The TCP/IP Model

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The TCP/IP (Transmission Control Protocol/Internet Protocol) model, which resembles the OSI model, consists of four layers:

Application layer corresponds to OSI Application and Presentation layers, and it directly supports application programs. Transport layer corresponds to OSI Session and Transport layers. It creates packets and reassembles messages, guarantees delivery, receives and acknowledges each packet, and sends and re-sends unacknowledged packets.

• Internet layer corresponds to OSI Network layer [IP (Internet Protocol)], and it routes and delivers individual packets.

Network Access layer corresponds to OSI Data Link and Physical layers. This is where Ethernet, token ring and other network access protocols reside.