1、 International Telecommunication Union ITU-T H.248.79TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (02/2012) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSInfrastructure of audiovisual services Communication procedures Gateway control protocol: Guidelines for packet-based streams Recommendation ITU-
2、T H.248.79 ITU-T H-SERIES RECOMMENDATIONS AUDIOVISUAL AND 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
3、.240H.259Coding of moving video H.260H.279 Related systems aspects H.280H.299 Systems and terminal equipment for audiovisual services H.300H.349 Directory services architecture for audiovisual and multimedia services H.350H.359 Quality of service architecture for audiovisual and multimedia services
4、H.360H.369 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 systems and services H.510H.519 Mobile multimedia collaboration applications and
5、 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 multimedia collaboration inter-working procedures H.560H.569 BROADBAND, TRIPLE-PLAY
6、 AND ADVANCED MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 Advanced multimedia services and applications H.620H.629 Ubiquitous sensor network applications and Internet of Things H.640H.649 IPTV MULTIMEDIA SERVICES AND APPLICATIONS FOR IPTV General aspects H.700H.719 IPTV te
7、rminal devices H.720H.729 IPTV middleware H.730H.739 IPTV application event handling H.740H.749 IPTV metadata H.750H.759 IPTV multimedia application frameworks H.760H.769 IPTV service discovery up to consumption H.770H.779 For further details, please refer to the list of ITU-T Recommendations. Rec.
8、ITU-T H.248.79 (02/2012) i Recommendation ITU-T H.248.79 Gateway control protocol: Guidelines for packet-based streams Summary Recommendation ITU-T H.248.79 defines guidelines for handling ITU-T H.248 Streams that use a packet-based network as their underlying bearer technology. It describes how inc
9、oming packets to the media gateway (MG) are assigned to a specific combination of Stream, Termination and Context. Furthermore, it describes the order of the different operations that are applied to incoming and outgoing packets. This Recommendation does not define any new protocol syntax for ITU-T
10、H.248. History Edition Recommendation Approval Study Group 1.0 ITU-T H.248.79 2012-02-13 16 ii Rec. ITU-T H.248.79 (02/2012) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologie
11、s (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ 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 Telecommunic
12、ation Standardization Assembly (WTSA), which meets every four years, establishes the 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
13、information technology which fall within ITU-Ts purview, the necessary standards are 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
14、 agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or
15、 some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice
16、 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 developmen
17、t process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore stron
18、gly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2012 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T H.248.79 (02/2012) iii Table of Contents Page 1 Scope 1 2 Refere
19、nces. 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Term defined in this Recommendation 2 4 Abbreviations any acronyms 3 5 Conventions 4 6 Classification of packets into streams. 4 6.1 Overview 4 6.2 Lookup keys based on the local and remote descriptors 5 6.3 Lookup keys based on ITU-T H.248 P
20、roperties . 7 6.4 Lookup keys based on the termination type and TerminationID . 7 6.5 Overlapping classification rules . 7 6.6 Post-classification filtering . 7 6.7 Special consideration for ICMP packets 8 7 Ordering of operations 9 7.1 Assigning operations to protocol layers . 9 7.2 Ordering of ope
21、rations within a layer . 11 7.3 Policy rule based description of packet operations 12 8 Processing costs between primary and secondary operations on packets (like for measurements) 13 8.1 Principal areas of operations on packets 13 8.2 Processing costs 14 9 Filtering of TCP/IP traffic 15 9.1 Overvie
22、w TCP and IP filter types . 15 9.2 TCP/IP filter terms . 16 Bibliography. 17 Rec. ITU-T H.248.79 (02/2012) 1 Recommendation ITU-T H.248.79 Gateway control protocol: Guidelines for packet-based streams 1 Scope This Recommendation defines guidelines for handling ITU-T H.248 Streams that use a packet-b
23、ased network as their underlying bearer technology. Two significant points are covered by the guidelines: 1) How packets incoming into the MG are classified to a specific combination of Stream, Termination and Context. 2) In what order different operations (usually controlled by different packages)
24、are applied to incoming and outgoing packets. Furthermore, this Recommendation: 3) Provides qualitative statements concerning generic processing costs on packet handling. 4) Discusses in more detail the classification and filtering of Transmission Control Protocol (TCP)/Internet Protocol (IP) traffi
25、c. ITU-T H.248.79 relates to other ITU-T H.248.x-series Recommendations on packet processing as follows. Packet classification rules (clause 6), packet filtering rules (e.g., clause 9 and ITU-T H.248.43), packet address adaptation rules ITU-T H.248.37, packet marking rules ITU-T H.248.52, packet/tra
26、ffic policing rules (ITU-T H.248.53, ITU-T H.248.76) and packet measurement rules (e.g., clause 8 and ITU-T H.248.61) are related to this Recommendation. Other packet processing rules may also be applicable. 2 References The following ITU-T Recommendations and other references contain provisions whi
27、ch, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of a
28、pplying the most recent edition of the Recommendations and other references listed below. A list of the currently valid 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. IT
29、U-T H.248.1 Recommendation ITU-T H.248.1 (2005) Gateway control protocol: Version 3, and its amendments. ITU-T H.248.37 Recommendation ITU-T H.248.37 (2008), Gateway control protocol: IP NAPT traversal package. ITU-T H.248.39 Recommendation ITU-T H.248.39 (2006), Gateway control protocol: H.248 SDP
30、parameter identification and wildcarding. ITU-T H.248.43 Recommendation ITU-T H.248.43 (2008), Gateway control protocol: Packages for gate management and gate control. ITU-T H.248.52 Recommendation ITU-T H.248.52 (2008), Gateway control protocol: QoS support packages. ITU-T H.248.53 Recommendation I
31、TU-T H.248.53 (2009), Gateway control protocol: Traffic management packages. ITU-T H.248.58 Recommendation ITU-T H.248.58 (2008), Gateway control protocol: Packages for application level H.248 statistics. 2 Rec. ITU-T H.248.79 (02/2012) ITU-T H.248.61 Recommendation ITU-T H.248.61 (2009), Gateway co
32、ntrol protocol: Packages for network level H.248 statistics. ITU-T H.248.64 Recommendation ITU-T H.248.64 (2009), Gateway control protocol: IP router packages. ITU-T H.248.76 Recommendation ITU-T H.248.76 (2010), Gateway control protocol: Filter group package and guidelines. ITU-T X.200 Recommendati
33、on ITU-T X.200 (1994), Information technology Open Systems Interconnection Basic Reference Model: The basic model. ITU-T Y.2011 Recommendation ITU-T Y.2011 (2004), General principles and general reference model for Next Generation Networks. IETF RFC 791 IETF RFC 791 (1981), Internet Protocol. IETF R
34、FC 792 IETF RFC 792 (1981), Internet Control Message Protocol. IETF RFC 1122 IETF RFC 1122 (1989), Requirements for Internet Hosts Communication Layers. IETF RFC 1123 IETF RFC 1123 (1989), Requirements for Internet Hosts - Application and Support. IETF RFC 1812 IETF RFC 1812 (1995), Requirements for
35、 IP Version 4 Routers. IETF RFC 4443 IETF RFC 4443 (2006), Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification. IETF RFC 4566 IETF RFC 4566 (2006), SDP: Session Description Protocol. IETF RFC 4884 IETF RFC 4884 (2007), Extended ICMP to Support Multi-Pa
36、rt Messages. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 filter ITU-T H.248.43: A set of terms and/or criteria used for the purpose of separating or categorizing. This is accomplished via single- or multi-field matching of traffic h
37、eader and/or payload data. “Filters“ are often manipulated and used in network operation and policy. A filter rule is a specific policy rule. In the ITU-T H.248 context, packet filters specify the criteria for matching a pattern to distinguish separable classes of traffic. Filters are only related t
38、o ephemeral terminations. Filter rules are defined on the basis of ITU-T H.248 properties. NOTE 1 This filter definition implies the concept of filter actions, besides filter conditions. 3.1.2 lookup key ITU-T H.248.61: Flow identifier elements that can be used for packet classification with regard
39、to ITU-T H.248 Context delivery. NOTE 2 The embedded terms, flow identifier and flow are defined by clauses 3.1.2 and 3.1.1 in ITU-T H.248.61. 3.2 Term defined in this Recommendation This Recommendation defines the following term: 3.2.1 classification rule: The rule used to match packets with a spec
40、ific Stream. The protocol elements used in rule conditions are called “lookup keys“. Rec. ITU-T H.248.79 (02/2012) 3 4 Abbreviations any acronyms This Recommendation uses the following abbreviations and acronyms: AMR Adaptive Multi-Rate B2BIH Back-to-back Internet protocol Host BRM Basic Reference M
41、odel CPU Central Processing Unit DA Destination Address ICMP Internet Control Message Protocol IP Internet Protocol IPR Internet Protocol Router IPv4 IP Version 4 IPv6 IP Version 6 L2 Layer 2 L3 Layer 3 L3HI Layer 3 Header Inspection L4 Layer 4 L4HI Layer 4 Header Inspection LD Local Descriptor LSP
42、Label Switch Path MG Media Gateway MGC Media Gateway Controller MSRP Message Session Relay Protocol NAT Network Address Translator OSI Open Systems Interconnection PDU Protocol Data Unit QoS Quality of Service RD Remote Descriptor RFC Request For Comment RTP Real-time Transport Protocol SA Source Ad
43、dress SDP Session Description Protocol TCAM Ternary Content-Addressable Memory TCP Transmission Control Protocol TLS Transport Layer Security ToS Type of Service 4 Rec. ITU-T H.248.79 (02/2012) UDP User Datagram Protocol UDPTL UDP Transport Layer VLAN Virtual Local Area Network 5 Conventions None. 6
44、 Classification of packets into streams 6.1 Overview 6.1.1 Terminations with one or multiple streams For the media-gateway to operate correctly, it must be able to classify and deliver each incoming packet into a single, specific ITU-T H.248 stream. Once this classification is made, the packet is al
45、so associated with the termination hosting the stream, and the context holding the termination. The rule used to match packets with a specific stream is referred as the streams classification rule. This rule is based on information that can appear in one or more of the following protocol elements: 1
46、) The contents of the streams local and remote descriptors. 2) Properties appearing in the streams LocalControl descriptor. 3) The type and TerminationID of the termination hosting the stream. 4) Properties appearing in the TerminationState descriptor of the termination hosting the stream. 5) Proper
47、ties appearing in the ContextAttributes descriptor of the context holding the streams termination. The set of protocol elements used in the creation of the classification rule are referred to as lookup keys. Some ITU-T H.248 packages mandate or prohibit the use of certain elements as lookup keys. An
48、 MG implementing such a package shall follow these requirements when creating classification rules. For most protocol elements, however, there is no normative requirement concerning classification rules. Whether each element is used as a lookup key is therefore dependant on the particular use cases
49、or the employed ITU-T H.248 profile. For example, certain use cases may call for the MG to consider a source-filter attribute (see b-IETF RFC 4570 appearing in a session description protocol (SDP) local descriptor as a lookup key), while other use cases may require that such an attribute be ignored. Usually, a logical AND operation is assumed between all the single conditions (with their lookup keys) of the overall compound condition of a classification rule, i.e., a pac
