IP architecture, a process is issued a label known as a port address. The length of a port address in TCPIIP is 16 bits.
Specific Addresses
Certain programs feature addresses that are specifically designed to be user-friendly for that particular address. Examples encompass the e-mail address, such as xyz@pqr.com, and the Universal Resource Locator (URL), such as www.abc.com. The first term refers to the intended receiver of an electronic communication, while the second term is employed to locate a specific file on the global network known as the World Wide Web. However, the sender computer converts these addresses to their appropriate port and logical addresses.
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