|Born||1951 (age 67–68)|
|Known for||Network and security protocols; computer books|
|Thesis||Network layer protocols with Byzantine robustness (1988)|
|Doctoral advisor||David D. Clark|
Radia Joy Perlman (born 1951) is an American computer programmer and network engineer. She is most famous for her invention of the spanning-tree protocol (STP), which is fundamental to the operation of network bridges, while working for Digital Equipment Corporation. She also made large contributions to many other areas of network design and standardization, such as link-state routing protocols.
Digital Equipment Corporation, using the trademark Digital, was a major American company in the computer industry from the 1950s to the 1990s.
Link-state routing protocols are one of the two main classes of routing protocols used in packet switching networks for computer communications, the other being distance-vector routing protocols. Examples of link-state routing protocols include Open Shortest Path First (OSPF) and Intermediate System to Intermediate System (IS-IS).
More recently she has invented the TRILL protocol to correct some of the shortcomings of spanning-trees. She is currently employed by Dell EMC.
Dell EMC is an American multinational corporation headquartered in Hopkinton, Massachusetts, United States. Dell EMC sells data storage, information security, virtualization, analytics, cloud computing and other products and services that enable organizations to store, manage, protect, and analyze data. Dell EMC's target markets include large companies and small- and medium-sized businesses across various vertical markets. The company's stock was added to the New York Stock Exchange on April 6, 1986, and was also listed on the S&P 500 index.
Perlman grew up near Asbury Park, New Jersey. Both of her parents worked as engineers for the US government. Her father worked on radar and her mother was a mathematician by training who worked as a computer programmer. During her school years Perlman found math and science to be “effortless and fascinating”, but had no problem achieving top grades in other subjects as well. She enjoyed playing the piano and French horn. While her mother helped her with her math homework, they mainly talked about literature and music.
New Jersey is a state in the Mid-Atlantic region of the United States. It is a peninsula, bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware River and Pennsylvania; and on the southwest by the Delaware Bay and Delaware. New Jersey is the fourth-smallest state by area but the 11th-most populous, with 9 million residents as of 2017, making it the most densely populated of the 50 U.S. states with its biggest city being Newark. New Jersey lies completely within the combined statistical areas of New York City and Philadelphia. New Jersey was the second-wealthiest U.S. state by median household income as of 2017.
Engineers, as practitioners of engineering, are professionals who invent, design, analyze, build, and test machines, systems, structures and materials to fulfill objectives and requirements while considering the limitations imposed by practicality, regulation, safety, and cost. The word engineer is derived from the Latin words ingeniare and ingenium ("cleverness"). The foundational qualifications of an engineer typically include a four-year bachelor's degree in an engineering discipline, or in some jurisdictions, a master's degree in an engineering discipline plus four to six years of peer-reviewed professional practice and passage of engineering board examinations.
Radar is a detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna and a receiver and processor to determine properties of the object(s). Radio waves from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed.
Despite being the best science and math student in her school it was only when Perlman took a programming class in high school that she started to consider a career that involved computers. She was the only woman in the class and later reflected "I was not a hands-on type person. It never occurred to me to take anything apart. I assumed I'd either get electrocuted, or I'd break something".
As an undergraduate at MIT Perlman learned programming for a physics class. She was given her first paid job in 1971 as part-time programmer for the LOGO Lab at the (then) MIT Artificial Intelligence Laboratory, programming system software such as debuggers.
The Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts. The Institute is a land-grant, sea-grant, and space-grant university, with an urban campus that extends more than a mile (1.6 km) alongside the Charles River. The Institute also encompasses a number of major off-campus facilities such as the MIT Lincoln Laboratory, the Bates Center, and the Haystack Observatory, as well as affiliated laboratories such as the Broad and Whitehead Institutes. Founded in 1861 in response to the increasing industrialization of the United States, MIT adopted a European polytechnic university model and stressed laboratory instruction in applied science and engineering. It has since played a key role in the development of many aspects of modern science, engineering, mathematics, and technology, and is widely known for its innovation and academic strength, making it one of the most prestigious institutions of higher learning in the world.
Logo is an educational programming language, designed in 1967 by Wally Feurzeig, Seymour Papert, and Cynthia Solomon. Logo is not an acronym: the name was coined by Feurzeig while he was at Bolt, Beranek and Newman, and derives from the Greek logos, meaning word or thought.
System software is software designed to provide a platform for other software. Examples of system software include operating systems like macOS, Ubuntu and Microsoft Windows, computational science software, game engines, industrial automation, and software as a service applications.
Working under the supervision of Seymour Papert, she developed a child-friendly version of the educational robotics language LOGO, called TORTIS ("Toddler's Own Recursive Turtle Interpreter System"). During research performed in 1974–76, young children—the youngest aged 3½ years, programmed a LOGO educational robot called a Turtle. Perlman has been described as a pioneer of teaching young children computer programming.
Seymour Aubrey Papert was a South African-born American mathematician, computer scientist, and educator, who spent most of his career teaching and researching at MIT. He was one of the pioneers of artificial intelligence, and of the constructionist movement in education. He was co-inventor, with Wally Feurzeig and Cynthia Solomon, of the Logo programming language.
As a math grad at MIT she needed to find an adviser for her thesis, and joined the MIT group at BBN Technologies. There she first got involved with designing network protocols.Perlman obtained a B.S. and M.S. in Mathematics and a Ph.D. in Computer Science from MIT in 1988. Her doctoral thesis at MIT addressed the issue of routing in the presence of malicious network failures.
When studying at MIT in the late 60s she was one among the 50 or so women students, in a class of about 1,000 students. To begin with MIT only had one women’s dorm, limiting the number of women students that could study. When the men’s dorms at MIT became coed Perlman moved out of the women’s dorm into a mixed dorm, where she became the "resident female". She later said that she was so used to the gender imbalance, that it became normal. Only when she saw other women students among a crowd of men she noticed that "it kind of looked weird".
She is most famous for her invention of the Spanning Tree Protocol (STP), which is fundamental to the operation of network bridges, while working for Digital Equipment Corporation. Perlman is the author of a textbook on networking and coauthor of another on network security. She holds more than 100 issued patents.She was a Fellow at Sun Microsystems and has taught courses at the University of Washington, Harvard University and MIT, and has been the keynote speaker at events all over the world. Perlman is the recipient of awards such as Lifetime Achievement awards from Usenix and the Association for Computing Machinery’s Special Interest Group on Data Communication (SIGCOMM).
Perlman invented the spanning tree algorithm and the Spanning Tree Protocol (STP). While working as a consulting engineer at Digital Equipment Corporation (DEC) in 1984 she was tasked with developing a straightforward protocol which enabled network bridges to locate loops in a local area network (LAN). It was required that the protocol should use a constant amount of memory when implemented on the network devices, regardless of how large the network was. Building and expanding bridged networks was difficult because loops, where more than one path leads to the same destination, could result in the collapse of the network. Redundant paths in the network meant that a bridge could forward a frame in multiple directions. Therefore loops could cause Ethernet frames to fail to reach their destination, thus flooding the network. Perlman utilised the fact that bridges had unique 48 bit MAC addresses, and devised a network protocol so that bridges within the LAN communicated with one another. The algorithm implemented on all bridges in the network allowed the bridges to designate one root bridge in the network. Each bridge then mapped the network and determined the shortest path to the root bridge, deactivating other redundant paths. Despite Perlman's concerns that it took the spanning tree protocol about a minute to react when changes in the network topology occurred, during which time a loop could bring down the network, it was standardised as 802.1d by the Institute of Electrical and Electronics Engineers (IEEE). Perlman said that the benefits of the protocol amount to the fact that "you don't have to worry about topology" when changing the way a LAN is interconnected. Perlman has however criticised changes which were made in the course of the standardisation of the protocol.
From the paper "An Algorithm for Distributed Computation of a Spanning Tree in an Extended LAN":
Perlman was the principal designer of the DECnet IV and V protocols, which are part of the DECnet network protocol suite for peer-to-peer network architectures. She also made major contributions to the Connectionless Network Protocol (CLNP). Perlman has collaborated with Yakov Rekhter on developing network routing standards, such as the Open System Interconnection Routing Protocol (IDRP), which allows routers in packet switching networks to communicate with one another across broadcast domains. At DEC she also oversaw the transition from distance vector to link-state routing protocols. Link-state routing protocols had the advantage that they adapted to changes in the network topology faster, and DEC's link-state routing protocol was second only to the link-state routing protocol of the Advanced Research Projects Agency Network (ARPANET). While working on the DECnet project Perlman also helped to improve the intermediate-system to intermediate-system routing protocol, known as IS-IS, so that it could route the Internet Protocol (IP), AppleTalk and the Internetwork Packet Exchange (IPX) protocol.The Open Shortest Path First (OSPF) protocol relied in part on Perlman's research on fault-tolerant broadcasting of routing information.
Perlman subsequently worked as network engineer for Sun Microsystems, now Oracle. She specialised on network and security protocols and while working for Oracle obtained more than 50 patents.
Ethernet is a family of computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3, and has since retained a good deal of backward compatibility and been refined to support higher bit rates and longer link distances. Over time, Ethernet has largely replaced competing wired LAN technologies such as Token Ring, FDDI and ARCNET.
A network switch is a computer networking device that connects devices on a computer network by using packet switching to receive, process, and forward data to the destination device.
Network topology is the arrangement of the elements of a communication network. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial fieldbusses and computer networks.
DECnet is a suite of network protocols created by Digital Equipment Corporation. Originally released in 1975 in order to connect two PDP-11 minicomputers, it evolved into one of the first peer-to-peer network architectures, thus transforming DEC into a networking powerhouse in the 1980s. Initially built with three layers, it later (1982) evolved into a seven-layer OSI-compliant networking protocol.
The Spanning Tree Protocol (STP) is a network protocol that builds a loop-free logical topology for Ethernet networks. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them. Spanning tree also allows a network design to include backup links to provide fault tolerance if an active link fails.
The data layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between adjacent network nodes in a wide area network (WAN) or between nodes on the same local area network (LAN) segment. The data link layer provides the functional and procedural means to transfer data between network entities and might provide the means to detect and possibly correct errors that may occur in the physical layer.
Protocol-Independent Multicast (PIM) is a family of multicast routing protocols for Internet Protocol (IP) networks that provide one-to-many and many-to-many distribution of data over a LAN, WAN or the Internet. It is termed protocol-independent because PIM does not include its own topology discovery mechanism, but instead uses routing information supplied by other routing protocols. PIM is not dependent on a specific unicast routing protocol; it can make use of any unicast routing protocol in use on the network. PIM does not build its own routing tables. PIM uses the unicast routing table for reverse path forwarding.
Virtual Private LAN Service (VPLS) is a way to provide Ethernet-based multipoint to multipoint communication over IP or MPLS networks. It allows geographically dispersed sites to share an Ethernet broadcast domain by connecting sites through pseudowires. The term 'sites' includes multiplicities of both servers and clients. The technologies that can be used as pseudo-wire can be Ethernet over MPLS, L2TPv3 or even GRE. There are two IETF standards track RFCs describing VPLS establishment.
Local Area Transport (LAT) is a non-routable networking technology developed by Digital Equipment Corporation to provide connection between the DECserver 90, 100, 200, 300, 500, 700 and DECserver 900 terminal servers and Digital's VAX and Alpha and MIPS host computers via Ethernet, giving communication between those hosts and serial devices such as video terminals and printers. The protocol itself was designed in such a manner as to maximize packet efficiency over Ethernet by bundling multiple characters from multiple ports into a single packet for Ethernet transport. Over time, other host implementations of the LAT protocol appeared allowing communications to a wide range of Unix and other non-Digital operating systems using the LAT protocol.
The Multiple Spanning Tree Protocol (MSTP) and algorithm, provides both simple and full connectivity assigned to any given Virtual LAN (VLAN) throughout a Bridged Local Area Network. MSTP uses BPDUs to exchange information between spanning-tree compatible devices, to prevent loops in each MSTI and in the CIST, by selecting active and blocked paths. This is done as well as in STP without the need of manually enabling backup links and getting rid of bridge loops danger.
A computer network is a digital telecommunications network which allows nodes to share resources. In computer networks, computing devices exchange data with each other using connections between nodes. These data links are established over cable media such as wires or optic cables, or wireless media such as Wi-Fi.
George Varghese is a Principal Researcher at Microsoft Research. Before joining MSR's lab in Silicon Valley in 2013, he was a Professor of Computer Science at the University of California San Diego, where he led the Internet Algorithms Lab and also worked with the Center for Network Systems and the Center for Internet Epidemiology. He is the author of the textbook Network Algorithmics published by Morgan Kaufmann in 2004.
Data center bridging (DCB) is a set of enhancements to the Ethernet local area network communication protocol for use in data center environments, in particular for use with clustering and storage area networks.
TRILL is an IETF Standard implemented by devices called RBridges or TRILL Switches. TRILL combines techniques from bridging and routing and is the application of link state routing to the VLAN-aware customer-bridging problem. RBridges are compatible with and can incrementally replace previous IEEE 802.1 customer bridges. They are also compatible with IPv4 and IPv6 routers and end nodes. They are invisible to current IP routers and, like routers, RBridges terminate the bridge spanning tree protocol.
A routing bridge or RBridge, also known as a TRILL Switch, is a network device that implements the TRILL protocol, as specified by the IETF and should not be confused with BRouters. RBridges are compatible with previous IEEE 802.1 customer bridges as well as IPv4 and IPv6 routers and end nodes. They are invisible to current IP routers and, like routers, RBridges terminate the bridge spanning tree protocol.
Sally Floyd was an American computer scientist known for her work on computer networking. Formerly associated with the International Computer Science Institute in Berkeley, California, she retired in 2009 and died in August 2019. She is best known for her work on Internet congestion control, and was in 2007 one of the top-ten most cited researchers in computer science.
Bridge Protocol Data Units (BPDUs) are frames that contain information about the spanning tree protocol (STP). A switch sends BPDUs using a unique MAC address from its origin port and a multicast address as destination MAC . For STP algorithms to function, the switches need to share information about themselves and their connections. What they share are bridge protocol data units (BPDUs). BPDUs are sent out as multicast frames to which only other layer 2 switches or bridges are listening. If any loops are found in the network topology, the switches will co-operate to disable a port or ports to ensure that there are no loops; that is, from one device to any other device in the layer 2 network, only one path can be taken.
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