1、ANSI INCITS 186-1992 (R2002) (formerly ANSI X3.186-1992 (R1997)for Information Systems Fiber Distributed Data Interface (FDDI) Hybrid Ring Control (HRC)ANSIX3.186-1992American National Standardfor Information Systems Fiber Distributed Data Interface (FDDI) Hybrid Ring Control (HRC)SecretariatCompute
2、r and Business Equipment Manufacturers AssociationApproved May 8, 1992American National Standards Institute, Inc.AbstractThe described Hybrid Ring Control standard is intended for use in a high-performance multi-nodenetwork providing integrated packet and circuit switching capabilities. This protoco
3、l is designed tomultiplex FDDI MAC and Circuit Switched Symbols onto fibre optics or other transmission mediaover distances greater than several kilometers and at rates of 100 megabits per second andgreater.AmericanNationalStandardApproval of an American National Standard requires review by ANSI tha
4、t therequirements for due process, consensus, 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
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12、ational Standards Institute11 West 42nd Street, New York, New York 10036Copyright 1993 by Information Technology Industry Council (ITI)All rights reserved.No part of this publication may be reproduced in anyform, in an electronic retrieval system or otherwise,without prior written permission of ITI,
13、 1250 Eye Street NW,Washington, DC 20005.Printed in the United States of AmericaContentsPageiForewordii1 Scope .12 Normative references.13 Definitions.24 Conventions and abbreviations 65 General description .76 HRC services.157 Facilities328 Operation 42Figures1 Structure of FDDI standards.22 HRC cy
14、cle structure.83 Hybrid mode traffic types94 Bandwidth management hierarchy115 Data flow through an FDDI-II Monitor Station 126 Data flow through an FDDI-II Non-Monitor Station .137 Architectural block diagram of the H-mux 148 Architectural block diagram of the I-MAC 169 H-MUX Cycle structure at 100
15、 Mbps .3210 H-MUX Cycle Header.3311 Example of the interleaving of a Wideband Channel 3512 Example of the sorting of the Wideband Channels.3513 H-MUX Structure .5114 HRC Receive State diagram.5315 WBC Template Filter State diagram5416 HRC Cycle Control State diagram.7017 HRC Cycle Generate State dia
16、gram7118 WBC Template Generation State diagram.72AnnexesA Examples of the circuit-switch service class 84B FDDI station considerations .92C Isochronous call control procedures .97D Isochronous channel security .102E Isochronous bandwidth management104F Logical ranking of monitors.106Foreword (This f
17、oreword is not part of American National Standard X3.186-1992.)The Fiber Distributed Data Interface (FDDI) is intended for use in a high-performance general purpose multi-node network and is designed for efficient operation with a peak data rate of 100 Mbit/s. It uses a Token Ring architecture with
18、optical fiber as the transmission medium. FDDI provides for hundreds of nodes operating over an extent of tens of kilome-ters.Hybrid Ring Control (HRC) is an enhancement to the basic FDDI. Thisenhancement, commonly known as FDDI-II, extends the capability of FDDIto handle isochronous data streams at
19、 a multiplicity of data rates in addi-tion to the packet traffic carried by the basic FDDI.When the set of basic FDDI standards is completed it will include the fol-lowing standards:(a) A Media Access Control (MAC), which specifies the lower sublayer ofthe Data Link Layer for FDDI, including the acc
20、ess to the medium,addressing, data checking, and data framing.(b) A Physical Layer Protocol (PHY) which specifies the upper sublayer ofthe Physical Layer for the FDDI, including the specifications and servicesprovided for conforming FDDI attachment devices. PHY specifies the dataencode/decode, frami
21、ng, and clocking requirements. PHY also specifiesthe elasticity buffer, smoothing, and repeat filter functions.(c) A Physical Layer Media Dependent (PMD), which specifies the lowersublayer of the Physical Layer for FDDI, including the power levels andcharacteristics of the optical transmitter and re
22、ceiver, interface optical sig-nal requirements including jitter, the connector receptacle footprint, therequirements of conforming FDDI optical fiber cable plants, and the per-missible bit error rates. (d) A Station Management (SMT), which specifies the local portion of thesystem management applicat
23、ion process for FDDI, including the controlrequired for proper operation of a node in an FDDI ring. SMT provides ser-vices such as connection management, station insertion and removal, sta-tion initialization, configuration management, fault isolation and recovery,communications protocol for externa
24、l authority, scheduling policies, andcollection of statistics.As of this writing, American National standards for PHY (ANSI X3.148-1988), MAC (ANSI X3.139-1987), and PMD (ANSI X3.166-1990) havebeen approved and published, whereas the standard for SMT (ANSIX3.229-199x) is in still in process. In addi
25、tion, FDDI standards are beingprocessed as International Standards by standards committee ISO/IECJTC1/SC 25. International Standards for PHY, MAC, and PMD (ISO 9314-1:1989, 9314-2:1989 and ISO/IEC 9314-3:1990, respectively) have beenpublished while a standard for SMT (ISO/IEC 9314-6:199x) is now in
26、pro-cess,In addition to HRC, another extension to the basic FDDI is also in process.This extension (ANSI X3.184-199x), is for a single mode optical fiber ver-sion of PMD (SMF-PMD), will permit optical links of up to 60 km. This hasbeen approved as American National Standard and is now in the process
27、of being published. iiiiiOther work currently in process, addressing alternate PMDs, is aimed atproviding low-cost attachments for use in concentrator-to-workstation envi-ronments and for direct attachment to SONET links.The use of HRC requires the use of enhanced versions of MAC, PHY andSMT, design
28、ated MAC-2, PHY-2 and SMT-2, respectively. Each of thesethree enhanced standards is required to be interoperable with the corre-sponding basic standard when FDDI is operating in basic mode.The dpANS for PHY-2 and MAC-2 were balloted by X3T9.5 in December1990. Both received extensive comments on this
29、 ballot. These commentshave been resolved and PHY-2 (ANSI X3.231-199x) and MAC-2 (ANSIX3.239-199x) were approved for forwarding to X3 for approval by the June1991 and December 1992 X3T9 meetings, respectively. In addition to thechanges required to support HRC, these documents include miscellaneoused
30、itorial corrections and technical clarifications, and in the case of MAC-2,the changes to support MAC bridging.SMT-2 has been divided into three documents, SMT-2-CS (CommonServices), SMT-2-PS (Packet Services) and SMT-2-IS (IsochronousServices). The first two of these are based on SMT and provide th
31、e sameservices, whereas SMT-2-IS is a entirely new document to support theisochronous services provided by HRC.A standards project for HRC was first formally proposed at the June 1985X3T9.5 meeting and was subsequently approved as project 573D. Thetechnical work on HRC was done in a series of ad hoc
32、 working meetingsauthorized by X3T9.5 that are collectively referred to as the FDDI-II work-ing meetings. The early work of the FDDI-II working group was document-ed in an FDDI-II working paper that was subsequently converted to theHRC dpANS.HRC was first approved for forwarding to X3 for approval b
33、y the April 1989X3T9 meeting. The first public review of HRC was completed in January1990 with the only comments being those submitted by the FDDI-II workinggroup. The second X3 public review was completed with no commentsand the first X3 letter ballot closed in December 1990 with the only com-ment
34、(on a YES ballot) being one submitted on behalf of the FDDI-II work-ing group The June 1991 meeting of X3T9 approved this version of HRC,which is being published as a standard, for forwarding to X3 for approval.An International Standard for HRC (ISO/IEC 9314-5-199x) is also in pro-cess and has been
35、approved for publishing. There are minor editorial dif-ferences between it and this standard on HRC.This standard contains six informative annexes. These annexes are forinformation only, and are not considered to be a part of the standard.This standard was processed and approved for submittal to ANS
36、I byAccredited Standards Committee on Information Processing Systems, X3.Committee approval of this standard does not necessarily imply that allcommittee members voted for its approval. At the time it approved thisstandard, the X3 committee had the following members:ivRichard Gibson, ChairDonald C.
37、Loughry, Vice-ChairJoanne Flanagan, Administrative SecretaryOrganization Represented Name of RepresentativeAllen-Bradley Company Ronald H. ReimerJoe Lenner (Alt.)American Library Association.Paul PetersAmerican Nuclear SocietyGeraldine C. MainSally Hartzell (Alt.)AMP, Inc. Edward KellyEdward Mikoski
38、 (Alt.)Apple Computer, IncKaren HigginbottomAssociation of the Institute for Certification of Computer Professionals Kenneth ZemrowskiEugene M. Dwyer (Alt.)AT MAC or MAC-2 otherwise. PHY-2 with HRC; PHY or PHY-2 otherwise. PMD, SMF_PMD, TP-PMD or LCF-PMD.Figure 1 Structure of FDDI standards2)At the
39、time of publication, this standard was under development. Contact the seCretariat for more recentinformation.ANSI X3.186-19923.2 Channel: The term “channel” is a synonym for “transmission channel”.3.3 Circuit: A circuit is a bidirectional communications capability provided over a continuousisochrono
40、us channel(s) between two or more CS-MUX level entities.3.4 Circuit switching: Circuit switching is the service that provides and manages a set of circuits.3.5 Circuit Switching Multiplexer (CS-MUX): A CS-MUX multiplexes and demultiplexes cir-cuits onto Transmission Channels for transmission.3.6 Con
41、nection: A connection is a concatenation of circuits and other functional units set up toprovide for the transfer of signals between two or more points in a telecommunications network.3.7 Cycle: The cycle is the HRC frame. It has a duration of 125 microseconds and nominallycarries 3 120 symbols at 1
42、00 Mbps.3.8 Cycle Control field: The Cycle Control field is a two symbol field in the Cycle Header. Onesymbol is for synchronization control while the other is for sequence control. These are used toindicate whether or not cycle synchronization and sequence, respectively, are being maintained.Each o
43、f these fields may only be set by the Cycle Master.3.9 Cycle Header: The Cycle Header begins with the Preamble, which establishes the bound-ary of the 125 microsecond cycle. The remainder of the Cycle Header provides synchronizationcontrol, sequence control, a cycle sequence field and the cycle prog
44、ramming template.3.10 Cycle Master: One ranked monitor in an FDDI-II ring assumes the role of the CycleMaster. The ring has only one Cycle Master at a time. The Cycle Master is responsible for gener-ating and maintaining the Cycle Structure and the timing of the ring. The Cycle Master inserts aLaten
45、cy Adjustment Buffer to adjust the ring size to be an integer multiple of 125 microseconds.The Cycle Master is selected by bidding among ranked Monitor Stations - the monitor with thehighest rank becomes the Cycle Master.3.11 Cycle Sequence: Cycle Sequence is a scheme for indicating whether or not t
46、he correct orderof cycle transmission is being maintained during normal Hybrid Mode operation. The sequence num-ber of each cycle is indicated in the Cycle Sequence field of the Cycle Header. Cycle Sequence val-ues 1-63 are used to indicate Monitor ranking, and values 64-255 are used for sequencing.
47、3.12 Cycle Structure: The Cycle Structure defines the format of the cycle. The cycle is struc-tured into the preamble, Cycle Header, Dedicated Packet Group and Cyclic Groups.3.13 Cyclic Groups: The Cycle Structure contains 16 Wideband Channels (WBCs), which arebyte interleaved with each other. The i
48、nterleaving scheme physically organizes the WBCs into 96Cyclic Groups per cycle, at 100 Mbps. Each Cyclic Group contains one byte from each WBC. Thebytes from each WBC occur in the same position in each Cyclic Group.3.14 Dedicated Packet Group: The Dedicated Packet Group is the part of the Cycle Str
49、ucturewhich provides a minimum packet channel bandwidth of 0,768 Mbps (at 100 Mbps).3.15 Entity: An entity is an active functional agent within an (OSI) layer or sublayer, includingboth operational and management functions.3.16 Fiber Optics: The technology whereby optical signals from light-generating transmittersare propagated through optical fiber waveguides to light-detecting receivers.3.17 Hybrid Isochronous-MAC Service Access Point (HI-SAP): HI-SAPs are the isochronousaccess points of the H-MUX. They are used by the I-MAC to access the WBCs.3.18 Hybrid Mode: An FDDI-II networ
