1、 ANSI INCITS 148-1988 (R1999)(formerly ANSI X3.148-1988 (R1999)for Information Systems Fiber Distributed DataInterface (FDDI) Token Ring Physical LayerProtocol (PHY) AmericanNationalStandardApproval of an American National Standard requires review by ANSI that therequirements for due process, consen
2、sus, and other criteria for approval havebeen met by the standards developer.Consensus is established when, in the judgment of the ANSI Board of StandardsReview, substantial agreement has been reached by directly and materiallyaffected interests. Substantial agreement means much more than a simplema
3、jority, but not necessarily unanimity. Consensus requires that all views andobjections be considered, and that a concerted effort be made toward theirresolution.The use of American National Standards is completely voluntary; their existencedoes not in any respect preclude anyone, whether he has appr
4、oved the standardsor 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 inno circumstances give an interpretation of any American National Standard.Mo
5、reover, no person shall have the right or authority to issue an interpretation ofan American National Standard in the name of the American National StandardsInstitute. Requests for interpretations should be addressed to the secretariat orsponsor whose name appears on the title page of this standard.
6、CAUTION NOTICE: This American National Standard may be revised orwithdrawn at any time. The procedures of the American National StandardsInstitute require that action be taken periodically to reaffirm, revise, or withdrawthis standard. Purchasers of American National Standards may receive currentinf
7、ormation on all standards by calling or writing the American National StandardsInstitute.Published byAmerican National Standards Institute11 West 42nd Street, New York, New York 10036Copyright 1988 by Information Technology Industry Council (ITI)All rights reserved.No part of this publication may be
8、 reproduced in anyform, in an electronic retrieval system or otherwise,without prior written permission of ITI, 1250 Eye Street NW,Washington, DC 20005.Printed in the United States of AmericaANSI X3.148-1988 American National Standard for Information Systems - Fiber Distributed Data Interface (FDDI)
9、 - Token Ring Physical Layer Protocol (PHY) Secretariat Computer and Business Equipment Manufacturers Association Approved June 30, 1988 American National Standards Institute, Inc Abstract This American National Standard on the physical layer protocol is intended for use in a high-perfor- mance mult
10、istation network. This protocol is designed to be effective at 100 megabits per second (Mbit/s) using a Token Ring architecture and fiber optics as the transmission medium over distances of several kilometers in extent. Foreword (This Forpword is not part of American National Standard X3.148-lQ88.)
11、The Fiber Distributed Data Interface (FDDI) is intended for use in a high-performance general purpose multistation network and is designed for efficient operation with a peak data rate of 100 Mbit/s. It uses a Token Ring architecture with optical fiber as the transmission medium. FDDI provides for h
12、undreds of stations 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 specifications and services provided for conforming FDDI attachment devices. PHY specifies the data encode/d
13、ecode, framing, and clocking requirements. PHY also specifies the elasticity buffer, smoothing, and repeat filter functions. PHY is the second of a set of American National Standards for FDDI. When this set is completed it will also include the following: (1) A Media Access Control (MAC) standard, w
14、hich specifies the lower sublayer of the Data Link Layer for FDDI, including the access to the medium, addressing, data checking, and data framing (2) A Physical Layer Media Dependent (PMD) standard, which specifies the lower sublayer of the Physical Layer for FDDI, including the power levels and ch
15、aracteristics of the optical transmitter and receiver, interface optical signal requirements Including jitter, the connector receptacle footprint, the requirements of conforming FDDI optical fiber cable plants, and the permisslble bit error rates (3) A Station Management (SMT) standard, which specif
16、ies the local portion of the system management application process for FDDI, including the control required for proper operation of a station in an FDDI ring The idea of developing a new high-speed data interface for computers based on the use of optical fiber was first raised in subcommittee X3T9.5
17、 at the October 1982 meeting. An ad hoc task group was formed to examine the issues and three project proposals, for the FDDI Physical, Data Link, and Network layers were developed and subsequently approved by the X3 committee (Projects 379D, 380D and 382D). Initial proposals for the Media Access Co
18、ntrol (MAC), corresponding to the lower half of the Data Link Layer, and for the Physical (PHY), corresponding to the Physical Layer, were both submitted in June 1983. FDDI adopted the structures of the ANSI/IEEE 802 Series, and early work indicated that the FDDI MAC could be developed to operate un
19、der the Logical Link Control (LLC) described in the ANSI/IEEE 802 Series. This decision, in effect, obviated the development of LLC or Network Layer standards unique to FDDI. The February 1986 X3TQ meeting unanimously forwarded MAC (Rev. 10) to X3. subsequently been MAC has approved as an American N
20、ational Standard (American National Standard for Information Systems - Fiber Distributed data Interface (FDDI) - Token Ring Media Access Control (MAC) ANSI X3.139-1987). In June of 1984, recognizing that fiber technology was not yet then sufficiently settled and that critical FDDI development work w
21、as dependent upon the protocol portions of the PHY document, Subcommittee X3T9.5 decided to divide the Physical layer into two parts (PHY and PMD), with the PHY document retaining only the upper sublayer of the Physical Layer. This allowed the work on PHY to proceed in parallel with the work on the
22、optical fiber components and interface. An X3TQ letter ballot unanimously approved forwarding of PHY (Rev. 11) to the X3 Committee in August 1985. During the initial public review period comments on the PHY document were generated within the technical committee X3T9.5 Itself. PHY, as revised (Rev. 1
23、4), was unanimously approved by the August 1986 X3TQ meeting for return to X3 for its second public review. A problem with the specification of the elasticity buffer function surfaced in the X3 letter ballot, which closed in March 1987. This problem was subsequently resolved by adding a smoothing fu
24、nction to the PHY specification and PHY (Rev. 15) was unanimously returned to X3 by the August 1987 X3T9 meeting. This document was subsequently approved as an American National Standard. Meanwhile, issues concerning FDDI optical fiber hardware systems were being addressed. With the division of the
25、Physical Layer, the second document, Physical Layer Media Dependent (PMD), would specify these optical fiber hardware system(s). A project proposal for this development work was submitted to committee X3 In June 1985 and subsequently approved (Project 541D). Work proceeded on the PMD document with m
26、ajor activity in a number of highly technlcal areas addressing the optical fiber to FDDI statlon interface. The February 1987 X3TQ subcommittee meeting unanimously approved PMD (Rev. 7) for forwarding to X3. The public review of PMD resulted in comments noting areas where refinements were required a
27、nd once again raised the issue of the connector footprint choice. These issues were all resolved and the June 1988 X3T9.5 meeting unanimously voted to forward PMD (Rev. 8) to X3 for further processing. In early 1984, subcommittee X3T9.5 recognized the need for a separate Station Management (SMT) doc
28、ument. The August 1984 X3T9 meeting approved a project proposal for submission to committee X3 and this was subsequently approved (Project 503D). This development work remains under way in the X3T9.5 technical subcommittee. During the standards development process in Subcommittee X3T9.5, FDDI has re
29、ceived support from a wide range of participants, including manufacturers of both computer and communications equipment, semiconductor manufacturers, suppliers of optical fiber components, and government agencies. With the FDDI MAC now approved as American National Standard X3.139-1987, the FDDI PHY
30、 represents the second in the set of four standards that comprise the basic FDDI. The FDDI documents are also being processed as IS0 standards. Both the FDDI MAC and PHY documents, DIS 9314-2 and 9314-1 respectively, passed the IS0 JTCl letter ballots in January 1988 for approval as International St
31、andards. Revision 8 of the PMD document (DIS 9314-3) is due to be balloted in late 1988. Suggestions for improvement of this standard will be welcome. They should be sent to the Computer and Business Equipment Manufacturers Association, 311 First Street, NW, Washington, DC 20001. This standard was p
32、rocessed and approved for submittal to ANSI by the 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 f
33、ollowing members: Richard Gibson, Chair Donald C. Loughry, Vice-Chair Catherine A. Kachurik, Administrative Secretary Orgathation Represented American Ubrary Assooclatlon . Amerfqan Nuclear Society. . AMP Incorporated . Apple Association of the lnstltute for Certfficatlon of Computer Professlonais .
34、 AT Secondary Link ISO PH,UNITDATA.request - I I 4 Station #M 1 I Station #N - -I k - PO = Primary Out PI = Primary In SI = Secondary In so = Secondary Out Figure 1 FDDI Physical Connection Example entity. An active element within an Open System Interconnection (OSI) layer, or sublayer; or SMT, in a
35、 specific station. fiber optics. A technology whereby signals are transmitted over an optical waveguide medium through the use of light-generating transmitters and light-detecting receivers. frame. A Protocol Data Unit transmitted between cooperating MAC entities on a ring, consisting of a variable
36、number of octets. nonreturn to zero (NRZ). A technique in which a polarity level high, or low, represents a logical 1 (one), or 0 (zero). nonreturn to zero invert on ones (NRZI). A technique in which a polarity transition represents a logical 1 (one). The absence of a polarity transition denotes a l
37、ogical 0 (zero). physical connection. The full-duplex physical layer association between adjacent PHY entities (in concentrators, repeaters, or stations) in an FDDI ring, i.e., a pair of Physical Links. physical link. The simplex path (via PMD and attached medium) from the transmit function of one P
38、HY entity to the receive function of an adjacent PHY entity (in concentrators, repeaters, or stations) in an FDDI ring. primitive. An element of the services provided by one entity to another. Protocol Data Unlt (PDU). Information delivered as a unit between peer entities that may contain control in
39、formation, address information and data (e.g., an Service Data Unit from a higher layer). receive. The action of a station of accepting a frame, token, or control sequence from the medium. repeat. The act of a station in receiving a code-bit stream (e.g., frame or token) from an upstream station and
40、 placing it on the medium to the next station. The station repeating the code-bit stream examines it and may copy it into a buffer and modify control indicators as appropriate. ring. Two or more stations In which information is passed sequentially between active stations, each station in turn examin
41、ing or copying the information, finally returning it to the originating station. Service Data Unit (SDU). The unit of data transfer between a service user and a service provider. services. The services provided by one entity to a higher entity or to SMT. station. An addressable logical and physical
42、node on a ring capable of transmitting, repeating, and receiving information. II AMERICAN NATIONAL STANDARD X3.148-1988 Station Management (SMT). The entity within a station on the ring that monitors station activity and exercises overall appropriate control of station activity. symbol. The smallest
43、 signaling element used by the Data Link Layer (DLL). The symbol set consists of sixteen data symbols and eight control symbols. Each symbol corresponds to a specific sequence of code bits (code group) to be transmitted by the Physical Layer. transmlt. The action of a station that consists of genera
44、ting a frame, token, or control sequence, and placing it on the medium to the next station. 2.3 Conventions. The terms SMT, MAC, PMD, and PHY, when used without modifiers, refer specifically to the local entities. Underbars (e.g., control-action) are used as a convenience to mark the name of signals
45、, functions, and the like, which might otherwise be misinterpreted as independent individual words if they were to appear in text. The use of a period (e.g., Pi-l-UNITDATA.request) is equivalent to the use of underbars except that a period is used as an aid to distinguish modifier words appended to
46、an antecedent expression. 8. services This section specifies the services provided by PHY. The services as defined in this section do not imply any particular implementation or any interface. Services described are: (1) PHY services provided to the local MAC entity (indicated by Pli- prefix) (2) Ser
47、vices required from the local PMD entity by PHY (indicated by PM- prefix) (3) PHY services provided to the local SMT entity (indicated by SM-PH.- prefix) Figure 2 shows the block diagram organization of the FDDI Physical layer including the separate functions, related 12 signals and interfaces that
48、it contains. The interfaces and signals between the Physical Layer, the data link layer and Station Management are intended to be logical rather than physical. Any other set of signals that causes the same physical behavior of the protocol is equally valid. 3.1 PHY-to-MAC Services. This subsection s
49、pecifies the services supplied by PHY to allow the local MAC entity to exchange PDUs with peer entities. Additional detail is provided in MAC concerning conditions that generate these primitives and MAC actions upon receipt of PHY-generated primitives. The following primitives are defined: PtCUNITDATA.request PH-UNITDATA.indication Pi-i-UNITDATA-STATUS.indication PHJNVALID.lndication All primitives described in this section are mandatory. The description of each primitive includes a description of the information that shall be passed bet
