1、 Next Generation Corporate Networks (NGCN) - General ECMA TR/95 1stEdition / June 2008 Ecma International Rue du Rhne 114 CH-1204 Geneva T/F: +41 22 849 6000/01 www.ecma-international.org IW TR-095.doc 04/06/2008 14:32:00 Next Generation Corporate Networks (NGCN) - General Technical Report ECMA TR/9
2、5 1stEdition / June 2008 . Introduction This Ecma Technical Report is the first of a series of Ecma publications that explore IP-based enterprise communication involving Corporate telecommunication Networks (CNs) (also known as enterprise networks) and in particular Next Generation Corporate Network
3、s (NGCN). The series particularly focuses on inter-domain communication, including communication between parts of the same enterprise, between enterprises and between enterprises and carriers. This particular Ecma Technical Report provides general information on the subject, defines some architectur
4、al concepts, identifies various communication scenarios, and provides a framework in support of other publications that provide greater detail on particular topics. This Technical Report is based upon the practical experience of Ecma member companies and the results of their active and continuous pa
5、rticipation in the work of ISO/IEC JTC1, ITU-T, ETSI, IETF and other international and national standardization bodies. It represents a pragmatic and widely based consensus. In particular, Ecma acknowledges valuable input from experts in ETSI TISPAN. This Ecma Technical Report has been adopted by th
6、e General Assembly of June 2008. - i - Table of contents 1 Scope 1 2 References 1 3 Definitions 1 3.1 Corporate telecommunication Network (CN) (ETSI EG 201 017 10) 1 3.2 Domain 2 3.3 Enterprise network 2 3.4 Home server 2 3.5 Transport service provider (TSP) 2 3.6 Medium 2 3.7 Next Generation CN (NG
7、CN) 2 3.8 Next Generation Network (NGN) 2 3.9 Private network traffic 3 3.10 Public network traffic 3 3.11 Roaming 3 3.12 Roaming hub 3 3.13 Session service provider (SSP) 3 3.14 SIP intermediary 3 4 Abbreviations 3 5 Background 4 6 General concepts 5 6.1 Basic communication architecture 5 6.2 Sessi
8、on level architecture 7 6.2.1 Signalling using SIP 8 6.2.2 Media path 9 6.2.3 Example 9 6.3 Domains 10 6.4 Mobility 11 6.4.1 Roaming of enterprise users outside their home domain 11 6.4.2 Accommodating guest users on an NGCN 12 6.5 The hosting concept 12 6.5.1 Dedicated NGCN 14 6.5.2 Enterprise host
9、ed by a single public network infrastructure 14 - ii - 6.5.3 Enterprise hosted by multiple public network infrastructures 15 6.5.4 Enterprise hosted by a combination of enterprise infrastructure and a public network infrastructure 15 6.6 Private network traffic and public network traffic 16 6.7 Othe
10、r technical considerations 16 7 Scenarios for session-based communications 17 7.1 Session-based intra-domain communications 17 7.2 Session-based inter-domain communications within a single enterprise network 19 7.2.1 Communication between domains supported by the same infrastructure 19 7.2.2 Communi
11、cations between domains of an NGCN via a TSP 20 7.2.3 Communications between domains of an NGCN using private network traffic through a hosting NGN 20 7.2.4 Communications between domains of an NGCN using public network traffic through a public SSP such as an NGN 21 7.2.5 Communications between a de
12、dicated NGCN domain and a domain hosted by an NGN 21 7.2.6 Communications between a dedicated NGCN domain and a domain hosted by an NGN as private network traffic via an intermediate NGN domain 22 7.3 Session-based communication between two enterprises 22 7.3.1 Extension of enterprise network to inc
13、lude partner networks 22 7.3.2 Direct peering 22 7.3.3 Indirect peering 23 7.3.4 Third party assistance 24 7.3.5 Direct peering between two enterprises hosted by the same hosting enterprise infrastructure 25 7.4 Session-based communication with users of public networks 26 7.4.1 Communication between
14、 an NGCN user and an NGN public network user 26 7.4.2 Communication between an NGCN user and an NGN public network user with break-in or break-out function in the NGN 27 7.4.3 Communication between an NGCN user and a public network user of a remote NGN 27 7.4.4 Communication between an NGCN user and
15、 a public network user of a remote NGN with break-in or break-out function in the local NGN 27 7.4.5 Communication between an NGCN user and a public network user of a remote NGN with break-in or break-out function in the remote NGN 28 7.4.6 Communication between an NGCN user and a PSTN/ISDN user via
16、 an NGN 28 7.4.7 Communication between an enterprise user hosted by a public network infrastructure and a public network user of that same infrastructure 29 7.5 Session-based roaming 29 7.5.1 An NGCN user at a visited sub-domain of the NGCN 30 7.5.2 An NGCN user at a visited sub-domain of the NGCN u
17、sing private network traffic through an NGN 30 7.5.3 An NGCN user at a visited NGN 30 7.5.4 An NGCN user at a visited NGN using indirect roaming 31 7.5.5 An NGN-hosted enterprise user at a visited NGN 31 7.5.6 An NGN-hosted enterprise user at a visited NGCN 31 - iii - 8 NGN considerations 32 8.1 Sum
18、mary of scenarios involving NGN 32 8.1.1 Scenarios involving NGN as a TSP 32 8.1.2 Scenarios involving NGN as a SSP 32 8.1.3 Roaming scenarios involving NGN as a SSP 32 8.2 Interfacing NGCN to NGN 33 8.2.1 Subscription-based business trunking 33 8.2.2 Peering-based business trunking 33 8.2.3 Roaming
19、 33 9 Application considerations 33 10 Current standards and standardisation efforts 35 10.1 IETF Real-time Applications and Infrastructure (RAI) area 35 10.2 SIP Forum 35 10.3 ETSI TISPAN 35 10.4 3GPP 35 10.5 ITU-T Study Group 13 35 - 1 - 1 Scope This Ecma Technical Report is part of a series of pu
20、blications that provides an overview of IP-based enterprise communication involving Corporate telecommunication Networks (CNs) (also known as enterprise networks) and in particular Next Generation Corporate Networks (NGCN). The series particularly focuses on session level communication based on the
21、Session Initiation Protocol (SIP) 6, with an emphasis on inter-domain communication. This includes communication between parts of the same enterprise (on dedicated infrastructures and/or hosted), between enterprises and between enterprises and public networks. Key technical issues are investigated,
22、current standardisation work and gaps in this area are identified and a number of requirements are stated. This particular Technical Report provides general information on the subject, defines some architectural concepts, identifies various communication scenarios, and provides a framework in suppor
23、t of other publications that provide greater detail on particular topics. At the time of publication of this Technical Report, one further document in the series has been published, on the subject of identification and routing 3. The scope of this Technical Report is limited to communications with a
24、 real-time element, including voice, video, real-time text and instant messaging. Further details on mobility in an NGCN environment are to be found in ECMA TR/92 2. 2 References 1 ECMA-269 Services for Computer Supported Telecommunications Applications (CSTA) Phase III 2 ECMA TR/92 Corporate Teleco
25、mmunication Networks - Mobility for Enterprise Communication 3 ECMA TR/96 Next Generation Corporate Networks (NGCN) - Identification and Routing 4 ITU-T Recommendation H.248 Gateway control protocol 5 ITU-T Recommendation H.323 Packet-based multimedia communications systems 6 IETF RFC 3261 SIP: Sess
26、ion Initiation Protocol 7 IETF RFC 3550 RTP: A Transport Protocol for Real-Time Applications 8 IETF RFC 4566 SDP: Session Description Protocol 9 SIP Forum sf-adopted-twg-IP_PBX_SP_Interop-sibley-sipconnect “IP-PBX / Service Provider Interoperability - SIPConnect 1.0 Technical Recommendation“ 10 ETSI
27、 EG 201 017 Corporate Telecommunication Networks (CN); Standardization plan 11 ETSI TR 180 000 Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); NGN Terminology 12 IEEE 802.1x Port Based Network Access Control 3 Definitions For the purposes of this Te
28、chnical Report the following definitions apply: 3.1 Corporate telecommunication Network (CN) (ETSI EG 201 017 10) Telecommunication network serving a corporation, i.e. a single organization, an extended enterprise, or an industry application group as defined by the International Chamber of Commerce
29、(ICC). NOTE Sets of equipment Customer Premises Equipment (CPE) and/or Customer Premises Networks (CPN) are - 2 - typically located at geographically dispersed locations and are interconnected to provide networking services to a defined group of users. A CN can employ connection-oriented and connect
30、ionless technology. 3.2 Domain Session level capabilities within a single administrative area. NOTE A domain may or may not correspond to a DNS domain. 3.3 Enterprise network A CN comprising session level capabilities and optionally application layer capabilities hosted on one or more infrastructure
31、s. NOTE Infrastructures can include the enterprises own infrastructure (dedicated NGCN), the infrastructure of one or more hosting NGNs, the infrastructure of one or more hosting NGCNs or any combination of these. 3.4 Home server For a given user, as identified by a SIP address of record, the SIP in
32、termediary that contains registrar and proxy functionality in support of that user. NOTE It is therefore the SIP intermediary with which the users UAs register. 3.5 Transport service provider (TSP) A business or organisation separate from an enterprise that provides services for transporting data ba
33、sed on the use of IP at the network layer, thereby allowing the enterprise to communicate with entities outside the enterprise or with geographically dispersed parts of the enterprise. NOTE 1 Communication can but need not be via the public Internet. NOTE 2 A TSP should not intervene above the trans
34、port layer. This does not preclude a business or organisation that acts as a TSP also acting as the provider of higher level services, e.g., as an SSP. 3.6 Medium A given type of payload transported between session users (e.g., audio, video, text), separate from any signalling used for session estab
35、lishment. 3.7 Next Generation CN (NGCN) That part of an enterprise network that is not based on public network infrastructure, that is designed to take advantage of emerging IP-based communications solutions and that can have its own applications and service provisioning. NOTE. An NGCN can be an ent
36、ire enterprise network if none of that network is based on public network infrastructure. 3.8 Next Generation Network (NGN) The definition in 11 applies. NOTE. This defines an NGN as follows: “A Next Generation Network is a packet-based network able to provide services including Telecommunication Se
37、rvices and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies. It offers unrestricted access by users to different service providers. It supports generalized mobility which w
38、ill allow consistent and ubiquitous provision of services to users.“ It also goes on to list some fundamental aspects that characterise NGN. - 3 - 3.9 Private network traffic Signalling for session level communications that is handled according to rules specific to an enterprise network. 3.10 Public
39、 network traffic Signalling for session level communications that is handled according to rules for public networks. 3.11 Roaming The use of session capabilities of a visited domain to allow a user to access session level services at his home domain. NOTE 1 This usually requires a roaming agreement
40、between the operators of the domains concerned. NOTE 2 This definition of roaming reflects the concept of roaming as found in mobile telephone networks, for example. It does not encompass certain other common uses of the term, e.g., concerning transport service provision. 3.12 Roaming hub A network
41、or other entity with which an enterprise domain has a roaming agreement, allowing enterprise users to visit other domains that have a roaming agreement with the roaming hub but not directly with the enterprise domain. 3.13 Session service provider (SSP) A business or organisation separate from an en
42、terprise that provides communication capabilities at the session layer using SIP and thereby allows the enterprise to communicate using SIP with entities outside the enterprise or with geographically dispersed parts of the enterprise. 3.14 SIP intermediary Any intermediate entity involved either act
43、ively or passively in SIP signalling between two UAs, including but not limited to proxies, Back-to-Back User Agents (B2BUAs), Application Layer Gateways (ALGs) and Session Border Controllers (SBCs). 4 Abbreviations ALG Application Layer Gateway B2BUA Back-to-Back User Agent CN Corporate telecommuni
44、cation Network DNS Domain Name System IP Internet Protocol IPPBX IP Private Branch eXchange IPSEC Internet Protocol Security ISDN Integrated Services Digital Network LAN Local Area Network NAT Network Address Translator NGCN Next Generation Corporate Network NGN Next Generation Network PSTN Public S
45、witched Telephone Network QoS Quality of Service - 4 - RTP Real Time Protocol SBC Session Border Controller SDP Session Description Protocol SIP Session Initiation Protocol SRTP Secure Real Time Protocol SSP Session Service Provider TLS Transport Layer Security TSP Transport Service Provider UA User
46、 Agent UAC User Agent Client UAS User Agent Server URI Universal Resource Identifier WAN Wide Area Network 5 Background Many enterprises and other organisations require their own telecommunications capabilities to support their own internal communications as well as supporting communications with th
47、e outside world. This avoids incurring unnecessary charges and provides added value in terms of services and features available, integration with other enterprise applications, etc. These capabilities are provided through enterprise telecommunication networks (or corporate telecommunication networks
48、, CN, or simply enterprise networks). Many administrations do not apply the same licensing conditions or regulation to enterprise networks and their internal traffic as they do to public networks and their public network traffic. Many public networks also offer optional services to corporate custome
49、rs, such as hosted (Centrex) services and the leasing and maintenance of customer premises equipment. There has been a major evolution in enterprise telecommunications during the last few years. Prior to that, enterprise network were based on 64 kbit/s circuit-switched technology, which had synergy with corresponding technology deployed in public Integrated Services Digital Networks (ISDN) and traditional analogue services. Those enterprise networks primarily delivered a voice or telephony service to their users, although in principle they were ca
