1977

Internetworking

SRI's packet-radio van completes the landmark three-network TCP demonstration

Sender and receiver were both in California. Their packets crossed the Atlantic and came back before arriving, and the crucial node was a van driving around the Bay Area.

The long way to Marina del Rey

On 22 November 1977 an SRI mobile packet-radio van cruising San Francisco Bay Area roads exchanged data with a host at USC's Information Sciences Institute in Marina del Rey, by a deliberately circuitous route.

Packets left the van over PRNET, passed through a gateway into ARPANET, crossed the Atlantic through links involving Norway and University College London, returned over SATNET, re-entered ARPANET and reached USC/ISI. Three dissimilar packet networks were made to behave as one internetwork, with four logical traversals because ARPANET was used twice.

What was in the van

The van carried an LSI-11 minicomputer running TCP, packet radios and a terminal. Jim Mathis drove it; Virginia Strazisar at BBN had developed and monitored the gateway software that moved traffic between unlike networks, and Peter Kirstein's UCL team handled the European leg.

Robert Kahn had framed the problem — joining packet-radio, satellite and wired networks without making them share an internal technology — and Vinton Cerf coordinated the implementation and testing of the protocol they designed together.

Two numbers the old title gets wrong

The test joined three networks, not three ARPANET nodes. The often-repeated figure of 111 is a March 1977 host count; a primary ARPANET completion report lists 58 switching nodes as of July 1977.

“TCP/IP test” is retrospective shorthand too. Contemporary documentation calls the protocol TCP; the clean split into IP and a host-to-host TCP was documented during 1978, and ARPANET did not convert network-wide until 1983.

Cerf later recalled an earliest demonstration of the triple-network internet in July 1977, which may refer to an earlier trial than the coordinated November run.

Sources

Researched 23 Aug 2026 9 sources 2 audit passes Date disputed

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

Date disputed. Sources disagree; the research places it at 1977-11-22.

What the sources leave uncertain

SRI's technical history and the Computer History Museum date the landmark coordinated three-network run to November 22, 1977.
Vint Cerf later recalled an 'earliest demonstration of the triple network Internet' in July 1977. This may refer to an earlier trial rather than the coordinated November demonstration, but it prevents an unqualified claim that November 22 was the first test of any kind.
Contemporary documentation calls the protocol TCP. Later accounts often call it TCP/IP because the 1977 TCP contained functions subsequently divided between TCP and IP.
Calling this single run 'the birth of the Internet' is an interpretation. The protocol and network evolved through multiple demonstrations, revisions and the 1983 ARPANET conversion.