1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T H.460.3TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2002) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSSupplementary services for multimedia Circuit maps within H.323 systems ITU-T Recommendation H.460.3 ITU-T H-SERIES RECOMMENDATIONS AUDIOVISUAL AN
2、D MULTIMEDIA SYSTEMS CHARACTERISTICS OF VISUAL TELEPHONE SYSTEMS H.100H.199 INFRASTRUCTURE OF AUDIOVISUAL SERVICES General H.200H.219 Transmission multiplexing and synchronization H.220H.229 Systems aspects H.230H.239 Communication procedures H.240H.259 Coding of moving video H.260H.279 Related syst
3、ems aspects H.280H.299 SYSTEMS AND TERMINAL EQUIPMENT FOR AUDIOVISUAL SERVICES H.300H.399 SUPPLEMENTARY SERVICES FOR MULTIMEDIA H.450H.499 MOBILITY AND COLLABORATION PROCEDURES Overview of Mobility and Collaboration, definitions, protocols and procedures H.500H.509 Mobility for H-Series multimedia s
4、ystems and services H.510H.519 Mobile multimedia collaboration applications and services H.520H.529 Security for mobile multimedia systems and services H.530H.539 Security for mobile multimedia collaboration applications and services H.540H.549 Mobility interworking procedures H.550H.559 Mobile mult
5、imedia collaboration inter-working procedures H.560H.569 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. H.460.3 (11/2002) i ITU-T Recommendation H.460.3 Circuit maps within H.323 systems Summary This Recommendation specifies a mechanism that allows a PSTN H.323 Ga
6、teway to report circuit service and usage status to a Gatekeeper using the circuit status map parameter. Individual PSTN circuits on the Gateway may be taken out-of-service by a provisioning command from service personnel or when an ISUP out-of-service or blocking message is received from the adjace
7、nt PSTN switch. In this case, the Gateway will be able to report the current circuit status to the Gatekeeper so that it may select only from available circuits for outgoing calls through that Gateway. Source ITU-T Recommendation H.460.3 was prepared by ITU-T Study Group 16 (2001-2004) and approved
8、under the WTSA Resolution 1 procedure on 29 November 2002. ii ITU-T Rec. H.460.3 (11/2002) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent org
9、an of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the
10、topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are
11、prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the
12、 practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. 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 Recommendation d
13、evelopment process. As of the date of approval of this Recommendation, ITU had not 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 are th
14、erefore strongly urged to consult the TSB patent database. ITU 2003 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. H.460.3 (11/2002) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Abbreviations 1 4 C
15、apability advertisement 2 5 Circuit Status report 2 6 Circuit Status Map parameter . 3 7 Circuit Status Map ASN.1 definition . 3 8 Description of ASN.1 types and fields . 4 ITU-T Rec. H.460.3 (11/2002) 1 ITU-T Recommendation H.460.3 Circuit maps within H.323 systems 1 Scope H.323 provides the abilit
16、y for a Gateway to report call capacity information in the callCapacity structure to a Gatekeeper to support routing of calls to that Gateway. The H.323 destinationCircuitId field as defined in ITU-T Rec. H.225.0 provided the means for a Gatekeeper to select a trunk group and circuit on a Gateway fo
17、r the outgoing call through that Gateway. However, the service state of individual PSTN circuits in trunk groups on a Gateway cannot be reported to the Gatekeeper. This means that the Gatekeeper cannot do proper circuit selection because it does not know the service state of circuits on the Gateway.
18、 Individual PSTN circuits on the gateway may be taken out-of-service by a provisioning command from service personnel, or when an ISUP out-of-service or blocking message is received from the adjacent PSTN switch. In this case, the Gatekeeper will route the call to the Gateway because it knows that c
19、ircuits are available (from callCapacity) on that Gateway, but not which circuits are in-service. When this occurs, the call will be rejected by the Gateway. This consumes network resources unnecessarily and will potentially increase post-dial delay. To solve the problem, this Recommendation provide
20、s the means for a Gateway to send circuit service state and usage status to a Gatekeeper. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the edit
21、ions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently vali
22、d ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. 1 ITU-T Recommendation H.323 (2000), Packet-based multimedia communications systems. 2 ITU-T Recommendation H.225.0 (200
23、0), Call signalling protocols and media stream packetization for packet-based multimedia communication systems. 3 ITU-T Recommendation Q.931 (1998), ISDN user-network interface layer 3 specification for basic call control. 3 Abbreviations This Recommendation uses the following abbreviations: ISUP IS
24、DN User Part PER Packed Encoding Rules RAS Registration, Admission and Status RCF Registration Confirmation 2 ITU-T Rec. H.460.3 (11/2002) 4 Capability advertisement A Gatekeeper signals its support for the capability to accept circuit service and usage status notifications from a Gateway by adverti
25、sing the capability in the featureSet.supportedFeatures field of the RCF message. The capability is indicated with the feature identifier shown in Table 1 as a supportedFeatures element and without parameters. 5 Circuit Status report A PSTN H.323 Gateway may report circuit service and usage status t
26、o a Gatekeeper using the circuit status parameter. The circuit status may be reported when a Gateway registers with the Gatekeeper, when circuit service state changes occur as a result of maintenance actions on the part of operations personnel, or when an ISUP Blocking message is received. A Gateway
27、 may report its circuit status to a Gatekeeper in H.225.0 RAS and call signalling messages. The Circuit Status Map parameter is transported as follows in the H.225.0 RAS and call signalling (Q.931) messages using the generic extensibility framework: When sending the Circuit Status Map parameter in t
28、he call signalling messages, the CircuitStatus shall be coded in the genericData parameter in the H.225.0 H323-UU-PDU in the User-user Information Element. When sending the Circuit Status Map parameter in the RAS messages, the CircuitStatus shall be coded in the genericData parameter in the request
29、parameter of the H.225.0 RasMessage. The genericData parameter indicates the circuitStatus feature and contains a circuitStatus parameter. If there are a large number of circuits on a Gateway the circuit status may be sent in several H.225.0 messages. Table 1 defines the Circuit Status feature. Tabl
30、e 1/H.460.3 Report of Circuit Status from a gateway to a gatekeeper Feature name: Circuit Status Feature Description: This feature allows an H.323 Gateway to report circuit service and usage status to a Gatekeeper. Feature identifier type: Standard Feature identifier value: 3 ITU-T Rec. H.460.3 (11/
31、2002) 3 6 Circuit Status Map parameter Table 2 defines the Circuit Status Map parameter. Table 2/H.460.3 Circuit Status Map parameter Parameter name: Circuit Status Map Parameter description: This is the data sent in H.225.0 RAS and Call Signalling messages to indicate circuit status. The content is
32、 a raw field consisting of the ASN.1 PER encoded CircuitStatusMap as specified in the ASN.1 below. Parameter identifier type: Standard Parameter identifier value: 1 Parameter type: Raw Parameter cardinality: Once and only once 7 Circuit Status Map ASN.1 definition The Circuit Status Map definition u
33、sed within the GenericData is shown below. CIRCUIT-STATUS-MAP DEFINITIONS AUTOMATIC TAGS := BEGIN IMPORTS CircuitIdentifier FROM H323-MESSAGES; CircuitStatus := SEQUENCE - root for Circuit Status Map ASN.1 circuitStatusMap SEQUENCE OF CircuitStatusMap OPTIONAL, . CircuitStatusMap := SEQUENCE statusT
34、ype CircuitStatusType, baseCircuitID CircuitIdentifier, range INTEGER (04095), status OCTET STRING, . CircuitStatusType := CHOICE serviceStatus NULL, - status: 0 = out-of-service, 1 = in-service busyStatus NULL, - status: 0 = free, 1 = in-use . END 4 ITU-T Rec. H.460.3 (11/2002) 8 Description of ASN
35、.1 types and fields CircuitStatusMap The CircuitStatusMap consists of a statusType field, a baseCircuitId field, a range field and a status field: a) statusType This is the type of status represented by the following status field. This includes serviceStatus that indicates whether the circuit is ava
36、ilable for service and busyStatus that indicates whether the circuit is currently being used for a connection. b) baseCircuitId This identifies the first circuit to which the range of status bits contained in the status field applies. c) range The number represented by the range code + 1 indicates t
37、he range of circuits affected by the CircuitStatusMap. This is in the range from 0 to 4095. d) status The status field contains from 0 to 4096 status bits numbered from 0 to 4095. Status bit 0 is located in the most significant bit position of the first status field octet. Other status bits follow i
38、n numerical order. The number of relevant status bits in a given status field is equal to range + 1. Each status bit is associated with a circuit such that status bit n is associated with circuit m + n, where m is the circuit identified in the baseCircuitId field. If the statusType indicates service
39、Status the circuit status bits are coded as follows: 0 out-of-service; 1 in-service. If the statusType indicates busyStatus the circuit status bits are coded as follows: 0 free; 1 in-use. Printed in Switzerland Geneva, 2003 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T S
40、eries B Means of expression: definitions, symbols, classification Series C General telecommunication statistics Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series G Tra
41、nsmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services digital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Co
42、nstruction, installation and protection of cables and other elements of outside plant Series M TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits Series N Maintenance: international sound programme and television transmissio
43、n circuits Series O Specifications of measuring equipment Series P Telephone transmission quality, telephone installations, local line networks Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks and open system communications Series Y Global information infrastructure and Internet protocol aspects Series Z Languages and general software aspects for telecommunication systems
