Fiber Distributed Data Interface

Fiber Distributed Data Interface Digital Technical Journal Digital Equipment Corporation Volume 3 Number 2 Spring 1991 Editorial Jane C. Blake, Editor Kathleen M. Stetson, Associate Editor Circulation Catherine M. Phillips, Administrator Suzanne]. Babineau, Secretary Production Helen L. Patterson, Production Editor Nancy Jones, Typographer Peter Woodbury, Illustrator Advisory Board Samuel H. Fuller, Chairman Richard W Beane Robert M. Glorioso Richard]. Hollingsworth John W McCredie Alan G. Nemeth Mahendra R. Patel F. Grant Saviers Robert K. Spitz Victor A. Vyssotsky Gayn B. Winters The Digital Technicaljournal is published quarterly by Digital Equipment Corporation, 146 Main Street ML01-3/B68, Maynard, Massachusetts 01754-2571. Subscriptions to the Journal are $40.00 for four issues and must be prepaid in U. S. funds. University and college professors and Ph.D. students in the electrical engineering and computer science fields receive complimentary subscriptions upon request. Orders, inquiries, and address changes should be sent to The Digital Technicaljournal at the published-by address. Inquiries can also be sent electronically to Dl]®CRL.DEC.COM. Single copies and back issues are avai!able for $16.00 each from Digital Press of Digital Equipment Corporation, 12 Crosby Drive, Bedford, MA017 30-1493. Digital employees may send subscription orders on the ENE T to RDVAX::JOURNAL or by interoffice mail to mailstop ML01- 3/B68. Orders should include badge number, cost center, site location code and address. All employees must advise of changes of address. Comments on the content of any paper are welcomed and may be sent to the editor at the published-by or network address. Copyright© 1991 Digital Equipment Corporation. Copying without fee is permitted provided that such copies are made for use in educational institutions by faculty members and are not distributed for commercial advantage. Abstracting with credit of Digital Equipment Corporation's authorship is permitted. All rights reserved. The information in this Journal is subject to change without notice and should not be construed as a commitment by Digital Equipment Corporation. Digital Equipment Corporation assumes no responsibility for any errors that may appear in this Journal. ISSN 0898-901X Documentation NumberEY-H876E-DP The following are trademarks of Digital Equipment Corporation: CI, DDCMP, DEC, DECbridge, DECconcentrator, DEC FDDicontroller, DECnet, DECmcc, DECstation, DECWORLD, Digital, the Digital logo, DNA, I.AT, ThinWire, TURBOchannel, ULTRIX, VAX, VAXcluster, VMS. Cover Design AppleTalk is a registered trademark of Apple Computer, Inc. Our cover depicts the dual fiber-optic ring that isthe physical Cis a registered trademark of Microsoft Corporation. medium for high-speed transmission of data in Digital's new Motorola is a registered trademark of Motorola, Inc. FDD/local area network. High-performance workstations, SUN is a registered trademark and NFS is a trademark of Sun systems, servers, and other LANs can be easily connected to the Microsystems, Inc. ring through new bridge and wiring concentrator products, X Window System is a trademark of the Massachusetts Institute which are among the topics featured in this issue on FDDI. of Technology. UNIXis a registered trademark of UNIX System Laboratories, Inc. The cover was designed byDave Bryant of Digital's Media Book production was done by Digital's Media Communications Communications Group. Group in Bedford, MA. Contents 8 Foreword Mark F. Kempf Fiber Distributed Data Interface 10 Fiber Distributed Data Interface Overview William R. Hawe, Ri chard Graham, and Peter C. Hayden 19 Development of the FDDI Physical Layer jerry D. Hutchison, Christopher Baldwin, and Bruce W Thompso n 31 FDDI Data Link Development Henry S. Yang, Barry A. Spinney, and Stephen To wning 42 An Overview of the Common Node Software Paul W Ciarfclla, David Benson, and David S. Sawyer 53 Development of the DECbridge 500 Product Ro bert C. Kochem, James S. Hiscock, and BrianT. Mayo 64 The DECconcentrator 500 Product William]. Tiffany, G. Paul Ko ning, and james E. Kuenzel 76 DECelms-Managing Digital's FDDI and Ethernet Extended Local Area Networks Bruce E. Sweet 85 ULTRIX Fiber Distributed Data Interface Networking Subsystem Implementation Ursula Sinkewicz, Chran-Ham Chang, Lawrence G. Palmer, Craig Smelser, and Fred L. Templin I Editor'sIntroduction Consistent behavior in the physical and data link layers is managed by a set of reusable soft ware libraries called Common Node Software. Paul Ciarfella, Dave Benson, and Dave Sawyer relate the events that led to the development of CNS and describe its functions. CNS implements the proto cols defined by the FDDI station management stan dard and manages the fOf)[ chip set. CNS is included in the DECbridge and DECconcentrator products. The DECbridge '500 product is the bridge for traffic between the high-speed FDD! LAN and the slower Ethernet H02.::'> LANs. Design considerations Jane C. Blake and DECbridge functions are presented by Bob Editor Kochem, jim Hiscock, and Brian Mayo. Their discus Digital's fiber distributed data interface, FDDI, is a sion otJcrs insight into the complexities involved high-speed LAN that links workstations, systems, in connecting fANs with different data rates, frame and other local area networks such as Ethernet. formats, and frame sizes. This new !.AN offers distance as well as speed, and Bi ll Tiffany, Paul Koning , and jim Kuenzel then extends connections beyond the limits of a build describe the DECconcentrator '500 product. The ing to cover wider areas such as a campus. Papers DECconcentrator, the cornerstone of the FD])] LAN, in this issue of the Dip,ittt! Technical joumaf pro provides additional ports to which stations can be vide insights into the tech nology choices made connected by radially wired cables. The authors during FDDI development and describe the design examine the significance of Digital's choice of a dual of the layers and products that make up this 100- ring of trees topology, which led to the need for a megabit/second LA.J'\1 system. concentrator, and give detai Is of DECconcentrator Among the reasons Digital's engineers chose FDDI development. technology were its high speed, high throughput, Remote management of the DEC:concentrator and consistency with existing and evolving stan and DECbridge products, as well as of Ethernet dards. In this issue's opening paper, .Bill Hawe. Rich bridges, is provided by DECelms software. Bruce Graham , and Peter Hayden review these selection Sweet outlines the challenges DECelms developers criteria and discuss tbe reasoning behind the final faced, including an evolving ANSI FDDr standard choices. The authors additionally present an over and differences between FDDI and Ethernet tech vinv of FDDI layers and product operations, which nologies. He then describes the network nunage establishes a context for the papers that follow. ment architecture and gives details of features that The lowest FDDI layer provides the physical con benefit the network manager. nections for data transmission on the fiber-optic The final paper in this issue addresses the devel ring. In their paper, Jerry Hutchison , Chris Baldwin, opment of an adapter that allows high-performance and Bruce Thompson describe the operation of the RISC workstations to connect to FOOl. Ursula physical layer, the .functiona I partition in g. and the Sinkewicz, Chran-Ham Chang , Larry Palmer, Craig choice of chip set technologies. They then exam Smelser, and Fred Templin review ULTRIX support ine the distributed clocking scbeme ami present for the FDDr system and then give detai Is of the DEC the methods used in the design of the optical link FDDlcontroller 700 adapter, which provides a single (methods later adopted by the Physical Layer FDOJ attachment for DECstation '5000 workstations. 1Yiedium Dependent Working Group of the FDDI The authors have included discussions of relevant committee). performance data. Both the development of the physical layer and The editors thank Mark Kempf for his help in the next higher layer, the data link layer, resulted in initiating and preparing this issue, and for kind ly contributions to the ANSI f'DDI standard. Digital's agreeing to write the issue's Foreword. implementation of the data link layer is the subject of the next paper by Henry Yang, Barry Spinney. and Steve Towni ng. In acltl ition to presenting several key algorithms, the authors review the functions of the three data link chips. They conclude their paper with a discussion of chip simulation and test. 2 Biographies I Christopher Baldwin As a principal engineer in the Network Systems Engineering Group, Christopher Baldwin is responsible fo r the development of the fiber-optic physical layer standard fo r FDDI (I'M D) and helped develop the fiber-optic hardware used in FOOl products. He also worked on fiber-optic transmission fo r the LANBridge 200. Before joining Digital in 1986, Chris was a senior engineer at Polaroid Corporation. He holds a H.A. ( 1983, honors) in elec trical engineering from Brown University and an M.S. (1984)from the Institute of Optics at the University of Rochester. David Benson Software principal engineer Dave Benson is a member of the Communications Systems Engineering Group and the project leader for the Common Node Software. His next responsibility will be as a firmware project leader in the area of fu ture FOOl products. Previously, Dave designed and imple mented the physical layer portion of CNS, codeveloped the design verification test (OVT) monitor tool, and was a member of the hardware design team fo r the FODI tester. Dave came to Digital in 1986 with ten years' engineering experience from Honeywell Information Systems. Chran-Ham Chang Chran-Ham Chang is a member of the ULTRJX Network Engineering Group. As a senior software engineer, he is responsible fo r the ULTRJX FODIan cl Ethernet driver design and development. Earlier, Chran was involved in the analysis of ULTRJX network performance and in the design of performance tools.

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