Transport Layer Protocols: TCP & UDP

Transport Layer in Networking

• Facilitates communication between applications on hosts.
• TCP is a reliable transport layer protocol for data transmission.
• UDP is a connectionless transport layer protocol for faster communication.
• Conversation describes data flow between source and destination applications.
• Segmenting Data involves dividing application data into manageable blocks.
• Reassembling Segments combines data blocks to form complete data streams.
• Header Information is binary data added to each block for management; it identifies target applications in streams.
• Port Numbers are identifiers for applications in data streams.
• Transport Layer Responsibilities include tracking, segmenting, and identifying applications.
• Logical Communication describes abstract communication between applications across networks.
• Data Blocks, also called segments or datagrams, are created for data transport.
• Multiple Conversations are tracked by the transport layer.
• Application Layer handles application-specific data above the transport layer.
• Network Transmission is managed by lower layers, which handle actual data transport.
• Congestion Awareness is not a transport layer concern (transport layer does not consider network congestion).
• Data Packet Limitation describes network limits on data size in packets.
• Transport Protocols function uniquely to handle communication.
• Receiving Host reassembles data for application use.
• Transport Layer Protocols include TCP and UDP.
• Unique Port Assignment assigns distinct port numbers to each application process.
• Data Stream is the continuous flow of data between applications.
• Transmission Control ensures reliable data packet delivery.
• User Datagram Protocol (UDP) is a fast but less reliable alternative to TCP.
• Conversation Multiplexing intertwines multiple communications on the same network.
• Segmentation divides data for transmission.
• Error Checking verifies data integrity during transmission.
• Transport Layer Protocols manage message transfer between hosts.
• TCP is a reliable, connection-oriented transport layer protocol.
• UDP is an unreliable, connectionless transport layer protocol.
• Different applications have differing reliability needs.
• Transmission Control Protocol ensures complete data delivery to the destination.
• Flow Control regulates data transmission rates between sender and receiver.
• Data Segments are units of data tracked by TCP during transmission.
• Connection-Oriented Protocol establishes a connection before data transfer.
• Stateful Protocol tracks communication session states.
• Session Establishment is the initial phase of a TCP connection.
• Session Termination is the closing phase of a TCP connection.
• TCP Segment Overhead adds 20 bytes to encapsulate application data.
• Source Port, Destination Port, Sequence Number, Acknowledgment Number, Header Length, Reserved Field, Control Bits, Window Size, Checksum, Urgent Pointer are components of a TCP Segment header.
• Simpler, connectionless transport layer protocol is User Datagram Protocol (UDP).
• UDP Reliability: UDP lacks mechanisms for reliable data delivery and does not ensure delivery.
• UDP Flow Control: lacks mechanisms for controlling data flow.
• UDP Datagrams are blocks of communication in UDP.
• UDP has a stateless protocol, meaning it does not maintain communication session state.
• UDP Best-Effort Delivery: no acknowledgment of data receipt.
• UDP Header contains four fields needing 8 bytes.
• UDP Source Port identifies the source application.
• UDP Destination Port identifies the destination application.
• UDP Sequence Number is used for data reassembly.
• UDP Length indicates datagram header length.
• Socket in UDP is a combination of IP address and port number.
• UDP Encapsulation: segments are encapsulated in an IP packet.
• Application Layer handling reliability (as required) in UDPD.
• Live video, voice applications better suited to UDP via speed.
• UDP Overhead is minimal compared to TCP.
• Port Number distinguishes applications in sockets.
• Ports 0-1023 are well-known ports reserved for specific services.
• Dynamic Ports are assigned temporarily to client requests.
• TCP is Transmission Control Protocol for reliable communication.
• Three-way Handshake is a procedure for establishing a TCP connection.
• Client Request initiates communication from client to server.
• Server Response is from the server to a client request.
• Port Configuration involves manual or automatic port number assignment.
• Active Server Application actively listens on a specified port.
• Response Destination Port is the port in the server response and originally the client source port.
• Response Source Port is the port in the server response and originally the client destination port.
• Email Service typically uses SMTP on port 25.
• Source Port Example can be port 49152.
• Destination Port Example, for web requests could be 49152.
• SYN is for initiating a communication session.
• ACK is acknowledgement of the received communication session.
• FIN is the control flag to terminate a TCP session.
• Control Bits for TCP describe TCP segment purpose.
• Full-duplex protocols allow simultaneous two-way communication.
• Session termination closes an active TCP session.
• Two-way Handshake ends one-way TCP sessions.
• Four Exchanges are needed to terminate a single TCP conversation.
• Client is an initiating host in a communication session.
• Server is a receiving host in a communication session.
• Active Service signifies that a server is ready to accept requests on an opened port.
• Segment Header includes control bits and sequence numbers.
• Push Function (PSH) ensures immediate data processing by the recipient.
• Reset Connection (RST) aborts a connection.
• Urgent Pointer (URG) signals urgent data in the TCP segment.
• Sequence Numbers track data segments in TCP.
• Acknowledgments (ACK) confirm receipt of TCP segments.
• Connection Termination is the protocol for closing a TCP connection.
• Session Closure occurs when all segments are acknowledged.
• Destination Port Number identifies the communication port of the server.
• Communication Session is communication between hosts.
• TCP 3-Way Handshake is a process to establish a TCP connection.
• Wireshark is a network traffic analysis tool.
• tcpdump is a command-line packet analyzer.
• TCP Segments are packets transmitted over TCP connections.
• Sequence Number identifies the initial byte in a TCP segment.
• Initial Sequence Number (ISN) is the starting value for transmitted byte tracking.
• Data Reassembly reconstructs original data from segments.
• Receiving Buffer stores incoming TCP segment data.
• Out-of-Order Segments are segments received out of their expected sequence.
• Expectational Acknowledgement indicates next anticipated byte from the receiver.
• Acknowledgement Number (ACK) specifies the next expected byte.
• Segment Loss is when segments fail to reach their destination.
• Retransmission resends lost TCP segments.
• Congestion describes network overload causing transmission delays.
• TCP Services ensure data delivery and integrity.
• Data Loss Management defines methods for handling lost TCP segments.
• Duplicate Segments are segments that have been received previously.
• Session Setup establishes a TCP connection.
• Receiving Process handles incoming TCP segments.
• Segment Identification tracks TCP segments.
• TCP Header contains sequence and acknowledgment numbers.
• Packet Analysis examines data packets for troubleshooting.
• Selective Acknowledgment (SACK) is a TCP feature for acknowledging received segments.
• Three-Way Handshake is the initial setup process for TCP connections.
• Data Loss occurs when transmitted data segments are not received.
• Retransmission resends lost segments.
• Flow Control manages data transmission rates.
• Window Size defines the bytes that can be sent before acknowledgment.
• Acknowledgment Number specifies the next expected byte.
• Sliding Windows dynamically adjust the sending window based on acknowledgments.
• Maximum Segment Size (MSS) is the largest data size in a single TCP segment.
• TCP Header contains control information for TCP segments.
• Buffer Availability is the available space for incoming data.
• Destination Device receives TCP segments.
• Source Device sends TCP segments.
• Discontinuous Segments are non-sequential segments; received segments not in order.

Additional Information

• FTP (File Transfer Protocol) uses port 21.
• Web services typically use port 80.

Test your knowledge of transport layer protocols like TCP and UDP. Explore key concepts such as guaranteed data delivery, sequence numbers, and the three-way handshake. Learn about the roles of dynamic ports and conversation multiplexing in network communication.