RFTCP vs UDP: Key Differences Explained
This article explores the key differences between TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). Both protocols operate at Layer 4 (the Transport Layer) of the OSI model, sitting just above the IP layer.
Unlike TCP, UDP is connectionless. It doesn’t guarantee reliability, doesn’t implement windowing, and doesn’t ensure that data is received in the same order it was transmitted.
However, UDP offers functionalities such as data transfer and multiplexing, with fewer overhead bytes in its data packets. This smaller overhead means UDP requires less time to process each packet and less memory. The absence of an acknowledgement field also speeds things up, as UDP doesn’t need to wait for ACKs or hold data in memory until they are acknowledged.
Let’s break down the differences in more detail:
| Feature | TCP | UDP |
|---|---|---|
| Definition | Defined in RFC793 | Defined in RFC768 |
| Full Form | Transmission Control Protocol | User Datagram Protocol |
| Connection Type | Connection-oriented service | Connectionless service |
| Reliability | Reliable, in-order byte-stream protocol | Unreliable, un-ordered packet protocol |
| Reliability Mechanisms | Considered highly reliable due to SYN and acknowledgement fields | Considered an unreliable service protocol |
| Protocol Field in IP Header | 0x06 (decimal 6) | 0x11 (decimal 17) |
| Header Structure | Consists of source port, destination port, sequence number, acknowledgement number, header length, flags (U, A, P, R, S, F), window, checksum, pointer, and padding bits. See image below. | Consists of source port, destination port, segment length, and checksum. See image below. |
| Data Transfer | Continuous stream of ordered data, segmented before transmission. | Message-based datagram delivery. |
| Multiplexing | Receiving hosts determine the correct application for the data based on the port number field (2 bytes). | Receiving hosts determine the correct application for the data based on the port number field (2 bytes). |
| Flow Control | Uses window size to protect buffer space and routing devices. | Not supported in UDP. |
TCP Header Structure
TCP Header
UDP Header Structure
UDP Header
