DCCN unit-4

https://drive.google.com/file/d/1xo_gUlKN2u49I0zBJFJdkFTL4ydENqKg/view?usp=sharing https://drive.google.com/file/d/1uZCgMjSFDgVICUdf9Hf67Ze5aPY8wrXj/view?usp=sharing https://docs.google.com/document/d/1vUHPmB4OtV1KlaCb1fwLvOAGpHrfMBvC/edit?usp=sharing&ouid=112711162618141236570&rtpof=true&sd=true

The transport layer protocols, primarily TCP and UDP, manage process-to-process delivery, often achieved through the client/server paradigm. TCP (Transmission Control Protocol) is a connection-oriented, reliable protocol that establishes a connection before communication, ensures data is received in order, and uses mechanisms like sequence numbers, acknowledgments, flow control, and congestion control. Its reliability comes with higher overhead and slower speed compared to UDP. TCP handles data as a stream of bytes, using buffers and segment creation for transmission. Key features of TCP include the three-way handshaking for connection establishment and error control using checksums, acknowledgments, and retransmission. UDP (User Datagram Protocol), in contrast, is a connectionless and unreliable protocol that sends data directly without establishing a connection or guaranteeing delivery or order. It is faster due to its low overhead and is used when speed is prioritized over reliability, such as in streaming or online gaming. Both protocols use socket addresses (IP address and port number) for process identification. The document also covers congestion control mechanisms like open-loop (e.g., Retransmission Policy, Window Policy) and closed-loop (e.g., Back Pressure, Choke Packet, Implicit/Explicit Signaling), as well as Quality of Service (QoS) models like Integrated Services (IntServ) and Differentiated Services (DiffServ).

Here are 5 key topics covered:

• Process-to-Process Delivery: The primary function of a transport-layer protocol, which allows an application layer entity (process) on one host to communicate with an application layer entity on a remote host.
• TCP (Transmission Control Protocol): A connection-oriented, reliable protocol that ensures ordered, error-free delivery through mechanisms like sequence numbers, acknowledgments, flow control, and congestion control.
• UDP (User Datagram Protocol): A connectionless, unreliable protocol that sends data directly without connection establishment or guaranteed delivery, making it faster than TCP.
• Congestion Control: Mechanisms and techniques used to control network congestion, keeping the data load below the network's capacity. These are broadly categorized into open-loop (prevention) and closed-loop (removal) methods.
• Quality of Service (QoS): An overall performance measure of a computer network, with important flow characteristics including reliability, delay, jitter (variation in packet delay), and bandwidth.