1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 1.361 (02/99) SERIES I: INTEGRATED SERVICES DIGITAL NETWORK O.veral1 network aspects and functions - Protocol layer requirements B-ISDN ATM layer specification ITU-T Recommendation 1.361 (Previously CClTT Rec
2、ommendation) ITU-T I-SERIES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK 2ENERAL STRUCTURE Terminology Description of ISDNs General modelling methods Telecommunication network and service attributes General description of asynchronous transfer mode Scope General aspects of services in ISDN Co
3、mmon aspects of services in the ISDN Bearer services supported by an ISDN Teleservices supported by an ISDN Supplementary services in ISDN SERVICE CAPABILITIES OVERALL NETWORK ASPECTS AND FUNCTIONS Network functional principles Reference models Numbering, addressing and routing Connection types Perf
4、ormance objectives 1.110-1.119 1.120-1.129 1.130-1.139 1.140-1.149 1.150-1.199 1.200-1.209 1.210-1.219 1.220-1.229 1.230-1.239 1.240-1.249 1.250-1.299 1.310-1.319 1.320-1.329 1.330-1.339 I. 3404.349 1.350-1.359 General network requirements and functions ISDN USER-NETWORK INTERFACES Application of I-
5、series Recommendations to ISDN user-network interfaces Layer 1 Recommendations Layer 2 Recommendations Layer 3 Recommendations Multiplexing, rate adaption and support of existing interfaces Aspects of ISDN affecting terminal requirements INTERNETWORK INTERFACES MAINTENANCE PRINCIPLES B-ISDN EQUIPMEN
6、T ASPECTS ATM equipment Transport functions Management of ATM equipment 1.370-1.399 1.420-1.429 1.430-1.439 1.440-1.449 1.450-1.459 1.460-1.469 1.470-1.499 1.500-1.599 1.600-1.699 1.730-1.739 1.740-1.749 1.750-1.799 For further details, please refer to ITU-T List of Recommendations. B-ISDN ATM LAYER
7、 SPECIFICATION Summary This Recommendation specifies ATM header bit assignments including ATM cell structure and the associated coding for both NNI and UNI, defines service primitives to be exchanged with upper and lower layers and with the ATM management entity, and specifies ATM protocol procedure
8、s for GFC. Source ITU-T Recommendation 1.361 was revised by ITU-T Study Group 13 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 26th of February 1999. Recommendation 1.361 (02/99) 1 FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized
9、Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on
10、a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is cov
11、ered by the procedure laid down in WTSC Resolution No. 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation the term recognized operating agency (ROA) includes any indi
12、vidual, company, corporation or governmental organization that operates a public correspondence service. The terms Administration, ROA and public correspondence are defined in the Constitution of the ITU (Geneva, 1992). INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the
13、 practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendati
14、on development process. As of the date of approval of this Recommendation, the ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and ar
15、e therefore strongly urged to consult the TSB patent database. O ITU 1999 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. 11 Recomme
16、ndation 1.361 (02/99) STD-ITU-T RECMN 1-3bL-ENGL L999 48b2591 ObbOb45 4TT CONTENTS Page 1 Introduction 2 Cell structure coding . 2.1 Cell structure 2.2 Cell header format and encoding at UNI 2.2.1 Pre-assigned values of the physical cell header 2.2.2 Generic Flow Control (GFC) field 2.2.3 Routing fi
17、eld (VPINCI) 2.2.4 Payload Type (PT) field 2.2.5 Cell Loss Priority (CLP) field . 2.3 Cell header format and encoding at NNI 2.2.6 Header Error Control (HEC) field . 2.3.1 Pre-assigned values of the cell header . 2.3.2 Routing field (VPINCI) 2.3.3 Payload Type (PT) field 2.3.4 Cell Loss Priority (CL
18、P) field . 2.3.5 Header Error Control (HEC) field . 2.4 Cell information field . 2.4.1 Pre-assigned values . 3 Service primitives . 3.1 Primitives exchanged with the upper layer . 3.1.1 Descrlptlon of prlmltlves . 3.1.2 Descriptions of parameters . 3.2 Primitives exchanged with the lower layer . . 3
19、.2.1 Description of pnmltlves 3.2.2 Description of parameter . 3.3 Primitives exchanged with ATM Management (ATMM) -entity 3.3.1 Description of primitives . 3.3.2 Description of parameters . . . 4 ATM protocol procedures 4.1 GFC protocol procedures . 4.1.1 GFC field assignment 4.1.2 GFC procedures .
20、 4.2 Layer management communication. . 1 1 2 2 3 5 6 6 6 7 7 9 9 10 10 10 10 10 10 10 11 Il 11 12 13 13 15 15 15 16 19 . Recommendation 1.361 (02/99) 111 Page 4.3 Layer management . 19 4.3.1 Fault management . 19 4.3.2 Performance management . 19 4.3.3 Configuration management . 19 4.3.4 Resource ma
21、nagement . 20 Annex A . Alphabetical list of abbreviations used in this Recommendation . 20 Annex B . SDL diagrams for GFC procedures . 21 Appendix I . Pre-assigned values of physical cell headers . 33 iv Recommendation 1.361 (02199) Recommendation 1.361 B-ISDN ATM LAYER SPECIFICATION (revised in 19
22、99) 1 Introduction This Recommendation specifically addresses: a) the cell structure and the ATM cell coding; b) the ATM protocol procedures. 2 Cell structure coding Two different coding schemes have been adopted: the UNI format and the NNI format. They are described in 2.2 and 2.3. 2.1 Cell structu
23、re The cell consists of a five-octet header and a 48-octet information field as shown in Figure 1. Bk8 7 6 5 4 3 2 1 (5 octets) Information field , (48 octets) , 53 I T1307450-96 Figure 1fl.361- Cell structure at the UNUNNI NOTE - The header will be sent first followed by the information field. When
24、 a field within the header is contained within a single octet, the lowest bit number of the field represents the lowest order value. When a field spans more than one octet, the order of bit values within each octet progressively decreases as the octet number increases; the lowest bit number associat
25、ed with the field represents the lowest order value. This leads to the following conventions: - bits within an octet are sent in decreasing order, starting with bit 8; - octets are sent in increasing order, starting with octet 1 ; - for all fields, the first bit sent is the Most Significant Bit (MSB
26、). 2.2 Cell header format and encoding at UNI The structure of the header is shown in Figure 2. The fields contained in the header and their encoding are described in the following subclauses. Recommendation 1.361 (02/99) 1 8 7 6 5 4 3 2 1 Octet GFC 3 VCI 2 VCI VPI 1 VPI VCI 4 PT I CLP HEC 5 CLP Cel
27、l Loss Priority GFC Generic Flow Control PT Payload Type HEC Header Error Control VPI Virtual Path Identifier VCI Virtual Channel Identifier Figure 2A.361- Header structure at UNI 2.2.1 Pre-assigned values of the physical cell header Physical cells are reserved for use by the Physical layer. These c
28、ells are not passed from the Physical layer to the ATM layer. Pre-assigned values of the cell header (to differentiate cells for the use of the ATM layer from cells for the use of the Physical layer) are given in Table 1. In the case of Physical cells, the bit in the location of the CLP indication i
29、s not used for the CLP mechanism as specified in 3.4.2.3.2A.150. All other values which are described in Tables 2 and 4 are for the use of the ATM layer. Table 1A.361 - Pre-assigned Physical cell header values (excluding the HEC field) Octet 1 OOOOPPP 1 00000000 00000000 PPPPOOOO Reserved for use of
30、 the Physical layer 0000000 1 00000000 00000000 00000000 Idle cell identification Octet 4 Octet 3 Octet 2 (Note) P Indicates the bit is available for use by the Physical layer. Values assigned to these bits have no meaning with respect to the fields occupying the corresponding bit positions at the A
31、TM layer. NOTE - Specific pre-assigned physical layer cell header values are given in Recommendation 1.432-series and in other Recommendations related to Physical layer (see Appendix I). 2.2.2 Generic Flow Control (GFC) field The GFC field contains 4 bits. I The following provides an overview of the
32、 GFC fnctions for the valid codings of the GFC field (see 4.1.1). Uncontrolled equipment will always set the GFC field to 0000. Coding of this field by controlling and controlled equipment is given in 4.1 .l. The controlled equipment default mode provides for a single queue for controlled ATM connec
33、tions and allows uncontrolled ATM connections. The two- queue model provides for two queues for controlled ATM connections and allows uncontrolled ATM connections. At any given instant of time, controlled equipment which may not have any controlled ATM connections active will continue to respond to
34、the HALT command. 2 Recommendation 1.361 (02/99) STD-ITU-T RECMN 1.3hl-ENGL L999 - 486259l 0660649 045 II In the direction from the controlling equipment to the controlled equipment, the GFC field is defined as follows: (When the GFC function is not used, the value of this field is 0000.) - The firs
35、t bit indicates HALT (bit set to l)NO-HALT(O). The HALT command stops the transmission towards the network of assigned ATM layer cells, including cells on uncontrolled ATM connections. In the case of controlled ATM connections, the credit counter(s) is(are) not modified by the HALT command. - The se
36、cond bit indicates: I in the default mode (1-queue model) mode, SET(l)/NULL(O) for the controlled ATM connections; in the 2-queue model, SET/NULL for the connections of Group A. The SET/NULL command applies only to controlled ATM connections. It sets the credit counter to its GO-VALUE. - The third b
37、it is set to O in the default mode. In the 2-queue model, it indicates SETNULL - The fourth bit is set to O at the SB and TB reference point. In the multiaccess UNI, it indicates for the connections of Group B. the GFC signal of the ATM layer cell controls the emission from the B-TE* identified by i
38、ts specific VPI value. In the direction from controlled equipment to controlling equipment, the GFC field is defined as follows: - The first bit is unused and set to O. - In the default mode, the second bit indicates to the controlling equipment if the cell belongs to the uncontrolled ATM connection
39、s (O), or to the controlled ATM connections (1). In the 2-queue model, it indicates if the cell belongs to the controlled ATM connections of Group A (1) or not (O). i - In the default mode, the third bit is unused and set to O. In the 2-queue model, it indicates if - The fourth bit indicates if the
40、equipment is controlled (1) or uncontrolled (O). the cell belongs to the controlled ATM connections of Group B (1) or not (O). 2.2.3 Routing field (VPINCI) Twenty-four bits are available for routing: 8 bits for Virtual Path Identifier (VPI) and 16 bits for Virtual Channel Identifier (VCI). Pre-assig
41、ned combinations of VPI and VCI values are shown in Table 2. Other pre-assigned values of VPI and VCI are for further study. The VCI value of zero is not available for user virtual channel identification. The number of bits of the VPI and VCI fields used for routing are established by negotiation be
42、tween the user and the network as described in 3.1.2.3/1.150. The bits within the VPI and VCI fields used for routing are allocated using the following rules: - The allocated bits of the VPI field will be contiguous. - The allocated bits of the VPI field will be the least significant bits of the VPI
43、 field - The allocated bits of the VCI field will be contiguous. - The allocated bits of the VCI field will be the least significant bits of the VCI field (beginning at bit 5 of octet 2). (beginning at bit 5 of octet 4). Recommendation 1.361 (02/99) 3 STD-ITU-T RECMN 1.3bL-ENGL 1999 4862591 Obb0650
44、867 M Table 2A.361- Combinations of pre-assigned VPI, VCI, PT1 and CLP values at UNI Use CLP PT1 VCI W1 (Note 8) Jnassigned cell Any VPI value nvalid O _“ other than O Jnassigned cell (Note 13) Meta-signalling (Note 1) :See Recommendation 1.3 1 1) Any VPI value 3eneral broadcast signalling Any VPI v
45、alue :See Recommendation 1.3 1 1) (Note 1) Point-to-point signalling Any VPI value :See Recommendation 1.3 11) (Note 1) Segment OAM F4 flow cell Any VPI value See Recommendation 1.6 1 O) End-to-end OAM F4 flow cell Any VPI value (See Recommendation 1.610) VP resource management cell Any VPI value (S
46、ee Recommendation 1.371) Reserved for future VP Any VPI value functions (Note 6) Reserved for future functions Any VPI value (Note 7) Reserved for private network use (Note 12) Any VPI value Any VPI value Reserved for future functions (Note 7) Segment OAM F5 flow cell (See Recommendation 1.6 10) Any
47、 VPI value functions Any VPI value Reserved for future VC (See Recommendation 1.371) Any VPI value VC Resource management cell (See Recommendation 1.610) Any VPI value End-to-end OAM F5 flow cell O B Any value O O Any value “_ O 1 C OAA (Note 5) 2 C OAA (Note 5) 5 C OAA (Note 5) 3 A OAO (Note 4) (No
48、te 11) 4 A OAO (Note 4) (Note 11) 6 A 110 (Note 9) 7 A OAA (Note 10) (Note 11) Any VCI value in the A OAA range 8 to 15 (Note 10) Any VCI value in the A OAA range 16 to 21 Any VCI value in the A OAA range 22 to 3 1 (Note IO) Any VCI value other than A 1 O0 O, 3,4,6 or 7 Any VCI value other than A 10
49、1 O, 3,4,6 or 7 Any VCI value other than A 110 O, 3,4, 6 or 7 Any VCI value other than A 111 O, 3,4,6 or 7 The GFC field is available for use with all of these combinations. A Indicates that the bit may be O or 1 and is available for use by the appropriate ATM layer function. B Indicates the bit is a “dont care“ bit. C Indicates the originating entity shall set the CLP bit to O. The value may be changed by the network. I I 4 Recommendation 1.361 (02199) - STD-ITU-T RECMN I-3bL-ENGL 1999 48b2591 ObbObSL 7T3 Table 2h.361- Combinations of
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