Transmission Control Protocol

A Simplified TCP State Diagram. See TCP EFSM diagram for a more detailed state diagram including the states inside the ESTABLISHED state.
Connection termination
TCP sequence numbers and receive windows behave very much like a clock. The receive window shifts each time the receiver receives and acknowledges a new segment of data. Once it runs out of sequence numbers, the sequence number loops back to 0.

One of the main protocols of the Internet protocol suite.

- Transmission Control Protocol

500 related topics


Transport layer

Conceptual division of methods in the layered architecture of protocols in the network stack in the Internet protocol suite and the OSI model.

The transport layer in the Internet protocol stack.

The best-known transport protocol of the Internet protocol suite is the Transmission Control Protocol (TCP).

User Datagram Protocol

One of the core members of the Internet protocol suite.

Network Packet

If error-correction facilities are needed at the network interface level, an application may instead use Transmission Control Protocol (TCP) or Stream Control Transmission Protocol (SCTP) which are designed for this purpose.

Reliability (computer networking)

Communication protocol that notifies the sender whether or not the delivery of data to intended recipients was successful.

Network Packet

Transmission Control Protocol (TCP), the main protocol used on the Internet, is a reliable unicast protocol.

Latency (engineering)

Time delay between the cause and the effect of some physical change in the system being observed.

Why-Because Graph of the capsizing of the Herald of Free Enterprise (click to see in detail).

Ping cannot perform accurate measurements, principally because ICMP is intended only for diagnostic or control purposes, and differs from real communication protocols such as TCP.

Internet protocol suite

Set of communications protocols used in the Internet and similar computer networks.

Diagram of the first internetworked connection
An SRI International Packet Radio Van, used for the first three-way internetworked transmission.
Conceptual data flow in a simple network topology of two hosts (A and B) connected by a link between their respective routers. The application on each host executes read and write operations as if the processes were directly connected to each other by some kind of data pipe. After establishment of this pipe, most details of the communication are hidden from each process, as the underlying principles of communication are implemented in the lower protocol layers. In analogy, at the transport layer the communication appears as host-to-host, without knowledge of the application data structures and the connecting routers, while at the internetworking layer, individual network boundaries are traversed at each router.
Encapsulation of application data descending through the layers described in RFC 1122

The current foundational protocols in the suite are the Transmission Control Protocol (TCP) and the Internet Protocol (IP), as well as the User Datagram Protocol (UDP).

Bob Kahn

Kahn in Geneva, May 2013
Vint Cerf and Robert Kahn being awarded the Presidential Medal Of Freedom by President Bush

Robert Elliot Kahn (born December 23, 1938) is an American electrical engineer, who, along with Vint Cerf, first proposed the Transmission Control Protocol (TCP) and the Internet Protocol (IP), the fundamental communication protocols at the heart of the Internet.


Basic transfer unit associated with a packet-switched network.

An animation demonstrating datagram type of packet switching across a network

The Cyclades team has thus been first to tackle the highly complex problem of providing to user applications a reliable virtual circuit service (the equivalent of an Internet TCP connection) while using an end to end network service known to possibly produce non negligible datagram losses and permutations.

Network congestion

Reduced quality of service that occurs when a network node or link is carrying more data than it can handle.

Network Packet

These include: exponential backoff in protocols such as CSMA/CA in 802.11 and the similar CSMA/CD in the original Ethernet, window reduction in TCP, and fair queueing in devices such as routers and network switches.


Fourth version of the Internet Protocol (IP).

IPv4 packet
Decomposition of the quad-dotted IPv4 address representation to its binary value

These aspects, including data integrity, are addressed by an upper layer transport protocol, such as the Transmission Control Protocol (TCP).

Connection-oriented communication

Network communication mode in telecommunications and computer networking, where a communication session or a semi-permanent connection is established before any useful data can be transferred.

Charles Babbage, sometimes referred to as the "father of computing".

In the latter case, it may use either a transport layer virtual circuit protocol such as the TCP protocol, allowing data to be delivered in order.