Internet (TCP/IP) protocol family

The TCP/IP family of protocols is widely used today.

Specifications of all of these protocols can be found in the RFC documents.

A simplified overview of the core TCP/IP protocols could look like this:

5-7 Application layer (HTTP, FTP, …)
4 TCP (connections) / UDP (connectionless)
3 Internet (IP, ICMP)
2 Link layer (ARP, PPP, Ethernet, …)


The TCP/IP family consists of (at least) the following protocols:

Link layer:

  • ARP: Address Resolution Protocol: Map IP to hardware (e.g. Ethernet) addresses

  • RARP: Reverse ARP: Map hardware (e.g. Ethernet) to IP addresses

Link layer (serial line):

  • CSLIP: Compressed Serial Line IP: Compressing TCP/IP Headers for Low-Speed Serial Links RFC 1144, obsolete

  • PPP: The Point-to-Point Protocol

  • PPP-MP: The Point-to-Point Multilink Protocol

  • SLIP: Serial Line IP: Transmission of IP datagrams over serial lines RFC 1055, obsolete

Network layer:

  • IP: Internet Protocol (version 4): transfer IP packets from one host to another. One of the most common protocols today. This is what the Internet is built around.

  • IPv6: Internet Protocol (version 6): transfer IP packets from one host to another

  • ICMP: Internet Control Message Protocol (version 4): This is a protocol to report common errors and events in the IP, TCP and UDP protocols.

  • ICMPv6: Internet Control Message Protocol (version 6): This is a protocol to report common errors and events in the IPv6, TCP and UDP protocols.

  • IGMP: IP multicasting

Network layer (routing):

  • BGP: Border Gateway Protocol

  • EGP: Exterior Gateway Protocol

  • GGP: Gateway to Gateway Protocol

  • IGRP: Interior Gateway Routing Protocol

  • ND: Neighbor Discovery

  • OSPF: Open Shortest Path First

  • RIP: Routing Information Protocol

  • RIPng: Routing Information Protocol next generation

  • DSR: Dynamic Source Routing (Ad-hoc protocol)

Network Layer (IPsec Internet Protocol Security):

  • AH: Authentication Header

  • ESP: Encapsulating Security Payload

Transport layer:

  • These protocols run atop IP:

  • DCCP: Datagram Congestion Control Protocol: stream based, reliable, connection oriented transfer of data

  • SCTP: datagram (packet) based, reliable, connection oriented transfer of data

  • UDP: User Datagram Protocol: datagram (packet) based, unreliable, connectionless transfer of data

  • UDP-Lite: Lightweight User Datagram Protocol: datagram (packet) based, unreliable, connectionless transfer of data

  • TCP: Transmission Control Protocol: stream based, reliable, connection oriented transfer of data

  • PortReference: TCP/UDP port numbers

These protocols run atop UDP, and provide additional transport-layer services:

  • RTP: datagram (packet) based, unreliable, connection oriented transfer of time sensitive data

  • RTCP: RTP's control protocol

Session layer:

  • NetBIOS: an API and several protocols providing various networking services.

  • NetDump: a simple protocol for capturing crashed operating system memory cores over a network

  • ONC-RPC: Remote procedure calls using Sun's RPC mechanism

  • DCE/RPC: Remote procedure calls using the OSF's RPC mechanism

  • HTTP: Hyper Text Transfer Protocol: (and other files as well). Probably the best known protocol as it is used to allow users surfing on the Internet.

  • SMTP: Simple Mail Transfer Protocol: send mails to a mail server

Presentation layer:

  • MIME: content encoding (for HTTP, SMTP, …) (RFC 2045-2049)

Application layer:

  • ANCP: Access Node Control Protocol: TCP based L2 control protocol used in service provider DSL and PON Networks.

  • BOOTP: BOOT Protocol: antecessor of DHCP, see below

  • DHCP: Dynamic Host Configuration Protocol: distribute IP, Gateway and DNS server addresses and alike

  • DNS: Domain Name System: translate human readable addresses (e.g. into IP addresses

  • FTP: File Transfer Protocol: file transfer (unsecure)

  • IMAP: retrieve mails from a mail server

  • iWARP-DDP: Direct Data Placement (part of the iWARP protocol stack)

  • iWARP-MPA: Marker PDU Aligned Framing: adaptation layer between TCP and DDP (part of the iWARP protocol stack)

  • iWARP-RDMAP: Remote Direct Memory Access Protocol (part of the iWARP protocol stack)

  • NNTP: Network News Transfer Protocol: news transfer

  • NTP: Network Time Protocol: sychronize time between hosts

  • PANA: Protocol for Carrying Authentication for Network Access: user authentication for network access

  • POP: Post Office Protocol: receive mails from a mail server

  • RADIUS: remote user authentication and accounting

  • RLogin: remote login: remote shell access (unsecure)

  • RSH: Remote SHell: remote shell access (unsecure)

  • RSIP: Realm Specific IP (RFC 3102-3104)

  • SSH: Secure SHell: encrypted remote shell access

  • SNMP: Simple Network Management Protocol: network management (RFC 1157,1901-10,2271-75)

  • Telnet: remote shell access (unsecure) (RFC 854,855,1700)

  • TFTP: Trivial File Transfer

  • SASP: Server/Application State Protocol (RFC 4678)


  • URN: Uniform Resource Names (RFC 1737)

  • URL: Uniform Resource Locators (RFC 1738)


XXX - add a brief description of TCP/IP history?


  • "Internetworking With TCP/IP Volume 1: Principles Protocols, and Architecture" from Douglas Comer (5th edition, 2006. ISBN 0-13-187671-6)
  • "TCP/IP Illustrated, Volume 1: The Protocols" from W. Richard Stevens (Addison-Wesley, 1994, ISBN 0-201-63346-9.)

External links

  • "The TCP/IP Guide" from Charles M. Kozierok, printed book (1600 pages!), also available for online reading


  • contrary to common belief: HTTP is not an application protocol, is a session (L5) protocol, uses MIME for presentation (L6), and, the application (L7) in this case is a wiki! (another example is HTTP/XML/SOAP). (On the other hand, if you click on a download link, you're using HTTP for file transfer, so, in that case, it's an application-layer protocol. Protocols can't necessarily always be assigned to one and only one layer of the 7-layer model. -Guy Harris)

  • Does DCE/RPC and/or ONC/RPC really belong to the Internet Protocol Family? I wouldn't search at least DCE/RPC here. - Ulf Lamping ONC RPC was, at least at one time, supported on the OSI transport protocols as well (Connectathon included ONC RPC-over-OSI testing), so if this page is to hold protocols that only run atop Internet transport protocols, neither of them would belong here. There are a lot of protocols that run directly or indirectly atop the Internet transport protocols, so the question is which of them should be listed here? -Guy Harris Difficult, but we shouldn't put all protocols at this page which runs on top of IP/TCP/UDP, that would just be too much. I would think of this family as the protocols "when I hear the abbreviation, I would immediately think of looking at the RFC's" - simply speaking. But that will be a step-by-step decision. For the DCE/RPC I would think of a whole new family, namely the protocol itself plus all the interfaces "MS protocols" using it. Don't know ONC RPC well enough if it's the case there too. - UlfLamping

Imported from on 2020-08-11 23:15:07 UTC