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40-668: TRILL was designed as a successor to the Spanning Tree Protocol, both having been created by the same person, Radia Perlman . The catalyst for TRILL was an event at Beth Israel Deaconess Medical Center which began on 13 November 2002. The concept of Rbridges [sic] was first proposed to the Institute of Electrical and Electronics Engineers in 2004, who in 2005 rejected what came to be known as TRILL, and in 2006 through 2012 devised an incompatible variation known as Shortest Path Bridging . TRILL switches, or RBridges, run

80-496: A 'scientist' and was a little embarrassed that my project involved cute little kids". MIT media project later tracked her down and told her that she started a new field called tangible user interface from the leftovers of her abandoned project. 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

120-552: A B.S. and M.S. in Mathematics and a Ph.D. in Computer Science from MIT in 1988. Her doctoral thesis on routing in environments where malicious network failures are present serves as the basis for much of the work that now exists in this area. 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

160-399: A LOGO educational robot called a Turtle. Perlman has been described as a pioneer of teaching young children computer programming. Afterwards, she was inspired to make a new programming language that would teach much younger children similar to Logo, but using special "keyboards" and input devices. This project was abandoned because "being the only woman around, I wanted to be taken seriously as

200-444: 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". She graduated from Ocean Township High School in 1969. 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

240-513: A common broadcast domain — akin to the case of a network service access point address (NSAP) on an end system in CLNP. From the point of view of TRILL, a link can be any of a wide variety of link technologies, including IEEE 802.3 ( Ethernet ), PPP (Point to Point Protocol)., or a Pseudo-wire . Ethernet links between RBridges can incorporate IEEE customer or provider 802.1 bridges. In other words, an arbitrary bridged LAN appears to an RBridge as

280-511: A huge impact on how networks self-organize and move data. She also made large contributions to many other areas of network design and standardization: for example, enabling today's link-state routing protocols , to be more robust, scalable, and easy to manage. Perlman was elected a member of the National Academy of Engineering in 2019 for contributions to Internet routing and bridging protocols. She holds over 100 issued patents. She

320-510: A more mesh-like structure benefit to a greater extent from the multipathing and optimal paths provided by TRILL than networks with a more tree-like structure. A host with multiple interfaces running the Internet Protocol requires that each of the interfaces [or the group of interfaces in a team] have a unique address, whereas when using TRILL the multiple-interface host can have a single IP address for all of its interfaces attached to

360-513: A multi-access link. It is essential that only one RBridge act as the ingress RBridge for any given native frame and TRILL has an Appointed Forwarder mechanism to assure this. TRILL does allow load splitting of this duty on a link based on VLAN, so that only one RBridge on each link encapsulates and decapsulates native frames for each VLAN. RBridge ports can compatibly implement a wide variety of existing and proposed link level and IEEE 802.1 port level protocols including PAUSE (IEEE 802.3 Annex 31B),

400-401: A network engineer for Sun Microsystems , now Oracle . She specialized in network and security protocols and while working for Oracle and obtained more than 50 patents. When standarizing her work on TRILL , a combined bridging and routing protocol that proposes to supersede STP , she included version 2 of the earlier "Algorhyme": I hope that we shall one day see A graph more lovely than

440-413: A network to deliver data reliably by making it possible to design the network with redundant links. This setup provides automatic backup paths if an active link fails, and disables the links that are not part of the tree. This leaves a single, active path between any pair of network nodes. She is most famous for STP, which is fundamental to the operation of network bridges in many smaller networks. Perlman

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480-411: A position with Bolt, Beranek, and Newman (BBN), a government contractor that developed software for network equipment. While working for BBN, Perlman made an impression on a manager for Digital Equipment Corp and was offered a job, joining the firm in 1980. During her time working at Digital, she quickly produced a solution that did exactly what the team wanted it to; the Spanning Tree Protocol. It allows

520-402: A shared-media link, which avoids spawning additional copies of frames during a temporary loop. A reverse-path forwarding check and other checks are performed on multi-destination frames to further control potentially looping traffic. The first RBridge that a unicast frame encounters in a campus, RB1, encapsulates the received frame with a TRILL header that specifies the last RBridge, RB2, where

560-401: A tree. A graph to boost efficiency While still configuration-free. A network where RBridges can Route packets to their target LAN. The paths they find, to our elation, Are least cost paths to destination! With packet hop counts we now see, The network need not be loop-free! RBridges work transparently, Without a common spanning tree. IEEE 802.3 IEEE 802.3

600-532: Is a working group and a collection of standards defining the physical layer and data link layer 's media access control (MAC) of wired Ethernet . The standards are produced by the working group of Institute of Electrical and Electronics Engineers (IEEE). This is generally a local area network (LAN) technology with some wide area network (WAN) applications. Physical connections are made between nodes and/or infrastructure devices ( hubs , switches , routers ) by various types of copper or fiber cable . 802.3

640-560: Is an American computer programmer and network engineer. She is a major figure in assembling the networks and technology to enable what we now know as the internet. 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 , thus earning her nickname "Mother of the Internet". Her innovations have made

680-570: Is the author of a textbook on networking called “Interconnections: Bridges, Routers, Switches, and Internetworking Protocols” and coauthor of another on network security called “Network Security: Private Communication in a Public World”, which is a now popular college textbook. Her contributions to network security include trust models for Public Key Infrastructure, data expiration, and distributed algorithms resilient despite malicious participants. She left Digital in 1993 and joined Novell . Then, in 1997 she left Novell and joined Sun Microsystems . Over

720-460: Is the root of the distribution tree. The ingress RBridge selects which distribution tree the frame should travel along. Even though RBridges are transparent to Layer 3 devices, and all the links interconnected by RBridges appear to Layer 3 devices to be a single link, RBridges act as link routers in the sense that, in the forwarding of a frame by a transit RBridge, the outer Layer 2 header is replaced at each hop with an appropriate Layer 2 header for

760-442: Is unknown or to multicast or broadcast groups. In contrast to Spanning Tree Protocol, which ensures a loop-free network topology by blocking otherwise active ports, TRILL establishes paths over all active links. IS-IS was chosen because: To mitigate temporary loop issues, RBridges forward based on a header with a hop count . RBridges also specify the next-hop RBridge as the frame destination when forwarding unicast frames across

800-631: 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

840-537: The IEEE 802.1aq standard (Shortest Path Bridging – SPB) was considered the major competitor of TRILL. As one 2011 book noted, "the evaluation of relative merits and difference of the two standards proposals is currently a hotly debated topic in the networking industry." Neither standard has seen significant adoption, in contrast to more recent overlay approaches such as EVPN . Radia Perlman Radia Joy Perlman ( / ˈ r eɪ d i ə / ; born December 18, 1951)

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880-514: The IS-IS link-state routing protocol amongst themselves. In this protocol, connectivity is broadcast to all the RBridges, so that each RBridge knows about all the other RBridges, and the connectivity between them. This gives RBridges enough information to compute pair-wise optimal paths for unicast , and calculate distribution trees for delivery of frames either to destinations whose location

920-471: The LOGO Lab at the (then) MIT Artificial Intelligence Laboratory, programming system software such as debuggers . 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

960-573: The Link Layer Discovery Protocol (IEEE 802.1AB), link aggregation (IEEE 802.1AX), MAC security (IEEE 802.1AE), or port based access control (IEEE 802.1X). This is because RBridges are layered above the IEEE 802.1 EISS (Extended Internal Sublayer Service) with the exception that an RBridge port handles spanning tree and VLAN registration PDUs differently. Cisco FabricPath is a proprietary implementation of TRILL that utilizes

1000-466: The Association for Computing Machinery’s Special Interest Group on Data Communication (SIGCOMM). Perlman invented the spanning tree algorithm and protocol. While working as a consulting engineer at Digital Equipment Corporation (DEC) in 1984 she was tasked with developing a straightforward protocol that enabled network bridges to locate loops in a local area network (LAN). It was required that

1040-685: The OSI Inter-Domain Routing Protocol (IDRP), the OSI equivalent of BGP . 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

1080-530: The TRILL control plane (including IS-IS for Layer 2), but a non-interoperable data plane. Brocade Virtual Cluster Switching , uses the TRILL data plane but a proprietary control plane and so is not interoperable with standards conformant TRILL. The TRILL protocol provides mandatory support for the usual 4K VLANs and can optionally support 24-bit Fine Grain Labels (FGL) in addition to VLANs. During its development,

1120-481: The course of her career she has earned over 200 patents, 40 of them while working for Sun Microsystems, where in 2007 she held the title of Distinguished Engineer. She has taught courses at the University of Washington , Harvard University , MIT , and Texas A&M , 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

1160-418: The course of the standardization of the protocol. Perlman published a poem on STP, called 'Algorhyme': I think that I shall never see A graph more lovely than a tree. A tree whose crucial property Is loop-free connectivity. A tree which must be sure to span So packets can reach every LAN. First the root must be selected. By ID it is elected. Least cost paths from root are traced. In

1200-485: The frame is decapsulated. RB1 is known as the "ingress RBridge" and RB2 is known as the "egress RBridge". To save room in the TRILL header and simplify forwarding lookups, a dynamic nickname acquisition protocol is run among the RBridges to select two- octet nicknames for RBridges, unique within the campus, which are an abbreviation for the six-octet IS-IS system ID of the RBridge. The two-octet nicknames are used to specify

1240-421: The ingress and egress RBridges in the TRILL header. The TRILL header consists of six octets: the first two octets include a six-bit decrementing hop count, plus flags; the next two octets contain the egress RBridge nickname; the final two octets contain the ingress RBridge nickname. For multi-destination frames, the "egress RBridge nickname" specifies a distribution tree for the frame, where the (nick)named RBridge

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1280-516: The network. Perlman utilized 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

1320-465: The next hop, and the hop count is decreased. Despite these modifications of the outer Layer 2 header and the hop count in the TRILL Header, the original encapsulated frame is preserved, including the original frame's VLAN tag. Multipathing of multi-destination frames through alternative distribution tree roots and equal-cost multi-path routing (ECMP) of unicast frames are supported. Networks with

1360-407: 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". After graduation, she accepted

1400-405: The piano and French horn . While her mother helped her with her math homework, they mainly talked about literature and music. But she didn't feel like she fit underneath the stereotype of an "engineer" as she did not break apart computer parts. 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

1440-496: 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

1480-463: 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 standardized 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 connected. Perlman has however criticized changes which were made in

1520-594: The tree these paths are placed. A mesh is made by folks like me Then bridges find a spanning tree. Perlman was the principal designer of the DECnet IV and V protocols, and IS-IS , the OSI equivalent of OSPF . She also made major contributions to the Connectionless Network Protocol (CLNP). Perlman has collaborated with Yakov Rekhter on developing network routing standards, such as

1560-614: Was a Fellow at Dell Technologies . Perlman was born in 1951 , 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 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

1600-669: Was elected to the Internet Hall of Fame in 2014, and to 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 has invented the TRILL protocol to correct some of the shortcomings of spanning trees, allowing Ethernet to make optimal use of bandwidth. As of 2022, she

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