TCP vs UDP

Difference between TCP and UDP
Transmissions Control Protocol (TCP) and User datagram Protocol (UDP) are 2 most
commonly used protocol in TCP/IP. In this article you will see the complete comparison
between TCP and UDP.
In nutshell, TCP is a reliable protocol and offers are guaranteed delivery, However UDP is un
reliable and does not provide any guarantee of deliver. Go here for complete UDP and TCP
comparison and click this link for TCP, UDP details.
TCP (Transmission Control Protocol)
UDP (User Datagram Protocol)
TCP Protocol Number is 6 UDP Protocol Number : 17
TCP is Reliable and thus offers guaranteed delivery
Unreliable and no guarantee of delivery
Connection Oriented Protocol ( Forms connection
before transmit)
Has mechanism of Flow Control and retransmission
Uses concept of sequencing thus order of packets is
maintained
Acknowledgement of Segments done
Connectionless Protocol
No mechanism of flow control and
retransmission
No Sequencing
No Acknowledgements
Low transmission compared to UDP
High Speed transmission
More overhead on TCP due to additional features
Less Overhead
Uses mechanism of 3 way handshake to establish
connection : SYN, SYN-ACK, ACK
Header Size larger than UDP : Heavy Weight
No handshake as UDP is a connectionless
protocol
Header Size smaller than TCP : Lightweight

TCP offers Error correction
Used for other applications like webpages or
critical applications
Fields in Header: Source Port, Destination Port,
Sequence number, ACK number, Data Offset,
Reserved, Control bit (Flags), Window, Checksum,
Urgent Pointer, Options, Padding
Protocol Examples: FTP, HTTP, SMTP, DNS etc.
UDP does error checking but no correction or
recovery done in case of errors found
Used for Streaming Audio & Video
Fields in Header: Source Port, Destination Port,
Length, UDP Checksum
Protocol Example: DNS, SNMP, TFTP, BOOTP
etc.
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