The Defense Advance Research Projects Agency (DARPA) originally developed Transmission Control Protocol/Internet Protocol (TCP/IP) to interconnect various defense department computer networks. The Internet, an international Wide Area Network, uses TCP/IP to connect government and educational institutions across the world. TCP/IP is also in widespread use on commercial and private networks. The TCP/IP suite includes the following protocols
| Data Link Layer | |
| ARP/RARP | Address Resolution Protocol/Reverse Address |
| DCAP | Data Link Switching Client Access Protocol |
Network Layer | |
| DHCP | Dynamic Host Configuration Protocol |
| DVMRP | Distance Vector Multicast Routing Protocol |
| ICMP/ICMPv6 | Internet Control Message Protocol |
| IGMP | Internet Group Management Protocol |
| IP | Internet Protocol version 4 |
| IPv6 | Internet Protocol version 6 |
| MARS | Multicast Address Resolution Server |
| PIM | Protocol Independent Multicast-Sparse Mode (PIM-SM) |
| RIP2 | Routing Information Protocol |
| RIPng for IPv6 | Routing Information Protocol for IPv6 |
| RSVP | Resource ReSerVation setup Protocol |
| VRRP | Virtual Router Redundancy Protocol |
Transport Layer | |
| ISTP | |
| Mobile IP | Mobile IP Protocol |
| RUDP | Reliable UDP |
| TALI | Transport Adapter Layer Interface |
| TCP | Transmission Control Protocol |
| UDP | User Datagram Protocol |
| Van Jacobson | compressed TCP |
| XOT | X.25 over TCP |
Session Layer | |
| BGMP | Border Gateway Multicast Protocol |
| Diameter | |
| DIS | Distributed Interactive Simulation |
| DNS | Domain Name Service |
| ISAKMP/IKE | Internet Security Association and Key Management Protocol and Internet Key Exchange Protocol |
| iSCSI | Small Computer Systems Interface |
| LDAP | Lightweight Directory Access Protocol |
| MZAP | Multicast-Scope Zone Announcement Protocol |
| NetBIOS/IP | NetBIOS/IP for TCP/IP Environment |
Application Layer | |
| COPS | Common Open Policy Service |
| FANP | Flow Attribute Notification Protocol |
| Finger | User Information Protocol |
| FTP | File Transfer Protocol |
| HTTP | Hypertext Transfer Protocol |
| IMAP4 | Internet Message Access Protocol rev 4 |
| IMPPpre/IMPPmes | Instant Messaging and Presence Protocols |
| IPDC | IP Device Control |
| IRC | ·Internet Relay Chat Protocol |
| ISAKMP | Internet Message Access Protocol version 4rev1 |
| ISP | |
| NTP | Network Time Protocol |
| POP3 | Post Office Protocol version 3 |
| Radius | Remote Authentication Dial In User Service |
| RLOGIN | Remote Login |
| RTSP | Real-time Streaming Protocol |
| SCTP | Stream Control Transmision Protocol |
| S-HTTP | Secure Hypertext Transfer Protocol |
| SLP | Service Location Protocol |
| SMTP | Simple Mail Transfer Protocol |
| SNMP | Simple Network Management Protocol |
| SOCKS | Socket Secure (Server) |
| TACACS+ | Terminal Access Controller Access Control System |
| TELNET | TCP/IP Terminal Emulation Protocol |
| TFTP | Trivial File Transfer Protocol |
| WCCP | Web Cache Coordination Protocol |
| X-Window | X Window |
Routing | |
| BGP-4 | Border Gateway Protocol |
| EGP | Exterior Gateway Protocol |
| EIGRP | Enhanced Interior Gateway Routing Protocol |
| HSRP | Cisco Hot Standby Router Protocol |
| IGRP | Interior Gateway Routing |
| NARP | NBMA Address Resolution Protocol |
| NHRP | Next Hop Resolution Protocol |
| OSPF | Open Shortest Path First |
| TRIP | Telephony Routing over IP |
Tunneling | |
| ATMP | Ascend Tunnel Management Protocol |
| L2F | The Layer 2 Forwarding Protocol |
| L2TP | Layer 2 Tunneling Protocol |
| PPTP | Point to Point Tunneling Protocol |
Security | |
| AH | Authentication Header |
| ESP | Encapsulating Security Payload |
| TLS | Transport Layer Security Protocol |
