1、ITU-T RECMNUQ.930 93 = qBb259L O588603 11b = INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 NETWORK LAYER Q.930 (03193) DIG ITAL SU BSCRI BER SIGNALLING SYSTEM NO. 1 (DSS 1) - ISDN USER-NETWORK INTERFACE LAYER 3
2、- GENERAL ASPECTS ITU-T Recommendation Q.930 (Previously “CCITT Recommendation”) ITU-T RECMN*Q-930 93 4b259L 0588604 052 = FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying tech
3、nical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups whic
4、h, in their turn, produce Recommendations on these topics. ITU-T Recommendation 4.930 was revised by the ITU-T Study Group XI (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU), th
5、e CCITT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of th
6、is Recommendation, no change has been made in the text to references containing the acronyms “CCITT, CCIR or ERB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 te
7、lecommunication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1994 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or me
8、chanical, including photocopying and microfilm, without permission in writing from the ITU. CONTENTS Page 1 General . 1 2 Structure of layer 3 Recommendations 2 Interface between layer 3 and the adjacent layers 3 2 Recommendation 4.930 (03/93) i ITU-T RECMN*d.930 93 m 4862591 0588606 925 m Recommend
9、ation Q.930 DIGITAL SUBSCRIBER SIGNALLING SYSTEM NO. 1 (DSS 1) - ISDN USER-NETWORK INTERFACE LAYER 3 - GENERAL ASPECTS (Mlaga-Torremolinos, 1984; modified at Helsinki, 1993) 1 General 1.1 Introduction This Recommendation describes in general terms the D-channel layer 3 functions and protocol employe
10、d across an ISDN user-network interface. Details are provided in Recommendations in the Q.930-Series and in the Q.950-Series. The term “layer 3” is a general term used in these Recommendations to refer to the procedures described in Recommendation 4.931 11 and in Recommendation Q.932 2. The term “la
11、yer 3” does not correspond to layer 3 of the OS1 protocol reference model or to layer 3 of the control plane of the ISDN protocol reference model. The layer 3 protocol provides the means to establish, maintain and terminate network connections across an ISDN between communicating application entitie
12、s. In addition, it provides generic procedures which may be used for the invocation and operation of supplementary services. The detailed description of the layer 3 protocol in Recommen- dation Q.931, Recommendation 4.932 and Recommendation Q.933 3 make use of the definition and terminology concepts
13、 of the ISDN protocol reference model given in Recommendation 1.320 4. Procedures for basic call, to support a range of bearer services and teleservices are described. Recommendation Q.93 1 contains procedures for circuit-mode and packet-mode bearer capabilities. Recommendation 4.933 contains proced
14、ures for frame-mode bearer capabilities. Recommendation 4.939 5 contains a detailed description of the coding of the compatibility information elements required to identify the various bearer services and teleservices. Recommendation 4.932 contains a number of generic protocols for the provision of
15、supplementary services. The application of the functional protocol of Recommendation 4.932 to the detailed operation of each individual supplementary service will be the subject for the Recommendations in the Q.950-Series. 1.2 Connection control by the user of an ISDN requires: a) application of lay
16、er 3 protocol for control of circuit-switched connections, packet-switched and/or frame- mode connections, in combination with; b) application of an appropriate data link layer service (supported by an appropriate physical layer service). Layer 3 provides to the user the functions associated with th
17、e establishment and operation of a network connection. Layer 3 makes invisible to the user how it utilizes underlying resources such as data link connections to provide a network connection. 1.3 Services provided by the data link layer Layer 3 utilizes functions and services provided by the data lin
18、k as defined in Recommendations 4.920 6 and 4.921 7. These services are summarized below: establishment of data link connections; a) b) error-protected transmission of data; c) re-establishment of data link connection (indicating loss of information). Recommendation Q.930 (03/93) 1 ITU-T RECMN+d.730
19、 73 = 4862593 0588b07 863 = 1.4 It is intended that the layer 3 protocol is fully symmetrical to enable direct user-to-user communication. In order to achieve this objective, several options are incorporated in Recommendation 4.931. They are described in Annex DlQ.931. Symmetry of the layer 3 protoc
20、ol 2 The following is the structure of the layer 3 Recommendations: Structure of layer 3 Recommendations 4.930 - ISDN user-network interface layer 3 - General aspects 4.931 - ISDN user-network interface layer 3 specification for basic call control 4.932 - Generic procedures for the control of ISDN s
21、upplementary services Q.933 - Specification for frame-mode basic call control Q.939 - Typical DSS 1 service indicator codings for ISDN telecommunications services Q.950 - Supplementary service protocols - Structure and general principles Further supplementary service Recommendations are described in
22、 Recommendation Q.950 8. 3 Interface between layer 3 and the adjacent layers 3.1 Overview of the interface between ISDN user-network interface layer 3 and the data link layer from the view point of the data link layer is given in UQ.920. Primitives and primitive procedures for this interface are spe
23、cified in 4/Q.921. Interface between layer 3 and data link layer 3.2 Interface to call control Both basic call and supplementary service protocols interface to call control. A general view of this structure is given in Figure 1. 2 Processing Basic supp. SE. Protocol Prutocol (Facility) (2.931) (2.93
24、1 Messages I I IAPD I I 1.m.431 I Exchange Call Processing supp. SE. Proiocd (Facilityj Basic Service Prdccd (Q.931) I Q.931 Messages 1.430/1.431 I T1143260-92/dOl FIGURE UQ.930 Modelling of basic and supplementary services Recommendation Q.930 (03/93) ITU-T RECMN*Q.930 93-k 4862593 0588608 7T8 3.3
25、See list at the end of Recommendation 4.93 1. Abbreviations used in Recommendations Q.930(1.450) and Q.931(1.451) References CCITT Recommendation ISDN user-network interface layer 3 specijcation for basic call control, Rec. Q.93 l(1.45 1). CCITT Recommendation Generic procedures for the control of I
26、SDN supplementary services, Rec. Q.932(1.452). CCITT Recommendation Digital subscriber Signalling System No. I (DSS 1) - Signalling specification for frame mode basic call control, Rec. 4.933. CCITT Recommendation ISDNprotocol reference model, Rec. 1.320. CCITT Recommendation Typical DSS 1 service i
27、ndicator codings for ISDN telecommunications services, Rec. 4.939. CCIT Recommendation ISDN user-network interface data link layer - General aspects, Rec. Q.920(1.440). CCITT Recommendation ISDN user-network inte$ace data link layer specijcation, Rec. 4.92 l(I.441). CCITT Recommendation Supplementary services protocols - Structure and general principles, Rec. 4.950. Recommendation Q.930 (03/93) 3
