TCP/IP Version 1.0

TCP/IP originated out of ARPANET. ARPANET was the world's first packet-switched network. That means that instead of two users communicating via a dedicated line (circuit-switched), the information sent and received is broken into smaller pieces, called packets, and sent over an interconnect. These smaller packets can be interleaved among transmissions, allowing multiple users to share the same interconnect.

Each local network connected to ARPANET through an Interface Message Processor, or IMP. Originally, there were 4 IMPs: University of California Los Angeles, Stanford Research Institute, University of California Santa Barbara, and University of Utah. The first message transmitted was "lo", from "login", before the system crashed.

Packet Features

ARPANET utilized a store-and-forward protocol. Source and Destination IMPs were specified with 16-bit addresses. If a source and destination IMP were not directly connected, their communication would be forwarded through an intermediary IMP. Since multiple paths existed, the packet required a Numbering Scheme to ensure proper reordering at the destination. Likewise, since intermediary IMPs may go down during communication, the Acknowledgement field allows a receiving IMP to reply an acknowledge receipt of a message. The 16-bit Checksum field allowed the destination IMP to verify that the packet arrived without errors.

TCP/IP Version 2.0

Time Machine Jet Lag Updates

• Ethernet developed at Xerox PARC, 1973-1974

• UNIX released to the outside world, 1975

• John Vittal released a modern email client, 1975

• Satellite links used to connect nodes across oceans (Hawaii and UK), 1975

• Unix-to-Unix CoPy (UUCP) created to copy files between UNIX installs, 1976

• X.25 packet-switching service protocols finalized, 1976

Packet Features

Version 2 of TCP/IP includes many new features. First, an Options field was added to allow for special features such as diagnostic timestamping, security, priorities, etc. The error messages from v1 were eliminated, except for the Reset flag. Port fields for the Source and Destination were added to accomodate nodes that accept multiple connections. The TCP identifier consisted of the Network (8-bits) and Host (24-bits) address plus the process' port address (24-bits).

In order to close a connection, the FIN signals must also be acknowledged, which was not the case in version 1. Also, INT and FIN no longer cause data-stream flushing, however this version does not include a FLUSH command. Finally, reassembling fragments into segments was fully specified and a method for dealing with flow-control windows that have gone to zero was provided.

TCP/IP Version 3.0

Time Machine Jet Lag Updates

• Dennis Hayes created 300 bit/s modem, April 1977

• DARPA created wireless packet radio network PRNET, connecting to ARPANET at 100-400 kbps, 1977

Packet Features

TCP/IP was formally split into two separate packet headers for version 3. Many changes have been specified:

• INT interrupt signal has been eliminated for an Urgent Pointer.

• Resynchronization mechanisms eliminated for a quiet period on the initialization of TCP.

TCP Version 3.1

Packet Features

This new version, following a month after the previous, addressed a few important changes. They were:

• Port addressing moved from TCP header to IP header.

• TCP no longer handles fragmentation. That will be addressed in the Internet layer.

Many changes to fix the size of the packet and slim the packet to end on a 32-bit boundary were included as well. The Urgent Pointer is always present, but ignored if the URG control flag is not set. Control and data offset fields have been resized and combined to one 16-bit segment. The Checksum field provides a checksum of the TCP header, options, and test.

TCP Version 4.0

Time Machine Jet Lag Updates

• First commercial spam message sent, May 1978

Version Updates

In this version, all addressing information has been removed from the TCP header. It is provided by the Internet layer, as shown in the IP header. Likewise, fragmentation and reassembly have also moved from the TCP header to the Internet protocols.

Network Setup

The anticipated layered network setup is outlined with the description of TCP Version 4.0. TCP now supports higher-level protocols such as Telnet and FTP (originally written for ARPANET) and expects levels of service to be guaranteed by the Internet Protocol (a lower-level protocol). This setup is how the current Internet works.

Protocol Relationships (Updated to show current high-level protocols)

TCP Version 4.0 (Revised)

Revisions

The inner-workings of TCP were modified to now require a lower-level protocol (Internet Layer), which will fully implement the ARPA Internetwork Protocol. All addressing, fragmentation, and reassembly must be performed by this lower layer.

TCP Version 4.0 (Revised)

Time Machine Jet Lag Updates

• Usenet created, with connection between Duke and UNC, 1979

Revised Features

The February 1979 update to TCP specified the behavior of the protocol, without changing the packet designs. The Protocol is formally layered between applications (higher-level) and Internet datagram protocol (lower-level), as pictured below.

Protocol Layers (updated to show current protocols)

IP Version 4.0 (Revised)

Time Machine Jet Lag Updates

• Discussions between DARPA, NSF, and University of Wisconsin to establish a Computer Science research network, 1979

• DARPA established the Internet Configuration Control Board, 1979

Packet Updates

The Source and Destination addressing schemes were updated in IPv4. The Type of Service flags in the Internet Protocol were also formally specified allowing for 4 levels of priority as well as settings for either speed or reliability.

NO CHANGE: TCP Version 4.0 (Revised)

What happened while in the DeLorean

Changes to network structure will go here. Changes in the packet designs. TCP and IP are now split into their own headers, as defined by separate specifications.

Packet Features

Packet features will be here

NO CHANGE: TCP Version 4.0 (Revised)

What happened while in the DeLorean

Changes to network structure will go here. Changes in the packet designs. TCP and IP are now split into their own headers, as defined by separate specifications.

Packet Features

Packet features will be here

TCP Version 4.0 / IP Version 4.0 (Revised)

Time Machine Jet Lag Updates

• Usenet connected to ARPANET by UC Berkeley, 1980

• IEEE started project 802 to standardize Local Area Networks, 1980

• DIX Ethernet (10 Mbps) standard released (48-bit destination and source MAC addresses), 1980

• Ethernet II standard released, 1981

• Ethernet links used shared coaxial cable (10BASE5) resulting in high collisions, early 1980s

Version Notes

This is the last fully specified version of Internet Protocol Version 4.

IP Version 6.0

Time Machine Jet Lag Update

Much has happened in the last 17 years while you were waiting for a packet update:

• IEEE 802.3 standard for LANs approved, 1982

• All ARPANET computers switched over to TCP/IP, 1983

• The Domain Name System for resolving names to IP addresses was created, 1984

• U.S. Federal Communications Commission releases ISM radio band for unlicensed use (802.11), 1985

• NSFNET (56 Kbps) backbone created, 1986

• Twisted-pair Ethernet 802.3e developed (10BASE-T) to reduce and eventually eliminate collisions (1 Mbps), 1986

• 10BASE-T Ethernet 802.3i updated to 10 Mbps, 1987

• NSFNET updated to T1 (1.54 Mbps) connection, 1988

• The World Wide Web (Berners-Lee) proposed, 1989

• Death of ARPANET, 1990

• Commercialization and explosion of the Internet (commercial dial-up connections, web sites, etc), 1990 - 1998

• NCR Corporation / AT&T develop wireless communication standard IEEE 802.11, 1991

• NSFNET de-commercializes, all commercial traffic handed to interconnected service providers, 1995

• 100BASE-TX Ethernet 802.3u updated to 100 Mbps, 1995

• Perkins in RFC 2003 proposed a method for Internet Datagram (IPv4) packets to be encapsulated within other IPv4 packet headers to be carried on other types of networks. For example, a packet could be routed over a Mobile IP network. This method was suggested as a way to facilitate or replace normal IPv4 routing. 1996

IP Version 6.0 Features

There were five major changes introduced in IPv6 to address shortcomings of IPv4 in 1998:

• Source and Destination Addresses were increased from 32-bits to 128-bits to support a larger address hierarchy, allow for more addresses, and provide mechanism for auto-configuration of device addresses.

• Simplified the fields in the header by creating optional headers, which may be left out if unnecessary.

• Improved support for specifying and adding Options to the IP header.

• Flow labels, so that each packet may be classified into a level-of-service flow. This is controversial, since it allows headers to have various quality of service definitions.

• Extensions to support authentication, data integrity, and confidentiality.

Notes

IPv6, even though defined over a decade ago, is still not widely used in the Internet. Network Address Translation (NAT) provided a buffer for the small 32-bit address space, allowing IPv4 to continue without enough true addresses available.

IP Version 4.0 (Revised)

Time Machine Jet Lag Update

• IPv4 is still supported, since IPv6 has not gained enough support since 1998

• 1000BASE-T Ethernet 802.3ab updated to 1 Gbps, 1999

• Wireless 802.11b released supporting speeds up to 11 Mbps, 1999

• Wireless 802.11a released supporting speeds up to 54 Mbps, 1999

• Wireless 802.11g released supporting speeds up to 54 Mbps, 2003

• 10GBASE-T Ethernet 802.3an updated to 10 Gbps, 2006

• Wireless 802.11n released supporting speeds up to 150 Mbps, 2009

• Draft of wireless 802.11ac released supporting speeds up to 867 Mbps, 2012

• Anticipated wireless 802.11ad proposed to support transmission speeds up to 7 Gbps, 2014

Updates Featured

This update focus on the Identification field of IPv4. This problem does not exist in IPv6, but must be fixed in IPv4. The Identification field must be unique for each packet, based on Source, Destination, and Protocol for a given maximum datagram lifetime (MDL). Since this field is only 16-bits and the MDL was set at 2 minutes, this limited the maximum throughput of any link to 6.4 Mbps. To address this problem, RFC 6864 updates the IPv4 Identification field to be used only when a datagram is fragmented, similar to how that field is used in IPv6.