Netwo;king Products Digital TechnicalJournal Digital Equipment Corporation Number 3 September I 986 Contents 8 Foreword William R. Johnson, Jr. New Products 10 Digital Network Architecture Overview Anthony G. Lauck, David R. Oran, and Radia J. Perlman 2 5 PerformanceAn alysis andModeling of Digital's Networking Architecture Raj Jain and William R. Hawe 35 The DECnetjSNA Gateway Product-A Case Study in Cross Vendor Networking John P:.. �orency, David Poner, Richard P. Pitkin, and David R. Oran ._ 54 The Extended Local Area Network Architecture and LANBridge 100 William R. Hawe, Mark F. Kempf, and Alan). Kirby 7 3 Terminal Servers on Ethernet Local Area Networks Bruce E. Mann, Colin Strutt, and Mark F. Kempf 88 The DECnet-VAXProduct -A n IntegratedAp proach to Networking Paul R. Beck and James A. Krycka 100 The DECnet-ULTRIXSoftware John Forecast, James L. Jackson, and Jeffrey A. Schriesheim 108 The DECnet-DOS System Peter 0. Mierswa, David). Mitton, and Ma�ha L. Spence 117 The Evolution of Network Management Products Nancy R. La Pelle, Mark). Seger, and Mark W. Sylor 129 The NMCCjDECnet Monitor Design Mark W. Sylor 1 Editor's Introduction The paper by Bill Hawe, Mark Kempf, and AI Kirby reports how studies of potential new broad­ band products led to the development of the Extended LAN Architecture. The design of the LANBridge 100, the first product incorporating that architecture, is described, along with the trade-offs made to achieve high performance. The speed of communication between terminals and systems depends on how they are connected. Bruce Mann, Colin Strutt, and Mark Kempf explain how they developed the LAT protocol to connect terminals to hosts on an Ethernet. The Ethernet Richard W. Beane Terminal Server, the DECserver 100, and the Editor DECserver 200 all use this new protocol. The next three papers describe how DNA was This third issue features papers about Digital's net­ incorporated into three different operating sys­ working products. Digital was an early advocate of tems. The first paper, by Paul Beck and Jim Krycka, distributed interactive computing, a concept explains how the DNA principles were built into allowing systems resources to be shared among the VAXJVMS system. The authors describe how many users over a network. Just as two persons transparency was achieved by a tight coupling frorri different cultures have problems communi· between the VMS software and the DECnet struc­ eating, however, so do computers with different ture. The ULTRIX software is Digital's second oper­ designs. Some standard set of rules is needed to ating system for its VAX computers. In the second allow successful interaction. paper, John Forecast, Jim Jackson, and Jeff The Digital Network Architecture (DNA) is the Schriesheim describe how they blended DNA into set of rules that defines how Digital's products the ULTRIX software. Several unique tools were communicate over a network. Being flexible, this developed to avoid changes to existing DNA imple­ architecture allows many ways for design ·groups to mentations. The DNA architecture has also been implement the DNA rules into various DECnet incorporated into the MS-DOS system in the products. DECnet-DOS product. The third paper, by Peter The first paper discusses the DNA structure and Mierswa, Dave Mitton, and Marty Spence, describes how it has evolved. Tony Lauck, Dave Oran, and how they built communication services into Radia Perlman describe DNA's design goals and the MS-DOS's background by writing new code and new functions supported in its four development borrowing existing code from the DECnet-ULTRIX phases. The tasks performed by the eight DNA lay­ software. ers are explained, with particular emphasis on the The final two papers discuss an important aspect network management and routing layers. of any network: its management. Nancy La Pelle, To achieve high performance, models and simu­ Mark Seger, and Mark Sylor discuss how network lations were used to test the DNA structure. The management is built into many diverse DECnet paper by Raj Jain and Bill Hawe relates some case products. They describe Digital's common man­ studies, one for each layer, that resulted in faster agement architecture and the need to meld the communication. These models helped to optimize management of voice and data networks. The how data packets.are handled by simulating differ­ NMCCJDECnet Monitor controls a DECnet network ent traffic patterns. from a central location. Mark Sylor relates how this Although the DNA and SNA architectures are monitor functions, describing its database struc­ quite different, they can communicate through the ture and reports for the network manager. The DECnetjSNA Gateway product. John Morency, monitor's analysis techniques to identify real-time Dave Porter, Richard Pitkin, and Dave Oran problems are especially interesting. describe how the gateway's design accomplishes I thank John Adams, Andrea Finger, and Walt this communication. The authors describe the Ronsicki for their help in preparing this issue. components in each architecture and how mes­ sages are structured. _2)� 0� 2 Biographies Paul R. Beck As a consulting software engineer, Paul Beck is currently the architect and was project leader for the DECnet-VAX product. He designed recovery mechanisms for high-availability software in the VMS group and was the network software architect for the DECdataway product. Before coming to Digital in 1977, he worked as a senior systems analyst at Applied Data Research, Inc. Paul earneda B.E.S. degree (1969) from Johns Hopkins University and an M.S.E.E. degree (1970) from Stanford University. He is a member of Tau Beta Pi and Eta Kappa Nu. John Forecast John Forecast received his B.A. degree from the University of Lancaster in 1971 and his Ph.D. degree from the University of Essex in 1975. Joining Digital in the United Kingdom in 1974, he later moved to the United States to join the newly formed group that developed the DECnet-RSX Phase 2 products. John held various positions within this group through the development of DECnet Phase IV, then worked on the DECnet­ ULTRIX project. He is currently a consulting software engineer irt the Local Area Systems Group. William R. Hawe A consulting engineer, Bill Hawe manages the Dis­ tributed Systems Architecture Group. He is designing new LAN interconnect system architectures and integrating ISO standards intj:> DNA. Bill helped to develop the Extended LANArchitect ure. For Corporate Research, he worked on the Ethernet design with Xerox and Intel Corporations and analyzed the performances of new communications technologies. Before joining Digital in 1980, Bill taught networking and electrical engin�ering at Southeastern Massachusetts University, where he earned his B.S.E.E.:and M.S.E.E. degrees. Bill is a member of the IEEE 802 Local Networks Standards Committee. James L. Jackson In 1976, Jim Jackson came to Digital after receiving a B.A.Sc . (E�E.) degree (1973) from the University of Waterloo and an M.Eng.Sc. (E.E.jC.S.) degree (1976) from the University of Queensland. He ' contributed to several projects since DECnet Phase 11 was conceived. Jim was project leaderjmanager for DECnet-ULTRIX V1.0 and was developer and project leader for multiple versions of DECnet-RSX and DECnet-IAS. He .also supervised a release of the DECnet Router and s01ire advanced develop· ment work. Currently, Jim is a software development manager working on distributed systems services projects. He is a member, of the IEEE. 3 Biographies RajJain Raj Jain graduated from A.P.S. University (B.E., 1972), the Indian Institute of Science (M.E., 1974), and Harvard University (Ph.D., 1978) . Joining Digital in 1978, he worked on performance modeling of VAXcluster systems, and Ethernet and other DNA protocols. During a one-year sabbatical at M.I.T., Raj taught a graduate course on modeling techniques. As a consult­ ing engineer, he is now engaged in performance modeling for distributed systems and networking architectures. A member of ACM and senior member of IEEE, Raj has written over 15 papers on performan�e analyses and is writ­ ing a textbook on performance analysis techniques. Mark F. Kempf Mark Kempf is currently involved in planning Digital's next generation of interconnect products. A consulting engineer, he was the project manager for advanced development of the LANBridge 1 00 and DECserver 100. Coming to Digital in 1979, Mark worked on software fo r a DECnet front end and one of Digital's first implementations of Ethernet. Ear­ lier, he worked at Standard Oil of Indiana on real-time process control sys­ tems. Mark earned a B.S. degree from Northwestern University in 1972. He holds three patents, including one in bridge technology. Alan J. Kirby As the manager of the Communications and Distributed Sys­ tems Advanced Development Group, Alan Kirby has managed and partici­ pated in the development of products such as the DECserver 1 00 and the LANBridge 1 00. Before joining Digital in 1981, Alan was the manager of net­ work development at National CSS, Inc., where he helped to design a large­ scale packet switching network. He received a B.S. degree (1974) in com­ puter science from Worcester Polytechnic Institute and an M.S. degree (1979) at the Polytechnic Institute of New York. Alan is a member of the IEEE. James A. Krycka A principal software engineer, Jim Krycka is a supervi­ sor in the VMS Development Group and project leader of the VMS Batch/ Print facility. Joining Digital in 1972. as a software specialist, he provided technical support for PDP-1 1 and PDP-8 systems. In the VMS group, Jim designed and implemented the remote file access portion of the DECnet­ VAX software . He also helped to design the data access protocol and repre­ sented Digital on the ANSI committee working on ISO networking standards.