Answer:
The Transport Layer is the fourth layer of the OSI (Open Systems Interconnection) model and is responsible for the reliable transfer of data between applications running on different hosts. The Transport Layer provides end-to-end communication services that ensure that data is delivered correctly, completely, and in order. This layer is responsible for breaking up large data packets into smaller ones, ensuring the integrity of data through error checking and correction, and reassembling packets into their original form at the receiving end. The two most commonly used Transport Layer protocols are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
TCP is a connection-oriented protocol that establishes a virtual circuit between the sender and receiver before data is exchanged. It ensures that data is delivered reliably, and in order, by implementing flow control, congestion control, and error detection and correction mechanisms. TCP guarantees the delivery of data packets, but this comes at the cost of increased overhead and latency, making it more suitable for applications where reliability is crucial, such as file transfers, email, and web browsing.
UDP, on the other hand, is a connectionless protocol that sends data packets without establishing a virtual circuit beforehand. UDP is faster and more efficient than TCP, as it has lower overhead and latency, but it does not guarantee the delivery of packets, and packets may arrive out of order. UDP is more suitable for real-time applications, such as video streaming and online gaming, where speed is more important than reliability.
Port addressing is a method used by the Transport Layer to identify which application is sending or receiving data. Each application running on a host is assigned a unique port number, and this port number is included in the header of the Transport Layer packet to ensure that data is delivered to the correct application. Port addressing is different from Logical (IP) addressing and Physical (MAC) addressing, which are used to identify the source and destination hosts.
Logical (IP) addressing is used by the Network Layer to identify the source and destination hosts. Every device on a network is assigned a unique IP address, which is used to route data packets between hosts. Physical (MAC) addressing is used by the Data Link Layer to identify the physical hardware address of a device. MAC addresses are unique identifiers assigned to each network interface card (NIC) and are used to deliver data packets to the correct physical device on a network.
We need port addressing, logical addressing, and physical addressing to ensure that data is delivered correctly to its intended destination. Each layer of the OSI model performs a specific function, and the different addressing schemes are used to ensure that data is delivered reliably and efficiently across a network. Without these addressing schemes, data would not be able to be delivered accurately, and network communication would not be possible.
Step-by-step explanation: