TCP/IP (Transmission Control Protocol/Internet Protocol)

What is TCP/IP (Transmission Control Protocol/Internet Protocol)?

TCP/IP, or Transmission Control Protocol/Internet Protocol, is a suite of communication protocols used to interconnect network devices on the internet. TCP/IP can also be used as a communications protocol in a private computer network (an intranet or extranet).

The entire IP suite -- a set of rules and procedures -- is commonly referred to as TCP/IP. TCP and IP are the two main protocols, though others are included in the suite. The TCP/IP protocol suite functions as an abstraction layer between internet applications and the routing/switching fabric.

TCP/IP specifies how data is exchanged over the internet by providing end-to-end communications that identify how it should be broken into packets, addressed, transmitted, routed, and received at the destination. TCP/IP requires little central management and is designed to make networks reliable with the ability to recover automatically from the failure of any device on the network.[1]

The TCP/IP model was developed by the United States Department of Defense to enable the accurate and correct transmission of data between devices. It breaks messages into packets to avoid having to resend the entire message in case it encounters a problem during transmission. Packets are reassembled once they reach their destination. Every packet can take a different route between the source and the destination computer, depending on whether the original route used becomes congested or unavailable.

TCP/IP divides communication tasks into layers that keep the process standardized, without hardware and software providers having to try and manage it themselves. The data packets must pass through four layers before they are received by the destination device, then TCP/IP goes through the layers in reverse order to put the message back into its original format.

As a connection-oriented protocol, TCP establishes and maintains a connection between applications or devices until they finish exchanging data. It determines how the original message should be broken into packets, numbers and reassembles the packets, and sends them on to other devices on the network, such as routers, security gateways, and switches, then on to their destination. TCP also sends and receives packets from the network layer, handles the transmission of any dropped packets, manages flow control, and ensures all packets reach their destination.

A good example of how this works in practice is when an email is sent using SMTP from an email server. The TCP layer in the server divides the message into packets, numbers them, and forwards them to the IP layer, which then transports each packet to the destination email server. When packets arrive, they are handed back to the TCP layer to be reassembled into the original message format and handed back to the email server, which delivers the message to a user’s email inbox.

TCP/IP uses a three-way handshake to establish a connection between a device and a server, which ensures multiple TCP socket connections can be transferred in both directions concurrently. Both the device and server must synchronize and acknowledge packets before communication begins, then they can negotiate, separate, and transfer TCP socket connections.[2]

See Also

Network Protocol
Protocol Stack
Internet Protocol (IP)
File Transfer Protocol (FTP)
POP (Post Office Protocol)
VoIP (Voice Over Internet Protocol)
Time Triggered Protocol (TTP) Extensible Authentication Protocol (EAP)
Hypertext Transfer Protocol (HTTP)
User Datagram Protocol (UDP)
Protocol Data Unit (PDU)
Network Control Program (NCP)
Transmission Control Protocol (TCP)
Business Transaction Protocol (BTP)
Common Alerting Protocol (CAP)
SMTP (Simple Mail Transfer Protocol)
Advanced Message Queuing Protocol (AMQP)
Simple Object Access Protocol (SOAP)
Internet Message Access Protocol (IMAP)
IP Network
Ethernet Industrial Protocol (Ethernet/IP)
Simple Network Management Protocol (SNMP)
Access Media Gateways (AMG)
Secure Sockets Layer (SSL)
Internet Message Access Protocol (IMAP)
Synchronous Optical Network (SONET)
IP Address
Digital Subscriber Line (DSL)