1、ANSI INCITS 239-1994 (R1999)(formerly ANSI X3.239-1994 (R1999)for Information Systems Fibre Distributed DataInterface (FDDI) Token Ring Media AccessControl-2 (MAC-2)ANSI x3.239-i 994 American National Standard for Information Systems - Fibre Distributed Data Interface (FDDI) - Token Ring Media Acces
2、s Control-2 (MAC-2) Secretariat Computer and Business Equipment Manufacturers Association Approved May 23, 1994 American National Standards Institute, Inc. Abstract This Media Access Control Standard is intended for use in a high-performance multi-node network. This protocol is designed to be effect
3、ive at 100 megabits per second using a token ring architecture and fibre optics or other transmission media over distances of several kilometers in extent. AmericanNationalStandardApproval of an American National Standard requires review by ANSI that therequirements for due process, consensus, and o
4、ther 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 simplemajority, bu
5、t 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 approved the s
6、tandardsor 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.Moreover, no
7、 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.CAUTION NO
8、TICE: 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 currentinformation o
9、n all standards by calling or writing the American National StandardsInstitute.Published byAmerican National Standards Institute11 West 42nd Street, New York, New York 10036Copyright 1994 by Information Technology Industry Council (ITI)All rights reserved.No part of this publication may be reproduce
10、d 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 AmericaContents Page Foreword . iv 1 Scope . 1 2 Normative references .3 3 Definitions 4 4 Conventions and abbreviations . 6 4
11、.1 Conventions 6 4.1 .l Addressing 7 4.1 .2 Timing values and timers .7 4.2 Abbreviations a 5 General description . .10 6 Services . 11 6.1 MAC-to-LLC services . .12 6.1.1 MA-UNITDATA.request . .12 6.1 .2 MA-UNITDATA.indication .14 6.1 .3 MA-UNITDATA-STATUS.indication .15 6.1.4 MA-TOKEN.request . .1
12、6 6.2 MAC-to-PHY services 17 6.2.1 PH-UNITDATA.request . .17 6.2.2 PH-UNITDATA.indication . .18 6.2.3 PH-INVALID.indication . .18 6 3 MAC-to-H-MUX Services . .19 6.3 1 HM-MODE.indication . 19 6.3.2 HP-UNITDATA.request . 2 0 6 3.3 HP-UNITDATA.indication . 20 6.3.4 HP-INVALID.indication . . . . . . 21
13、 6.3.5 HP-MODE.request . . .21 6.4 MAC-to-SMT services . .22 6.4.1 SMMAINITIALlZEPt?OTOCOL.request . 2 2 6.4.2 SM-MA-CONTROL.request . .24 6.4.3 SM-MA-STATUS.indication . .26 6.4.4 SM-MA-UNITDATA.request . .26 6.4 5 SM-MA-UNITDATA.indication .29 6 4.6 SM-MA-UNITDATA-STATUS.indication .31 6.4.7 SM-MA
14、-TOKEN.request 31 7 Facilities . . . 3 2 7.1 Symbol set . . . . 3 2 7 1 .l Line state symbols . . .32 7.1 .2 Control symbols 33 7.1 .3 Data Quartets (O-F). .34 7.1 .4 Violation symbol (V). . .34 7.2 Protocol Data Units . .34 7 2.1 Token . . .35 7.2 2 Frame 35 7.3 Fields . .36 7.3 1 Preamble (PA) . .
15、 . . . . . 36 I Page 7.3.2 Starting Delimiter (SD) .36 7.3.3 Frame Control (FC) .36 7.3.4 Destination and source addresses .39 7.3.5 Routeing Information (RI) field .42 7.3.6 Information (INFO) field . .42 7.3.7 Frame Check Sequence (FCS) . .43 7.3.8 Ending Delimiter (ED). .44 7.3.9 Frame Status (FS
16、). . .45 7.4 Timers 46 7.4.1 Token-Holding Timer (THT) .46 7.4.2 Valid-Transmission Timer (TVX) . .46 7.4.3 Token-Rotation Timer (TRT). . 47 7.4.4 Late Counter (Late-ct) . .48 7.45 Token Counter (Token-ct). . .48 7.5 Frame counts . .48 7.5.1 Frame-ct . . . 48 7.5.2 Error-ct. . .48 7.5.3 Lost-ct . .4
17、8 7.5.4 Copied-ct .49 75.5 Transmit-ct .49 7.5.6 Not-Copied-ct . .49 8 Operation . .49 8.1 Overview . . .49 8.1 .1 Frame transmission. .49 8.1 .2 Token transmission . .50 8.1.3 Frame stripping 50 8.1 4 Ring scheduling . .50 8.1 .5 Ring monitoring . 53 8.2 Structure .55 8.3 Receiver . 56 8.3.1 Token
18、and frame validity criteria . .57 8.3.2 State RO: LISTEN .58 8.3.3 State Rl : AWAIT-SD (Await Starting Delimiter) . .59 8.3.4 State R2: RC-FR-CTRL (Receive Frame Control Field). . 5 9 8.3.5 State R3: RC-FR-BODY (Receive Frame Body). . .60 8.3.6 State R4: RC-FR-STATUS (Receive Frame Status). . .62 8.
19、3.7 State R5: CHECK-TK (Check Token) .64 8.4 Transmitter . .65 8.4.1 State TO: TX-IDLE (Transmitter Idle). .65 8.4.2 State Tl : REPEAT (Repeat) .67 8.4.3 State T2: TX-DATA (Transmit data) .69 8.4.4 State T3: ISSUE-TK (Issue Token). . .71 8.4.5 State T4: CLAIM-TK (Claim Token). .72 8.4 6 State T5. TX
20、-BEACON (Transmit Beacon) .73 Table 1 Interpretation of FC field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 ii Page Figures 1 FDDI structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21、 . . . . . . . . . . . . . . . . . . . . . . 3 2 Token ring logical configuration example . . . . . . . . . . . . . . . . . . . . . . . . _. 11 3 MAC Receiver state diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _. 75 4 MAC Transmitter state diagram . . .
22、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Annexes A Addressing .83 A.1 General structure . .83 A.2 Administration of addresses .83 A.2.1 Locally administered addresses .84 A.2.2 Universally administered addresses .84 A.3 Transmi
23、ssion order 85 A.3.1 Representation of addresses . .85 A.4 Group addresses 86 A.4.1 Broadcast address . 86 A.4.2 Assignment of group addresses for use in standards8 7 A.4.3 Group addresses assigned for use in FDDI . .87 A.5 Source routeing addressing . .87 A.6 References . .87 B Frame Check Sequence
24、 . . . .88 B.l Description .88 B.2 Generation of the FCS .88 B.3 Checking the FCS . .89 B.4 Implementation .89 B.5 Related standards . .91 C Bridging . .92 C.l Bridge architectures . . . . .92 C.2 Destination Address recognition . 92 C.3 Indicator setting . . . .93 C.4 Stripping . . . .93 D Elements
25、 of timer calculation . . . . .95 . . . III -_.-_- Foreword (This foreword is not part of American National Standard X3.239-i 994.) The Fibre Distributed Data Interface (FDDI) is intended for use in a high- performance general-purpose multi-station network and is designed for effi- cient operation w
26、ith a peak data rate of 100 Mbit/s. It uses a Token Ring architecture with optical fibre as the transmission medium. FDDI provides for hundreds of stations operating over an extent of tens of kilometers. The Media Access Control (MAC) specifies the lower sublayer of the Data Link Layer for the FDDI.
27、 As such, it presents the specifications and ser- vices provided for conforming FDDI attachment devices. MAC specifies the access to the medium, including addressing, data checking, and data framing. MAC also specifies the receiver and transmitter state machines. When the set of basic FDDI standards
28、 is completed, it will also include the following standards: a) A Physical Layer Protocol (PHY), which specifies the upper sublay- er of the Physical Layer for the FDDI, including the data encode/decode, framing and clocking, as well as the elasticity buffer, smoothing, and repeat filter functions;
29、b) A Physical Layer Media Dependent (PMD), which specifies the lower sublayer of the Physical Layer 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 requir
30、ements of conforming FDDI optical fibre cable plants, and the permissible bit error rates, c) A Station Management (SMT), which specifies 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. SMT pro
31、vides services such as connection management, station insertion and removal, station initialization, configuration manage- ment, fault isolation and recovery, communications protocol for exter- nal authority, scheduling policies, and collection of statistics. As of this writing, American National St
32、andards for PHY (ANSI X3.148- 1988), MAC (ANSI X3.139-1987(Rl992), and PMD (ANSI X3.166-1990) have been approved 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 by standards committee ISO/IE
33、C JTCl/SC 25. International Standards for PHY, MAC, and PMD (IS0 9314- 1 :1989, 9314-2:1989, and ISO/IEC 9314-3.1990, respectively) have been published, and a standard for SMT is now in the approval process. Two extensions to the basic FDDI have been approved as American National Standards and are i
34、n print. The first (ANSI X3.186-1992), for Hybrid Ring Control (HRC), commonly known as FDDI-II, extends the capa- bility of FDDI to handle isochronous data streams at a multiplicity of data rates. The second (ANSI X3.184-1992), for a single mode optical fibre ver- sion of PMD (SMF-PMD), permits opt
35、ical links of up to 60 km. Both are also being processed as International Standards by ISO/IEC JTCl/SC 25. Other work currently in process, addressing alternate PMDs, is aimed at pro- viding low-cost attachments for use in concentrator-to-workstation environ- ments. This work includes a Low-Cost Fib
36、er PMD (LCF-PMD) and a (copper) Twisted Pair PMD (TP-PMD), which are both in the approval process. iv This American National Standard for MAC-Z is an enhancement to the orig- inal FDDI standards on MAC (ANSI X3.139-1987 and IS0 9314-2). This standard will be referred to as MAC-2 when it is necessary
37、 to distinguish it from ANSI X3.139-1987. Changes from ANSI X3.139-1987 include those identified in footnotes to ANSI X3.139-1987 as areas that the standards committee intended to change as well as changes that were required for extensions to FDDI, such as FDDI-II and MAC bridging. A similar enhance
38、ment project, called PHY-2, has been designated as ANSI X3.231 -1994, and is currently in print. Work leading toward MAC-2 and PHY-2 was initiated by Task Group X3T9.5 in late 1988. Project proposals for these were submitted in 1988 and 1989, respectively. MAC-2 was approved in November 1988 as Proj
39、ect 684-D and PHY-2 was approved in March 1990 as Project 761-D. These original projects were worded as replacements of the existing standards but the project numbers were inadvertently assigned as new coexisting standards. In 1990, the project proposals were revised to specify new coexisting standa
40、rds (leaving the current MAC and PHY as active stan- dards). The revised project proposals were approved in March 1991 with the same project numbers retained. This work on MAC-2 progressed and an X3T9.5 technical letter ballot on Rev. 4.0 of MAC-2 closed December 1990. Many comments were submit- ted
41、, requiring a number of meetings to resolve all of them. Resolution was completed by August 1992 and an X3T9 technical letter ballot was issued in October 1992. This letter ballot resulted in only minor changes to MAC-2 and the December 1992 meeting of X3T9 approved forwarding MAC-2, Rev. 5.0, to Ac
42、credited Standards Committee (ASC) X3 for further pro- cessing as an American National Standard. The 4-month public review of MAC-2 was completed in July 1993 with no comments submitted. The text and format of this revision of MAC is based upon International Standard IS0 9314-2. As a consequence, ce
43、rtain conventions, references, spelling, and units commonly used in 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 defini- tions and conventions should avoid difficulty in unde
44、rstanding or use. This standard has four annexes, all of which are informative and are not part of the standard. Requests for interpretation, suggestions for improvement or addenda, or defect reports are welcome. They should be sent to the X3 Secretariat, Computer and Business Equipment Manufacturer
45、s Association, 1250 Eye Street, NW, Suite 200, Washington, DC 20005. This standard was processed 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 v
46、oted for its approval. At the time it approved this standard, the X3 Committee had the following members: James D. Converse, Chair Donald C. Loughry, Vice-Chair Joanne Flanagan, Secretary Organization Represented Name of Representative American Nuclear Society . . . . . . . . . . . . . . . . . . . .
47、 . . . . . . . . . . . . . . . . . . . . . . . . . . Geraldine C. Main Sally Hartzell (Alt.) V AMP, Inc . . . Edwar d Kelly Charles Brill (Alt.) Apple Computer, Inc. . . Karen Higginbottom AT however, the FDDI protocols can support much larger networks by increasing these parameter values. As shown
48、in figure 1, FDDI consists of a) A Physical Layer (PL), which is divided into two sublayers: 1) A Physical Medium Dependent (PMD), which provides the digital baseband point-to- point communication between nodes in the FDDI network. The PMD provides all ser- vices necessary to transport a suitably co
49、ded digital bit stream from node to node. The PMD defines and characterizes the fibre-optic drivers and receivers, medium- dependent code requirements, cables, connectors, power budgets, optical bypass provisions, and physical-hardware-related characteristics. It specifies the point of interconnectability for conforming FDDI attachments. The initial PMD standard, ISO/IEC 9314-3, defines attachment to multi-mode fibre. Additional PMD sublayer standards are being developed for attachment to single mode fibre and SONET. _. _ _-. ._ _-.- -:.-i-d.T;l;.-.- L-=m-.Lk
