TCP/IP stands for 'Transport Control Protocol / Internet Protocol'
or 'Internet Protocol Suite'. TCP/IP was used in 1982 as the standard
military computer networking protocol. TCP/IP was developed as a
replacement to NCP (Network Control Program); although it has evolved
from reserch conducted by DARPA and the launch of ARPANET in the
1960's. Robert E. Kahn and Vinton Cerf are credited as the "founding
fathers" of TCP/IP.
The advantage of TCP/IP is it's versitility. It can successfully
switch packets of all shapes and sizes, and works across a varieties
of networks. TCP/IP has become the backbone of the Internet and
its composite LANs and WANs. As already stated, it is due to it's
ability to switch packets from any computer systems, regardless
of network peculiarities, operating system differences, or, packet
The TCP/IP protocol suite refers to several separate protocols
that computers use to transfer data across the Internet. It is named
TCP/IP because the first two protocols included/defined in the suite
- and probably the two most important - are:
- Transmission Control Protocol (TCP)
- Internet Protocol (IP)
Listed below are four commonly used TCP/IP protocols:
Key Protocols of TCP/IP
- IP - The Internet Protocol is a network layer protocol
that moves data between host computers.
- TCP - The Transport Control Protocol is a transport layer
protocol that moves multiple packet data between applications.
- UDP - The User Datagram Protocol is a transport layer
protocol like TCP but is less complex and reliable than TCP.
- ICMP - The Internet Control Message Protocol carries
network error messages and other network software requirements.
Four Layer Model
As TCP/IP evolved, the various protocols included in the suite
have been classified into four "loosely" defined layers.
The four layers in TCP/IP are:
- Application layer: protocols used by applications designed
for users services.
- Transport layer: creates a data channel for a specific
- Internet layer: sends data(packets) across computer networks.
- Link layer: moves data between the internet layers of
Within the above layers, you can find the following protocols:
Application layer: BGP, DHCP, DNS, FTP,
HTTP, IMAP, IRC,
LDAP, MGCP, NNTP, NTP, POP, RPC, RTP, RTSP,
RIP, SIP, SMTP, SNMP, SOCKS, SSH, Telnet,
Transport layer: DCCP, RSVP, SCTP, TCP, UDP.
Internet layer: ECN, ICMP, IGMP,
Link layer: ARP, DSL, FDDI, ISDN,
NDP, OSPF, PTPP
The TCP/IP layer model was developed before the OSI model (computer
networking model); and as such, is sometimes confused for the OSI
model. The TCP/IP protocol suite is evolved/maintained by IETF
(Internet Engineering Task Force); TCP/IP is viewed as being more
"fluid" and less formal than the OSI model.