1、ANSI INCITS 295-1996 (R2001)(formerly ANSI X3.295-1996 (R2001)for Information Technology -Serial Storage Architecture -Transport Layer 1 (SSA-TL1)ANSI X3.295-1 996 American National Standard for Information Technology - Serial Storage Architecture - Transport Layer 1 (SSA-TLI) Secretariat Informatio
2、n Technology Industry Council Approved November 29, 1996 American National Standards Institute, Inc. Abstract This standard defines the transport layer of the Serial Storage Architecture (SSA). SSA defines a serial interface hierarchy to be used for purposes within its distance and perfor- mance cha
3、racteristics, including, but not limited to, storage subsystems. This standard is intended to be used with an upper layer protocol e.g., SCSI-2 Protocol (SSA-S2P), and a physical layer e.g., Physical Layer 1 (SSA-PHl). AmericanNationalStandardApproval of an American National Standard requires review
4、 by ANSI that 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.
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13、representation ismade or implied that this is the only license that may be required to avoid infringement in the use of this standard.Published byAmerican National Standards Institute11 West 42nd Street, New York, New York 10036Copyright 1997 by Information Technology Industry Council (ITI)All right
14、s reserved.No part of this publication may be 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 AmericaContents Page Foreword . . . . . . . . . . . . . . . . . . . . .
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16、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix 1 Scope 1 1.1 SSA-TLl characteristics . 1 1.2 SSA family of standards .2 2 Normative references . 3 3 Definitions, symbols, and abbreviations . .3 3.1 Definitions . 3 3.2 Symbols and abbreviations . 4 4 Conventions .5 5 Web . 6 5.1 Strings
17、 . 7 5.2 Loops 7 5.3 Complex web containing switches . . 8 6 88/i OB code 8 6.1 Data characters 9 6.2 Special characters . .lO 6.3 Initialization . 12 6.4 Code violations 13 6.5 Permitted special character sequences .l3 7 Frames . .13 7.1 CONTROL field . .15 7.2 STATUS field .16 7.3 PATH field .16 7
18、.4 ADDRESS field . .17 7.5 DATA field . 18 7.6 CRC field . 18 8 Protocol . 19 8.1 Router functions .19 8.2 Web routing .19 8.3 Node routing . .22 8.4 Flow control .22 8.5 SAT . 25 8.6 Priority for transmission 29 9 Link management . 30 9.1 Port attributes . .30 9.2 Node based data structures 36 9.3
19、Beginning communication process . .39 9.4 Configuration . 40 9.5 Resets .41 10 Error handling . .44 10.1 Link ERP 44 Page 10.2 Invalid SMS field handling . 50 10.3 Asynchronous alert process . .52 10.4 De-queue asynchronous alert process 52 10.5 ASYNC ALERT SMS handling process 53 10.6 MASTER ALERT
20、SMS handling process .55 11 SSA-TLl message structures .57 11 .l SMS validation .58 11.2 Privileged SMS 59 11.3 Application SMS .75 12 Transport layer processes . .78 12.1 Master negotiation process . 79 12.2 Master alive process . 80 Tables 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 2
21、3 24 25 ii Bit ordering in a byte . 5 5B/6B encoding rules . 9 3B/4B encoding rules . 10 Special characters 10 User Defined character definition 12 Frame contents 14 CONTROL field 15 FRAME TYPE field . 15 RESET TYPE field 15 Port table entry . 35 Queued asynchronous alert table entry . 35 Asynchrono
22、us alert address table entry .36 UNIQUE ID field . 37 Master asynchronous alert table entry .37 Configuration table entry . .38 Configutor table entry .39 Link status byte . .47 Receiver errors . .47 Recovery from corrupted ACK character pair .50 Response to non-zero reserved fields or reserved code
23、 values 5 2 Generic SSA-TLl message structure . .57 SSA-TLl messages supported . .57 ASYNC ALERT SMS . .59 Format of the ALERT CODE field . .59 ALERT CODE values 61 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 Page ASYNC REPLY SMS _ . 62 RETURN CODE field values .62 CONFIGURE
24、 PORT SMS . 63 MODE field values . .64 MASTER ALERT SMS * . 65 QUERY NODE SMS . 66 SSA-TLl VERSION field values 66 QUERY NODE REPLY SMS .67 Upper-level protocol code values . .66 QUERY PORT SMS 69 QUERY PORT REPLY SMS 69 SUPPORTED SPEED field . 70 CURRENT SPEED field 70 QUERY PROTOCOL SMS . .71 QUER
25、Y PROTOCOL REPLY SMS . .71 QUERY SWITCH SMS 72 QUERY SWITCH REPLY SMS 72 QUIESCE SMS 73 RESPONSE SMS . 74 RETURN CODE values . 74 DATA READY SMS . .75 DATA REPLY SMS . 76 DATA REQUEST SMS . .77 Figures 1 Relationship of the SSA standards . .2 2 Dual-port node . 6 3 A string 7 4 A dedicated connectio
26、n 7 5 A loop 7 6 A complex Web containing a cyclic path . .8 7 Generalized frame format . 14 8 Specific frame format . .15 9 ADDRESS field . .17 10 Path addressing . 22 11 Timing of acknowledgments . .24 . III Page 12 SAT operation for a loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
27、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 13 SAT operation for a string . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 14 Web with 2 SAT regions . . . . . . . . . . . . . . . . . . . .
28、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 15 State transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Annexes A Transport layer
29、data transfer processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 B Transport layer services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 C Examples of half and full d
30、uplex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Foreword (This foreword is not part of American National Standard X3.295-l 996.) This Serial Storage Architecture - Transport Layer 1 standard is designed to provide a transport layer
31、 acceptable to vendors, looking for an evolution from parallel SCSI, and systems designers looking for opportunities to more fully exploit the capabilities inherent to a serial bus. This standard was developed by Task Group X3TlO.l of Accredited Standards Committee X3 during 1993-96. The standards a
32、pproval process started in 1995. This standard contains three informative annexes that are not considered part of this standard. Requests for interpretation, suggestions for improvement and addenda, or defect reports are welcome. They should be sent to the X3 Secretariat, Information Technology Indu
33、stry Council, 1250 Eye Street, NW, Suite 200, Washington, DC 200053922. This standard was processed and approved for submittal to ANSI by Accredited Standards Committee on Information Technology, X3. Committee approval of the standard does not necessarily imply that all committee members voted for i
34、ts approval. At the time it approved this standard, the X3 Committee had the following members: James D. Converse, Chair Donald C. Loughry, Vice-Chair Kate McMillan, Secretary Organization Represented Name of Representative AMP, Inc . Ben Bennett Edward Kelly (Ah.) Apple Computer, Inc David K. Micha
35、el Jerry Kellenbenz (Alt.) AT SSA-TLl provides a flexible addressing scheme to allow the configuration of a Web into dedicated connections, strings, loops, and complex configurations including a switch; The Web supports peer-to-peer communication with frame multiplexing between any pair of ports; Th
36、e Web is self-configuring without the use of address switches; The link supports point-to-point physical connections only. Strings and loops are created by using dual port nodes with cut-through routing; The transport layer flow control allows operation from 5 MB/s at a distance of 2,5 km to 13 600
37、MB/s at a distance of 1 m. The actual data rates and distances depend on the cable assembly and the drivers and receivers used; The link makes optimum use of the physical medium by using full-duplex communication to avoid arbitration overhead and turn-around delay; Full duplex communication achieves
38、 an aggregate 40 MB/set bandwidth (20 MB/set in each direction) between two ports; The frames are constructedwith a minimum framing overhead (e.g., only 8 characters of overhead for a 128 byte data field); An architected error recovery procedure provides transparent frame recovery after a transmissi
39、on error; A Wrap mode is provided to allow fault isolation at a node; An optional line fault detector detects failures in the link; Cyclical paths allow a Web to be configured providing redundant access to a node; The transport layer is capable of simultaneously supporting multiple upper-level proto
40、cols (e.g., SCSI-2, SCSI-3, IPI-3, TCP/IP, etc.); o) The 128-byte frame size minimizes the gate count needed for buffers. 1 ANSI X3.295-l 996 This standard defines the following functions: a) the protocol (e.g., framing, addressing and flow control); b) link management (e.g., buffering, port states,
41、 resets, configuration and error recovery). 1.2 SSA family of standards The relationships of the SSA family of standards is illustrated in figure 1. Serial Storage Architectur Figure 1 - Relationship of the SSA standards 1.2.1 SSA-S2P Serial Storage Architecture - (SSA-S2P) SCSI-2 Protocol defines t
42、he SCSI-2 Protocol used with SSA-TLl or SSA-TL2. 1.2.2 SSA-S3P Serial Storage Architecture - (SSAS3P) SCSI-3 Protocol defines the SCSI-3 Protocol used with SSA-TL2. 1.2.3 SSA-TLl Serial Storage Architecture - (SSA-TLl) Transport Layer 1 defines the Transport layer that supports SSA-S2P and requires
43、SSA-PHI. 1.2.4 SSA-TL2 Serial Storage Architecture - (SSA-TL2) Transport Layer 2 defines the Transport layer that supports SSA-S2P and SSA-S3P and requires SSA-PHl or SSA-PH2. 1.2.5 SSA-PHl Serial Storage Architecture - (SSA-PHl) Physical Layer 1 defines the Physical layer that supports SSA-TLl and
44、SSA-TL2, and consists of the electrical characteristics of the interface and the connectors. 1.2.6 SSA-PH2 Serial Storage Architecture - (SSA-PH2) Physical Layer 2 defines the Physical layer that supports SSA-TL2, and consists of the electrical characteristics of the interface and the connectors. AN
45、SI X3.295-l 996 2 Normative references The following standard contains provisions which, through reference in this text, constitute provisions of this American National Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agre
46、ements based on this American National Standard are encouraged to investigate the possibility of applying the most recent editions of the standard listed below. Members of IEC and IS0 maintain registers of currently valid International Standards, and ANSI maintains registers for American National St
47、andards. ANSI X3.293-l 996, Information technology - Serial Storage Architecture - Physical Layer 1 (SSA- PHl) ANSI X3.294-l 996, Information technology - Serial Storage Architecture - SCSI-2 Protocol (SSA-S2P) 3 Definitions, symbols, and abbreviations 3.1 Definitions 3.1 .l 3.1.2 3.1.3 3.1.4 3.1.5
48、3.1.6 3.1.7 3.1.8 3.1.9 3.1.10 3.1.11 3.1.12 3.1.13 3.1.14 3.1.15 3.1.16 3.1.17 3.1.18 3.1.19 application: A process that is communicating via the link. APPLICATION: A possible value of the FRAME TYPE field. Application frame: A frame with a FRAME TYPE field value of APPLICATION. channel: The facili
49、ties in a port to receive an SMS or a single data transfer. character: A sequence of 10 encoded bits that represents a data byte or a protocol function. Configutor node: A node that knows the topology of the Web by performing the Configuration process. If a node is not a Configutor node, then it is a Responder node. CONTROL: A possible value of the FRAME TYPE field. CONTROL field: The first byte of a frame. Control frame: A frame with a FRAME TYPE field value of CONTROL. cut-through frames: Frames that ar
