Protocols are specific rules for transferring information. Consider this example to better understand the concept: when two governments communicate, they use established protocols. This is to ensure that both sides fully understand and interpret the exact information shared. Similarly, two computer systems exchange information using common protocols.
Protocols generally describe various network services in the following ways:
- Providing formulas for passing messages
- Specifying details of message formats
- Describing how to handle error conditions
The entire Internet is governed by rules set forth by TCP/IP with other compliant standards. Similarly, the application packages that perform different services to be run on the Internet (email, ftp, remote log-in, etc) build their own protocols on the basis of TCP/IP. The following is a brief list describing important protocols used by the Internet:
Transmission Control Protocols (TCP) is a connection-oriented protocol that keeps track of data packets (individual units of the message data) for efficient routing through the Internet. TCP takes care of packet sequence in a particular message and puts data packets back in the right order.
Internet Protocols (IP) is a connectionless protocol that actually delivers the message data packets. The combination of TCP and IP establishes a method for transmitting data as well as integrity of data transmission across the Internet.
Simple Mail Transfer Protocol (SMTP) governs the transmission of electronic messages (e-mails) across the Internet. It is used with one of the two other protocols (POP3 or IMAP) to enable users to download messages from a server or save them in a server mailbox.
File Transfer Protocol (FTP) is responsible for the transfer of web page files between computers and the download of application programs and other files from other servers.
Hypertext Transfer Protocol (HTTP) lets users access hyperlinked (interconnected) web pages and related files on the Internet.
POP3 controls the storage of e-mail messages on a mail server.
Point-to-Point Protocol (PPP) dictates how the dial-up connection should be made and monitors for transmission errors.
Secure Socket Layer (SSL) is an encryption protocol that is needed to protect Web data during its transmission
Dynamic Host Configuration Protocol (DHCP) is a communications protocol that helps network administrators to centrally manage and automate the assignment of Internet Protocols (IP) addresses in an organization network environment.
Session Initiative Protocol (SIP) is used for initiating interactive user sessions involving multimedia elements such as video, voice, chat, gaming and virtual reality.
Layer two Tunneling Protocol is an extension of the Point-to-Point Tunneling Protocol used by an ISP to deliver virtual private network (VPN) services over the Internet.
Next Hop Resolution Protocol allows the computer sending data to learn the most direct route to the computer at the receiving end.
Open Trading Protocol is used as a common method of data exchange among trading and business parties -- manufacturers, distributors, retailers, and shoppers.
Internet Message Access Protocol is a standard protocol used for accessing email from a local server.
Anti-replay Protocol is employed for maintaining IP packets. With this protocol, it becomes impossible for a hacker to intercept message packets and to add changed packets into the data stream between two computers (located at source and destination points).
Common Management Information Protocol (CMIP) is a network management protocol that is built on the open systems interconnection communication model.
Voice over Internet Protocol (VOIP) is based on sending voice information in digital form in discrete packets. VOIP also uses real-time protocol (RTP) to ensure that data packets reach their destination in a timely manner.
Address Resolution Protocol (ARP) is used to map an Internet Protocol (IP) address to a physical machine address so as to make it recognizable in the local network. ARP provides protocol rules to correlate between each Machine Access Control (MAC) address and its corresponding IP address.
File Transfer Protocol (FTP) is an application protocol that uses TCP/IP to transfer Web page files and programs from one computer to another.
Link Control Protocol (LCP) is used for establishing, configuring and testing data-link internet connections in the Point-to-Point (PPP) Protocol setup. LCP checks the telephone line connection to ensure data transmission at the intended rate.
Secure Hypertext Transfer Protocol (S-HTTP) delivers secure communication mechanisms between an HTTP client-server pair. It enables spontaneous commercial transactions for various applications and operation modes.
Virtual Router Redundancy Protocol (VRRP) enables to specify a virtual IP address to be shared among routers in a local area network (LAN) in which one functions as a master router. If somehow this master router fails, the virtual IP address is mapped to the IP address of the backup router which then becomes the master router.
Simple Network Management Protocol (SNMP) governs monitoring of network devices, their functions and other areas of network management.
Lightweight Directory Access Protocol (LDAP) is a software protocol that is used to locate organizational departments, individuals and other resources (files, network devices) on a public Internet or a private Intranet.
Serial Line Internet Protocol (SLIP) is a TCP/IP protocol. It lets two machines talk to each other that are previously configured for communications.
Trivial File Transfer Protocol (TFTP) is used for transferring files where user authentication and directory vulnerability are not required. TFTP is simple to use but is less capable then the File Transfer Protocol (FTP).
Enhanced Interior Gateway Routing Protocol (EIGPR) lets routers exchange information more efficiently. It uses diffusing Update Alogrithm (DUAL) to determine the most efficient route to a particular destination.
Border Gateway Protocol is used between gateway hosts on the Internet for the purpose of exchanging routing information in a network of autonomous systems.
Server Messages Block Protocol (SMB) lets application users access remote server files and other resources (to read, create, and update files on the remote server).