Radia Perlman

Radia Perlman grew up in Loch Arbour, New Jersey, watching her mother, a mathematician, work as a computer programmer at a time when almost nobody thought to call that a woman's job, since her father designed radar systems for the government. She learned to program almost by accident, picking it up for a physics class, and enrolled at MIT in the late 1960s as one of roughly fifty women in an incoming class of a thousand. She earned bachelor's and master's degrees in mathematics there, then took her first paid programming job in 1971 at the lab where Seymour Papert was building LOGO, writing debugger software and, at his request, adapting the language for children as young as three and a half.

At Digital Equipment Corporation in 1984, working as a consulting engineer, Perlman solved a problem that threatened to make large computer networks unusable: redundant cabling meant to provide backup paths could instead trap data in endless loops, flooding and crippling a network. Her spanning tree algorithm let network bridges talk to each other, agree on a single active path between any two points, and hold the rest in reserve, using a fixed amount of memory no matter how large the network grew. She wrote the whole specification as a poem, "Algorhyme," rather than a memo. The protocol became the international standard IEEE 802.1d and, for two decades, the invisible reason large office and campus networks did not collapse under their own wiring, though she went on to design DECnet, IS-IS and other routing protocols she considers more elegant.

Perlman built her name on a piece of software she now considers a mistake worth correcting. Spanning tree's one flaw was speed: a network took roughly a minute to reroute around a failure, an eternity by internet standards, and standards bodies modified her original design in ways she argued made it worse rather than better. Decades later she designed TRILL specifically to replace it. She has also spent much of her public life fighting the title the industry gave her, "Mother of the Internet," a label she calls oversimplified and says she actively dislikes, pointing out that she designed protocols for local networks, not the internet's core routing, and that crediting one person for something thousands of engineers built obscures how the work actually happened.

Now in her seventies, Perlman holds a Fellow title at Dell Technologies, more than two hundred patents to her name, and a stack of honors that includes the Internet Hall of Fame, the National Inventors Hall of Fame, the National Academy of Engineering, and IEEE and ACM fellowships. She still teaches occasionally at MIT, Harvard and the University of Washington, and her 1999 networking textbook remains standard reading in computer science programs decades after publication. The TORTIS programming environment she built for preschoolers at MIT, meant to make computing tangible for children too young to type, is now cited by researchers as an early ancestor of the physical-computing interfaces built for classrooms today.

Radia Perlman's life against the full span of the corpus — the fading end marks a life still in progress.

• TORTIS invention
  Child-friendly LOGO variant built at Seymour Papert's MIT lab 1976
• Spanning Tree Protocol invention
  Let network bridges eliminate loops; standardized as IEEE 802.1d 1984
• Algorhyme other
  The protocol's own specification, written as a poem 1985
• TRILL protocol invention
  Designed to replace spanning tree's slow reconvergence 2004
• Interconnections: Bridges, Routers, Switches, and Internetworking Protocols book
  Standard networking textbook, still used decades later 1999

• December 18, 1951 aged 0 Born in Portsmouth, Virginia
• 1969 aged ~18 Graduates Ocean Township High School and enrolls at MIT
• 1971 aged ~20 Takes her first programming job at MIT's LOGO Lab
• 1980 aged ~29 Joins Digital Equipment Corporation
• 1984 aged ~33 Develops the spanning tree algorithm
• 1988 aged ~37 Earns her Ph.D. in computer science from MIT
• 1999 aged ~48 Publishes Interconnections
• 2014 aged ~63 Inducted into the Internet Hall of Fame

• Vint Cerf b. 1943
  Co-designer of the TCP/IP protocols that form the foundation of the internet. fellow Internet Hall of Fame inductee
• Bob Kahn b. 1938
  Co-inventor of the TCP/IP protocols alongside Vint Cerf, enabling modern digital communication. parallel architect of internet infrastructure
• Tim Berners-Lee b. 1955
  British-American computer scientist who invented the World Wide Web, revolutionizing global information sharing. built the web her protocols carried