1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T H.248 Sub-series Implementors Guide TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (23 October 2015) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMS Infrastructure of audiovisual services Communication procedures Implementors
2、 Guide for the H.248 Sub-series of Recommendations (“Media Gateway Control Protocol”) Implementors Guide for the H.248 Sub-series of Recommendations (2015-10) i Summary This document is a compilation of reported defects identified in the ITU-T H.248 sub-series of Recommendations currently in force.
3、It must be read in conjunction with the Recommendations to serve as an additional authoritative source of information for implementors. The changes, clarifications and corrections defined herein are expected to be included in future versions of affected H.248 sub-series Recommendations. This edition
4、 contains all updates submitted up to and including those at Study Group 16 meeting in Geneva, 12 - 23 October 2015 This Implementors Guide was approved by ITU-T Study Group 16 on 23 October 2015. NOTE The Implementors Guides for H.248.1 Version 1 and Version 2 are published as separate documents. (
5、ITU-T H.248.1 is currently in its version 3.) Implementors Guide for the H.248 Sub-series of Recommendations (2015-10) ii Change Log (All changes that were included in corrigenda, amendments or revisions to the Recommendations in the H.248 subseries are omitted here.) V1 (Geneva, 23 October 2015) Ne
6、w: H.248.1 Section 6.1 Usage of DOT in digitmaps 6.2 Updated ABNF reference 6.3 Reserve Properties clarifications H.248.9 Section 7.1 Updated ABNF reference H.248.40 Section 8.1 Packet types subject to detection logic H.248.53 Section 9.1 Rate policing clarifications H.248.69 Section 10.1 Superfluou
7、s reference H.248.80 Section 11.1 Updated reference H.248.83 Section 12.1 Incorrect reference H.248.87 Section 13.1 Updated reference Updated: None. Removed: None. Implementors Guide for the H.248 Sub-series of Recommendations (2015-10) iii Contact Information ITU-T Study Group 16 / Question 3/16 Ra
8、pporteur Christian Groves Australia Tel: +61 3 9391 3457 E-mail: Christian.G H.248 Sub-series Implementors Guide Editor Christian Groves Australia Tel: +61 3 9391 3457 E-mail: Christian.G Implementors Guide for the H.248 Sub-series of Recommendations (2015-10) iv Table of Contents Page 1 Scope 5 2 I
9、ntroduction 5 3 Defect Resolution Procedure . 5 4 References 6 5 Nomenclature . 6 6 Technical and Editorial Corrections to H.248.1 (03/2013) 7 6.1 Usage of DOT in digitmaps . 7 6.2 Updated ABNF reference 8 6.3 Reserve Properties clarifications . 8 7 Technical and Editorial Corrections to H.248.9 (12
10、/2009) 11 7.1 Updated ABNF reference 11 8 Technical and Editorial Corrections to H.248.40 (03/2013) 12 8.1 Packet types subject to detection logic 12 9 Technical and Editorial Corrections to H.248.53 (03/2009) 13 9.1 Rate policing clarifications 13 10 Technical and Editorial Corrections to H.248.69
11、(03/2009) 15 10.1 Superfluous reference 15 11 Technical and Editorial Corrections to H.248.80 (01/2014) 16 11.1 Updated reference 16 12 Technical and Editorial Corrections to H.248.83 (02/2012) 17 12.1 Incorrect reference . 17 13 Technical and Editorial Corrections to H.248.87 (01/2014) 19 13.1 Upda
12、ted reference 19 Annex: Defect Report Form for the H.248 Sub-series 21 Implementors Guide for the H.248 Sub-series of Recommendations (2015-10) 5 IMPLEMENTORS GUIDE FOR THE H.248 SUB-SERIES OF RECOMMENDATIONS 1 Scope This guide resolves defects in the following categories: editorial errors technical
13、 errors, such as omissions and inconsistencies ambiguities In addition, the Implementors Guide may include explanatory text found necessary as a result of interpretation difficulties apparent from the defect reports. This Guide will not address proposed additions, deletions, or modifications to the
14、Recommendations that are not strictly related to implementation difficulties in the above categories. Proposals for new features should be made through contributions to the ITU-T. 2 Introduction The H.248 Implementors Guide is a compilation of reported defects for all versions of the H.248.x sub-ser
15、ies of Recommendations, except H.248.1 Version 1 (03/2002) and H.248.1 Version 2 (05/2002) Corrigendum 1 (03/2004). For the defects in Version 1, see the H.248.1 Version 1 Implementors Guide. For the defects in Version 2, see the H.248.1 Version 2 Implementors Guide. In this edition of the Guide, re
16、ported defects identified as of 23 October 2015 are given for: H.248.1 (03/2013) H.248.9 (12/2009) H.248.40 (03/2013) H.248.53 (03/2009) H.248.69 (03/2009) H.248.80 (01/2014) H.248.83 (02/2012) H.248.87 (01/2014) The Guide must be read in conjunction with the H.248.x sub-series of Recommendations to
17、 serve as an additional source of information for implementors. The changes, clarifications and corrections defined herein are expected to be included in future versions of affected H.248.x Recommendations. 3 Defect Resolution Procedure Upon discovering technical defects with any components of the H
18、.248.x Sub-series Recommendations, please provide a written description directly to the editors of the affected Recommendations with a copy to the Q.3/16 Rapporteur. The template for a defect report is located at the end of the Guide. Contact information for these parties is included at the front of
19、 the document. Return contact information should also be supplied so a dialogue can be established to resolve the matter and an appropriate reply to the defect report can be conveyed. This defect resolution process is open to any interested party. Formal membership in the ITU is not required to part
20、icipate in this process. Implementors Guide for the H.248 Sub-series of Recommendations (2015-10) 6 4 References This document refers to the following H.248.x sub-series Recommendations: ITU-T H.248.1 Recommendation ITU-T H.248.1 (03/2013), Gateway Control Protocol. ITU-T H.248.9 Recommendation ITU-
21、T H.248.9 (12/2009), Gateway Control Protocol: Advanced media server packages. ITU-T H.248.40 Recommendation ITU-T H.248.40 (03/2013), Gateway control protocol: Application data inactivity detection package. ITU-T H.248.53 Recommendation ITU-T H.248.53 (03/2009), Gateway control protocol: Traffic ma
22、nagement packages. ITU-T H.248.69 Recommendation ITU-T H.248.69 (03/2009), Gateway control protocol: Packages for interworking between MSRP and H.248. ITU-T H.248.80 Recommendation ITU-T H.248.80 (01/2014), Gateway control protocol: Usage of the revised SDP offer/answer model with ITU-T H.248. ITU-T
23、 H.248.83 Recommendation ITU-T H.248.83 (02/2012), Gateway control protocol: Media gateway instance package. ITU-T H.248.87 Recommendation ITU-T H.248.87 (01/2014), Gateway control protocol: Guidelines on the use of ITU-T H.248 capabilities for performance monitoring in RTP networks in ITU-T H.248 p
24、rofiles. 5 Nomenclature In addition to traditional revision marks, the following marks and symbols are used to indicate to the reader how changes to the text of a Recommendation should be applied: Symbol Description Begin Correction Identifies the start of revision marked text based on extractions f
25、rom the published Recommendations affected by the correction being described. End Correction Identifies the end of revision marked text based on extractions from the published Recommendations affected by the correction being described. . Indicates that the portion of the Recommendation between the t
26、ext appearing before and after this symbol has remained unaffected by the correction being described and has been omitted for brevity. - SPECIAL INSTRUCTIONS - instructions Indicates a set of special editing instructions to be followed. Implementors Guide for the H.248 Sub-series of Recommendations
27、(2015-10) 7 6 Technical and Editorial Corrections to H.248.1 (03/2013) 6.1 Usage of DOT in digitmaps Issue: Digit maps allow the specification of a “.” DOT in a digit map. This DOT indicates that the preceding element may be repeated zero or more times. The example in 7.1.14.9/ITU-T H.248.1 shows it
28、s usage: 9011 + up to 15 digits is denoted by “9011x.” However there has been some confusion over whether the preceding element to the DOT has to be matched for a successful digit map completion. I.e. for the above example is “9011” a successful match? This question has been posted to the IETF Megac
29、o mailing list on two previous occasions previously: (29/09/2008, “Megaco question about interpretation of dot in a digitmap”) and (16/05/2007, “DOT in H.248 Digit map syntax”). The reply on both those occasions was the key word is “repetitions” and that there must be at least occurrence of the prec
30、eding element. I.e. In the above example “90112” would result in a successful match but “9011” would not. Reference: AVD-4448 Begin Correction 7.1.14.3 DigitMap syntax The formal syntax of the DigitMap is described by the DigitMap rule in the formal syntax description of the protocol (see Annexes A
31、and B). A DigitMap, according to this syntax, is defined either by a string or by a list of strings. Each string in the list is an alternative event sequence, specified either as a sequence of DigitMap symbols or as a regular expression of DigitMap symbols. These DigitMap symbols, the digits “0“ thr
32、ough “9“ and letters “A“ through a maximum value depending on the signalling system concerned, but never exceeding “K“, correspond to specified events within a package which has been designated in the Events Descriptor on the termination to which the DigitMap is being applied. (The mapping between e
33、vents and DigitMap symbols is defined in the documentation for packages associated with channel-associated signalling systems such as DTMF, MF, or R2. Digits “0“ through “9“ must be mapped to the corresponding digit events within the signalling system concerned. Letters should be allocated in logica
34、l fashion, facilitating the use of range notation for alternative events.) The letter “x“ is used as a wildcard, designating any event corresponding to symbols in the range “0“-“9“. The string may also contain explicit ranges and, more generally, explicit sets of symbols, designating alternative eve
35、nts any one of which satisfies that position of the DigitMap. Finally, the dot symbol “.“ stands for one occurrence and zero or more repetitions of the event selector (event, range of events, set of alternative events, or wildcard) that precedes it. As a consequence of the third timing rule above, i
36、nter-event timing while matching a terminal dot symbol uses the short timer by default. In addition to these event symbols, the string may contain “S“ and “L“ inter-event timing specifiers and the “Z“ duration modifier. “S“ and “L“ respectively indicate that the MG should use the short (S) timer or
37、the long (L) timer for subsequent events, overriding the timing rules described above. If an explicit timing specifier is in effect in one alternative event sequence, but none is given in any other candidate alternative, the timer value set by the explicit timing specifier must be used. If all seque
38、nces with explicit timing controls are dropped from the candidate set, timing reverts to the default rules given above. If used inside a range notation, the S and L specifiers shall be ignored. Finally, if conflicting timing specifiers are in effect in different alternative sequences, the long timer
39、 shall be used. Implementors Guide for the H.248 Sub-series of Recommendations (2015-10) 8 A “Z“ designates a long duration event: placed in front of the symbol(s) designating the event(s) which satisfy a given digit position, it indicates that that position is satisfied only if the duration of the
40、event exceeds the long-duration threshold. The value of this threshold is assumed to be provisioned in the MG, but, like the T, L, and S timers, can be overridden by specification within the DigitMap. If the Z specifier is not followed by a digit (0-9 or A-K), then the MG shall reject the digitmap a
41、s invalid procedure. When used in a range notation, the Z specifier applies solely to the immediately following digit. When used immediately prior to a range, the Z modifier applies to all digits in the range (thereby requiring a match in the range to be long duration). End Correction 6.2 Updated AB
42、NF reference Issue: H.248.1 contains a reference to RFC2234 for ABNF syntax. This RFC has been obsoleted. The latest definition of ABNF is RFC 5234 which is also known as STD 68. The updates to the RFC are mainly with regards to its use with email. There are no changes that effect H.248 encoding. Re
43、ference: Discussions resulting from H.248.66 (COM16-C.351). Begin Correction 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 editions indicate
44、d 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 valid ITU-T Recom
45、mendations 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. IETF RFC 2234 IETF RFC 2234 (1997), Augmented BNF for Syntax Specifications: ABNF. IETF RFC 5234 IETF RFC 5234 (2008), Augmented BNF
46、for Syntax Specifications: ABNF. End Correction NOTE For brevity, the changes to the references inside H.248.1 have not been included. The references to IETF RFC 2234 in clauses 7.2.10, A.3 and B.2 shall be changed to IETF RFC 5234. 6.3 Reserve Properties clarifications Issue: There has been some co
47、nfusion with regards to the behaviour of property overspecification and the use of ReserveValue and ReserveGroup. Clarifying text is added to clause 7.1.7 on the relation between the concepts. The note in clause 7.1.8.2.3.2 is related to ReserveGroup=True and thus should be placed in clause 7.1.8.2.
48、3.3. Reference: COM16-C.686 Implementors Guide for the H.248 Sub-series of Recommendations (2015-10) 9 Begin Correction 7.1.7 LocalControl Descriptor a) Overview The LocalControl Descriptor contains the Mode Property, the ReserveGroup and ReserveValue Properties and properties of a termination (defi
49、ned in packages) that are stream specific, and are of interest between the MG and the MGC. Values of properties may be specified as in clause 7.1.1. b) Mode Property (for directionality control) The allowed values for the Mode Property are “SendOnly“, “RecvOnly“, “SendRecv“, “Inactive“ and “LoopBack“. “SendOnly“, “RecvOnly“ and “LoopBack“ are with respect to the exterior of the context, so that, for example, a stream set to mode = “SendOnly“ does not pass received
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