Transmission Control Protocol/Internet Protocol (TCP/IP) is a suite of standard protocols for connecting computers and building networks. TCP/IP is network protocol software provided with Microsoft® Windows® operating systems that implements and supports the TCP/IP protocol suite:

Display name: TCP/IP Protocol Driver Service name: Tcpip Type: kernel Path: %WinDir%\System32\drivers\tcpip.sys

Core protocols of TCP/IPThis section covers:

Address Resolution Protocol (ARP)

Internet Protocol (IP)

Internet Control Message Protocol (ICMP)

Internet Group Management Protocol (IGMP)

User Datagram Protocol (UDP)

Transmission Control Protocol (TCP)


IP addressing and routingThis section covers:

IP addressing

Subnet masks

IP routing

The IP routing table

The TCP/IP modelTCP/IP is based on a four-layer reference model. All protocols that belong to the TCP/IP protocol suite are located in the top three layers of this model.

As shown in the following illustration, each layer of the TCP/IP model corresponds to one or more layers of the seven-layer Open Systems Interconnection (OSI) reference model proposed by the International Standards Organization (ISO).


Layer Description  Protocols

Application Defines TCP/IP application protocols and how host programs interface with transport layer services to use the network. HTTP, Telnet, FTP, TFTP, SNMP, DNS, SMTP, X Windows, other application protocols

Transport Provides communication session management between host computers. Defines the level of service and status of the connection used when transporting data. TCP, UDP, RTP

Internet Packages data into IP datagrams, which contain source and destination address information that is used to forward the datagrams between hosts and across networks. Performs routing of IP datagrams. IP, ICMP, ARP, RARP

Network interface Specifies details of how data is physically sent through the network, including how bits are electrically signaled by hardware devices that interface directly with a network medium, such as coaxial cable, optical fiber, or twisted-pair copper wire. Ethernet, Token Ring, FDDI, X.25, Frame Relay, RS-232, v.35


Guarantees delivery of IP datagrams.


Ensures proper sequencing and ordered delivery of segmented data.




How TCP works





TCP ports







TCP port number Description 

20 FTP server (data channel)

21 FTP server (control channel)

23 Telnet server

53 Domain Name System zone transfers

80 Web server (HTTP)

139 NetBIOS session service