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Connection
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TCP is a connection-oriented protocol. |
UDP is a connectionless protocol. |
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| Function |
As a message makes its way across the internetfrom one computer to another. This is connection based. |
UDP is also a protocol used in message transport or transfer. This is not connection based which means that one program can send a load of packets to another and that would be the end of the relationship. |
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| Usage |
TCP is suited for applications that require high reliability, and transmission time is relatively less critical. |
UDP is suitable for applications that need fast, efficient transmission, such as games. UDP‘s stateless nature is also useful for servers that answer small queries from huge numbers of clients. |
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| Use by other protocols |
HTTP, HTTPs, FTP, SMTP, Telnet |
DNS, DHCP, TFTP, SNMP, RIP, VOIP. |
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| Ordering of data packets |
TCP rearranges datapackets in the order specified. |
UDP has no inherent order as all packets are independent of each other. If ordering is required, it has to be managed by the application layer. |
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| Speed of transfer |
The speed for TCP is slower than UDP. |
UDP is faster because error recovery is not attempted. It is a "best effort" protocol. |
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| Reliability |
There is absolute guarantee that the data transferred remains intact and arrives in the same order in which it was sent. |
There is no guarantee that the messages or packets sent would reach at all. |
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| Header Size |
TCP header size is 20 bytes |
UDP Header size is 8 bytes. |
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| Common Header Fields |
Source port, Destination port, Check Sum |
Source port, Destination port, Check Sum |
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| Streaming of data |
Data is read as a byte stream, no distinguishing indications are transmitted to signal message (segment) boundaries. |
Packets are sent individually and are checked for integrity only if they arrive. Packets have definite boundaries which are honored upon receipt, meaning a read operation at the receiver socket will yield an entire message as it was originally sent. |
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| Weight |
TCP is heavy-weight. TCP requires three packets to set up a socket connection, before any user data can be sent. TCP handles reliability and congestion control. |
UDP is lightweight. There is no ordering of messages, no tracking connections, etc. It is a small transport layer designed on top of IP. |
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| Data Flow Control |
TCP does Flow Control. TCP requires three packets to set up a socket connection, before any user data can be sent. TCP handles reliability and congestion control. |
UDP does not have an option for flow control |
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