Radia Joy Perlman (born December 18, 1951) is an American computer programmer and network engineer. She played a key role in developing the technology that makes the Internet possible. She is best known for creating the Spanning Tree Protocol (STP), which helps network bridges function properly. She earned this nickname, "Mother of the Internet," while working for Digital Equipment Corporation. Her work has greatly influenced how networks organize themselves and share data. She also made important contributions to other areas of network design, such as improving link-state routing protocols to be more reliable, larger in scale, and easier to manage.

In 2019, Perlman was elected to the National Academy of Engineering for her work on Internet routing and bridging protocols. She has over 100 patents. She was inducted into the Internet Hall of Fame in 2014 and the National Inventors Hall of Fame in 2016. She received lifetime achievement awards from USENIX in 2006 and from the Association for Computing Machinery’s SIGCOMM in 2010.

More recently, she developed the TRILL protocol to address some limitations of spanning trees, allowing Ethernet networks to use bandwidth more efficiently. As of 2022, she was a Fellow at Dell Technologies.

Early life

Perlman was born in 1951 in Portsmouth, Virginia. She grew up in Loch Arbour, New Jersey. She is Jewish. Both of her parents worked as engineers for the US government. Her father worked on radar, and her mother was a mathematician who later became a computer programmer. During school, Perlman found math and science to be easy and interesting. She also earned top grades in other subjects, even though she was very careful about doing everything perfectly. She enjoyed playing the piano and the French horn. While her mother helped her with math homework, they mostly talked about books and music. However, Perlman did not feel she matched the image of an "engineer," because she never took apart or put together computer parts.

Although she was the best student in science and math at her school, Perlman only began thinking about a career involving computers after taking a programming class in high school. She was the only girl in the class. Later, she said, "I was not a hands-on person. I never thought about taking things apart. I worried I might get hurt or break something." She graduated from Ocean Township High School in 1969.

Education

As an undergraduate student at MIT, Perlman learned programming for a physics class. In 1971, she received her first paid job as a part-time computer programmer for the LOGO Lab at the (then) MIT Artificial Intelligence Laboratory. She worked on system software, such as tools used to find and fix errors in programs.

Under the guidance of Seymour Papert, Perlman created a version of the LOGO programming language designed for young children. This version was named TORTIS, which stands for "Toddler's Own Recursive Turtle Interpreter System." Between 1974 and 1976, research showed that very young children, as young as 3 years and 6 months, could use a LOGO robot named a Turtle to write simple programs. Experts later described Perlman as a pioneer in teaching young children how to program computers. After this work, she wanted to create a new programming language for even younger children, using special keyboards and input devices. However, she stopped the project because she felt she needed to be taken seriously as a scientist and was uncomfortable with the focus on young children. Later, a project at MIT Media discovered her work and noted that her abandoned idea helped inspire a new field called tangible user interface.

As a mathematics graduate student at MIT, Perlman needed an advisor for her thesis and joined the MIT team at BBN Technologies. There, she began working on designing network protocols. She earned a bachelor’s degree and master’s degree in mathematics, and later completed a PhD in computer science from MIT in 1988. Her PhD research focused on how to route data in networks where problems could happen on purpose. This work became the foundation for many modern studies in this area.

When Perlman studied at MIT in the late 1960s, she was one of about 50 women in a class of around 1,000 undergraduate students. At first, MIT had only one dormitory for women, which limited the number of female students. When men’s dorms at MIT became coed, Perlman moved to a mixed-gender dorm and became the "resident female" on that floor. She later said that she became so accustomed to the small number of women in her classes that it felt normal. However, she noticed that it seemed unusual when she saw other women among a group of men.

Career

After graduating, she began working for Bolt, Beranek, and Newman (BBN), a company that created software for network equipment. While at BBN, she impressed a manager from Digital Equipment Corporation (DEC), who offered her a job. She joined DEC in 1980. During her time there, she developed the Spanning Tree Protocol (STP), which helps networks send data reliably. STP allows networks to use extra connections that can be used if needed. If one connection fails, the network automatically switches to another. This setup ensures only one active path exists between any two points in the network. STP is important for network bridges in smaller networks. She wrote a textbook called Interconnections: Bridges, Routers, Switches, and Internetworking Protocols and coauthored another on network security, Network Security: Private Communication in a Public World, which is now a popular college textbook. Her work in network security includes methods for managing trust in systems that use public keys, ways to limit data access, and algorithms that work even if some parts are not trustworthy.

She left DEC in 1993 and joined Novell. In 1997, she moved to Sun Microsystems. Over her career, she earned more than 200 patents, 40 while working at Sun Microsystems, where she held the title of Sun Fellow. She taught classes at the University of Washington, Harvard University, MIT, and Texas A&M, and gave speeches at events worldwide. She has received awards such as Lifetime Achievement awards from USENIX and the Association for Computing Machinery’s Special Interest Group on Data Communication (SIGCOMM).

Perlman created the spanning tree algorithm and protocol. While working as a consulting engineer at DEC in 1984, she was asked to develop a simple protocol that helped network bridges find loops in a local area network (LAN). The protocol needed to use the same amount of memory on all devices, no matter how large the network was. Building networks was difficult because loops—extra paths that could lead to the same place—could cause the network to stop working. Extra paths could make bridges send data in multiple directions, which could stop data from reaching its destination and flood the network.

Perlman used the fact that bridges have unique 48-bit MAC addresses to create a protocol that let bridges in the LAN communicate with each other. The algorithm on all bridges allowed them to choose one root bridge in the network. Each bridge then mapped the network and found the shortest path to the root bridge, turning off other extra paths.

Although Perlman worried that STP took about a minute to adjust when network changes happened, which could cause loops to stop the network, it was later standardized as 802.1d by the Institute of Electrical and Electronics Engineers (IEEE). Perlman said the protocol’s benefit is that users do not need to worry about network changes. However, she criticized some changes made during the standardization process.

Perlman wrote a poem about STP called Algorhyme:

— Radia Perlman, Algorhyme

She was the main designer of the DECnet IV and V protocols and IS-IS, the OSI version of OSPF. She also contributed to the Connectionless Network Protocol (CLNP). She worked with Yakov Rekhter to develop network routing standards, such as the OSI Inter-Domain Routing Protocol (IDRP), the OSI version of BGP. At DEC, she helped switch from distance vector to link-state routing protocols. Link-state protocols adapted faster to network changes, and DEC’s protocol was second only to the one used in the Advanced Research Projects Agency Network (ARPANET). While working on DECnet, she improved the IS-IS protocol so it could handle Internet Protocol (IP), AppleTalk, and Internetwork Packet Exchange (IPX). The Open Shortest Path First (OSPF) protocol used some of her research on sending routing information reliably.

She later worked as a network engineer for Sun Microsystems, now Oracle. She focused on network and security protocols and earned more than 50 patents while working at Oracle.

When standardizing TRILL, a protocol that combines bridging and routing to replace STP, she included a second version of her poem Algorhyme. Algorhyme V2 is credited to Ray Perlner, one of the coauthors of Network Security: Private Communication in a Public World (3rd ed):

— Ray Perlner, Algorhyme V2, RFC 6325

Awards

• Member of the Association for Computing Machinery, class of 2016
• Inducted into the National Inventors Hall of Fame in 2016
• Inducted into the Internet Hall of Fame in 2014
• Received the SIGCOMM Award in 2010
• Named an IEEE Fellow in 2008 for work in network routing and security protocols
• Received the USENIX Lifetime Achievement Award in 2006
• Received the first Anita Borg Institute Women of Vision Award for Innovation in 2005
• Named Inventor of the Year by the Silicon Valley Intellectual Property Law Association in 2003
• Received an honorary Doctorate from the Royal Institute of Technology on June 28, 2000
• Named among the 20 most influential people in the industry twice by Data Communications magazine: in the 20th anniversary issue on January 15, 1992, and the 25th anniversary issue on January 15, 1997. Perlman is the only person named in both issues.