1、I ANSIINCITS 231-1994 (R2004) (formerly ANSI X3.231-1994 (RI 999) for Information Systems - Fiber Distributed Data Interface (FDDI) - Physical Layer Protocol (PHY-2) Developed by Where IT all begins ANSI X3.231-1994 Am er can Nat io na I Standard for Information Systems - Fiber Distributed Data Inte
2、rface (FDDI) - Physical Layer Protocol (PHY-2) Secretariat Computer and Business Equipment Manufacturers Association Approved March 24, 1994 American National Standards Institute, Inc. Abstract The described Physical Layer Protocol Standard is intended for use in a high-performance multi- node netwo
3、rk. This protocol is designed to be effective at 100 megabits per second using a token ring architecture and fibre optics or other transmission media over distances of several kilometers in extent. Approval of an American National Standard requires review by ANSI that the requirements for due proces
4、s, consensus, and other criteria for approval have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more th
5、an a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, w
6、hether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any America
7、n National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the ti
8、tle page of this standard. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National St
9、andards may receive current information on all standards by calling or writing the American National Standards Institute. American National CAUTION: The developers of this standard have requested that holders of patents that may be required for the implementation of the standard disclose such patent
10、s to the publisher. However, neither the developers nor the publisher have undertaken a patent search in order to identify which, if any, patents may apply to this standard. As of the date of publication of this standard and following calls for the identification of patents that may be required for
11、the implementation of the standard, no such claims have been made. No further patent search is conducted by the developer or publisher in respect to any standard it processes. No representation is made or implied that licenses are not required to avoid infringement in the use of this standard. Publi
12、shed by American National Standards Institute 11 West 42nd Street, New York, New York 10036 Copyright O1 994 by Information Technology Industry Council (ITI) All rights reserved. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior
13、written permission of ITI, 1250 Eye Street NW, Washington, DC 20005. Printed in the United States of America Contents Foreword . Page . v 1 Scope . 1 . 2 Normative references . 3 Definitions . . 4 Conventions and abbreviations . 7 . 7 . 5 General description . 6 Services 6.1 PHY-to-DLL services . 6.
14、1.1 PH-UNITDATA.request 6.1 .I .2 When generated 6.1.2.2 When generated . . 13 6.2.1 .I Semantics of the primitive . 13 6.2.1.3 Effect of receipt . . 13 6.2.2.1 Semantics of the primitive . 14 6.2.2.3 Effect of receipt 6.2.3.1 Semantics of the primitive 6.2.3.2 When generated 6.2.3.3 Effect of recei
15、pt . 6.3 PHY-to-SMT services . . 14 6.3.1 SM-PH-LINE-STATE.request . 6.3.1 .I Semantics of the primitive . 15 6.3.1.2 When generated . 6.3.1.3 Effect of receipt . . 15 6.2.2 PM-UNITDATA.indication 6.2.2.2 When generated . . 14 6.2.3 PM-SIGNAL.indication 6.3.2 SM-PH-STATUS.indication 6.3.2.1 Semantic
16、s of the primitive 6.3.2.2 When generated 6.3.2.3 Effect of receipt . II Page 6.3.3.1 Semantics of the primitive 6.3.3.3 Effect of receipt 7 Facilities 7.1 .I Code bit . . 18 7.2 7.3 Symbol set . .20 7.2.1 Line state symbols .20 7.2.1.1 Quiet (Q) . 7.2.1.3 Idle(I) .20 7.2.2 Control symbols . 21 7.2.
17、2.1 Starting Delimiter (SD) . 7.2.2.1.2 Final SD symbol (K). 7.2.2.2 Other delimiter symbols . 7.2.2.2.1 Embe 7.2.2.2.2 Endin 7.2.2.3.1 Rese 7.2.2.3.2 Set s 7.2.3 Data Quartets (O-F) 7.2.4 Violation symbol (V) Line states . .23 7.3.1 Quiet Line State (QLS) 7.3.2 Halt Line State (HLS) 7.3.3 Master Li
18、ne State (MLS) 7.3.4 Idle Line State (ILS) 7.3.5 Active Line State (ALS). 7.3.6 Cycle Line State (CLS) . 7.3.7 7.2.2.3 Control Indicators . Noise Line State (NLS) 25 8.1 .I Coding . .26 8.1.2 Clocking . 8.1.3 Latency .28 8.2 Encode function 8.3 Transmit function . 30 8.4 Receive function. .30 8.5 De
19、code function . 8.6 Elasticity Buffer function . 31 .34 . III Page 8.8.2 Target Smoother 41 8.8.2.1 State TSO: Preamble (PA) . 41 8.8.2.2 State TSI: Service-Data- 44 .44 8.9.1 State RFO: IDLE . 45 8.9.2 State RF1 : REPEAT 45 8.9.3 State RF2: FILTER . 46 Table 1 Symbol coding 19 Fig u res 1 Structure
20、 of FDDI standards . 3 2 10 3 .27 4 Limit Smoother state diagram 38 5 Target Smoother state diagram .42 6 Repeat Filter state diagram . .47 7 FDDI-II jitter characteristics . 49 A Ring latency calculation . .50 8.9 Repeat Filter function . Peer Physical Connection example PHY functional block diagra
21、m example Annex iv Foreword (This foreword is not part of American National Standard X3.231-1994.) The Fibre Distributed Data Interface (FDDI) is intended for use in a high- performance general-purpose multi-node network and is designed for effi- cient operation with a peak data rate of 100 Mbit/s.
22、It uses a Token Ring architecture with optical fibre as the transmission medium. FDDI provides for hundreds of nodes operating over an extent of tens of kilometers. The Physical Layer Protocol (PHY) specifies the upper sublayer of the Physical Layer for the FDDI. As such, it presents the specificati
23、ons and services provided for conforming FDDI attachment devices. PHY specifies the data encode/decode, framing, and clocking requirements. PHY also specifies the elasticity buffer, smoothing, and repeat filter functions. When the set of basic FDDI standards is completed it will also include the fol
24、lowing standards: a) A Media Access Control (MAC), which specifies the lower sublayer of the Data Link Layer for FDDI, including the access to the medium, addressing, data checking, and data framing; b) A Physical Layer Media Dependent (PMD), which specifies the lower sublayer of the Physical Layer
25、for FDDI, including the power levels and characteristics of the optical transmitter and receiver, interface optical signal requirements including jitter, the connector receptacle footprint, the requirements of conforming FDDI optical fibre cable plants, and the permissible bit error rates; c) A Stat
26、ion Management (SMT), which specifies the local portion of the system management application process for FDDI, including the control required for proper operation of a node in an FDDI ring. SMT provides services such as connection management, station insertion and removal, station initialization, co
27、nfiguration management, fault isolation and recov- ery, communications protocol for external authority, scheduling policies, and collection of statistics. As of this writing, American National Standards for PHY (ANSI X3.148- 1988), MAC (ANSI X3.139-1987(R1992), and PMD (ANSI X3.166-1990) have been a
28、pproved and published, whereas the standard for SMT (ANSI X3.229-1994) is in production. In addition, FDDI standards are being pro- cessed as International Standards as parts of ISO/IEC 9314 by standards committee ISO/IEC JTCl/SC 25. International Standards for PHY, MAC, and PMD (IS0 9314-1:1989, 93
29、14-2:1989, and ISO/IEC 9314-3:1990, respectively) have been published as parts of ISO/IEC 9314 while a stan- dard for SMT is now in the approval process. Two extensions to the basic FDDI have been approved as American National Standards, The first (ANSI X3.186-1992), for Hybrid Ring Control (HRC), c
30、ommonly known as FDDI-II, extends the capability of FDDI to handle isochronous data streams at a multiplicity of data rates. The sec- ond (ANSI X3.184-1993), for a single mode optical fibre version of PMD (SMF-PMD), permits optical links of up to 60 km. Parts of ISO/IEC 9314 for both are in the appr
31、oval process. Other work currently in process, addressing alternate PMDs, is aimed at providing low-cost attachments for use in concentrator-to-workstation envi- ronments and for direct attachment to SONET links. V This American National Standard for PHY-2 is an enhancement to the original FDDI stan
32、dards on PHY (ANSI X3.148-1988 and IS0 9314-1). This standard will be referred to as PHY-2 when it is necessary to distinguish it from ANSI X3.148-1988. Changes from ANSI X3.148-1988 include those identified in footnotes to ANSI X3.148-1988 as areas that the standards committee intend- ed to change
33、as well as changes that were required for extensions to FDDI, such as FDDI-II. PHY-2 also includes editorial corrections and clarifications. A similar enhancement project, called MAC-2, has been designated as ANSI X3.239-1994, and is currently in production. Work leading toward MAC-2 and PHY-2 was i
34、nitiated by Task Group X3T9.5 in late 1988. Project proposals for these were submitted in 1988 and 1989, respectively. MAC was approved in November 1988 as Project 684-D and PHY was approved in March 1990 as Project 761-D. These original projects were worded as replacements of the existing standards
35、 but the project numbers were inadvertently assigned as new coexisting standards. In 1990 the project proposals were revised to specify new coex- isting standards (leaving the current MAC and PHY as active standards). The revised project proposals were approved in March 1991 with the same project nu
36、mbers retained. This work on PHY-2 progressed and an X3T9 technical letter ballot on it closed in December 1990. A number of comments were submitted. These were subsequently resolved and forwarded to Accredited Standards Committee (ASC) X3 for further processing as an American National Standard and
37、was approved by the June 1991 X3T9 Standards Committee meeting. Editing of the document to incorporate the required changes was completed in mid-1992. The subsequent X3 public review of PHY-2 result- ed in no comments. Following X3 public review, editorial comments sub- mitted by the IS0 editor were
38、 incorporated. The text and format of this document is based on International Standard IS0 9314-1. Furthermore, this standard is identical to the corresponding Draft International Standard for PHY-2 (DIS 9314-7). As a consequence, certain conventions, references, spelling, and units commonly used in
39、 International Standards have been used in this FDDI standard. These may be different than those normally used in American National Standards, but careful attention to the definitions conventions should avoid difficulty in understanding or use. This standard contains one annex. Annex A is informativ
40、e and is not part of this standard. Requests for interpretation, suggestions for improvement or addenda, or defect reports are welcome. They should be sent to the Computer and Business Equipment Manufacturers Association, 1250 Eye St., NW, Suite 200, Washington, DC 20005. This standard was processed
41、 and approved for submittal to ANSI by Accredited Standards Committee on Information Processing Systems, X3. Committee approval of this standard does not necessarily imply that all committee members voted for its approval. At the time it approved this standard, the X3 committee had the following mem
42、bers: James D. Converse, Chair Donald C. Loughry, Vice-Chair Joanne Flanagan, Secretary vi Organization Represented Name of Representative American Nuclear Society Geraldine C. Main Sally HartzeII (Alt.) AMP, Inc. Edward Kelly Charles Brill (Alt.) Apple Computer, Inc. . Karen Higginbottom Associatio
43、n of the Institute for Certification of Computer Professionals (AICCP) . Kenneth Zemrowski AT however, the FDDI protocols can support much larger networks by increasing these parameter values. As shown in figure 1, FDDI consists of: a) A Physical Layer (PL), which is divided into two sublayers: 1) A
44、 Physical Medium Dependent (PMD), which provides the digital baseband point-to-point communication between nodes in the FDDI network. The PMD provides all services necessary to transport a suitably coded digital bit stream from node to node. The PMD defines and characterizes the fibre-optic drivers
45、and receivers, medium-dependent code requirements, cables, connectors, power budgets, optical bypass provisions, and physical-hardware-related char- acteristics. It specifies the point of interconnectability for conforming FDDI attachments. The initial PMD standard defines attachment to multi-mode f
46、ibre. Alternative PMD sublayer standards are being developed for attachment to other transmission media and for mapping to Synchronous Optical Network (SON ET), 1 ANSI X3.231-1994 2) A Physical Layer Protocol (PHY), which provides connection between the PMD and the Data Link Layer. PHY establishes c
47、lock synchronization with the upstream code- bit data stream and decodes this incoming code-bit stream into an equivalent symbol stream for use by the higher layers. PHY provides encoding and decoding between data and control indicator symbols and code bits, medium conditioning and initializing, the
48、 synchronization of incoming and outgoing code-bit clocks, and the delineation of octet boundaries as required for the transmission of information to or from higher layers. Information to be transmitted on the medium is encoded by the PHY using a group transmission code. The definition of PHY is con
49、tained in this standard. b) A Data Link Layer (DLL), which is divided into two or more sublayers: An optional Hybrid Ring Control (HRC), which provides multiplexing of packet and circuit switched data on the shared FDDI medium. HRC comprises two internal components, a Hybrid Multiplexer (H-MUX) and an Isochronous MAC (I-MAC). H- MUX maintains a synchronous 125 ps cycle structure and multiplexes the packet and circuit switched data streams, and I-MAC provides access to circuit switched channels, A Media Access Control (MAC), which provides fair and deterministic access to the medium, addr
