1、 ATIS-1000018 NGN ARCHITECTURE TECHNICAL REPORT The Alliance for Telecommunication Industry Solutions (ATIS) is a technical planning and standards development organization that is committed to rapidly developing and promoting technical and operations standards for the communications and related info
2、rmation technologies industry worldwide using a pragmatic, flexible and open approach. Over 1,100 participants from over 300 communications companies are active in ATIS 22 industry committees and its Incubator Solutions Program. Notice of Disclaimer Technical Specification Group Services and Systems
3、 Aspects, Network Architecture (Release 6).11This document is available from the Third Generation Partnership Project (3GPP) at ATIS-1000018 2 2 3ETSI ES 282 001 V1.1.1 (2005-08), Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN), NGN Functional Archit
4、ecture Release 1.23 ITU-T Recommendation Y.2012, Functional Requirements and Architecture of the NGN.34 ITU-T Recommendation Y.2001, General Overview of NGN.35 ITU-T Recommendation Y.2011, General Principles and General Reference Model for Next Generation Networks.36 IETF RFC 3261, Session Initiatio
5、n Protocol.47 ITU-T Recommendation H.248, Gate Control Protocol.38 IETF RFC 3588, Diameter Base Protocol.49 IETF RFC 2748, Common Open Policy Service (COPS).43 DEFINITIONS, ACRONYMS, Packet filtering based firewall; Traffic classification and marking; Traffic policing and shaping; Network address an
6、d port translation,; Media Relay (i.e., media latching) for NAT traversal; and Collecting and reporting resource Usage information (e.g., start-time, end-time, octets of sent data). As one key injection node for support of dynamic Quality of Service (QoS) control, NAPT/FW control, and NAT traversal,
7、 the A-BGF performs the above functions on an IP flow under the control of the PDF. 3.1.2 Application Server (AS): An Application Server (AS) executes service logic associated with value-added services. The AS can reside either in the users home network or in a third party location. . 2This document
8、 is available from the European Telecommunications Standards Institute (ETSI). 3This document is available from the International Telecommunications Union. 4This document is available from the Internet Engineering Task Force (IETF). ATIS-1000018 3 The third party could be a network or simply a stand
9、-alone AS. The AS provides enhanced and intelligent services to subscribers. 3.1.3 Breakout Gateway Control Function (BGCF): A BGCF identifies the network that will be used for connecting IP sessions to the PSTN. If the S-CSCF determines that a destination address is in the PSTN, the S-CSCF forwards
10、 the session request to a BGCF. Based on further analysis of the destination address, and on agreements between Service Providers for PSTN termination, the BGCF will either select a local MGCF to perform the termination or will forward the request to a BGCF in another Service Providers network who w
11、ill select the MGCF to perform the termination. 3.1.4 Call Session Control Function (CSCF): There are three variants of the CSCF: 1) Proxy CSCF (P-CSCF); 2) Serving CSCF (S-CSCF); and 3) Interrogating CSCF (I-CSCF). The P-CSCF is the first point of contact and the control point for the User Equipmen
12、t (UE) within the Service Provider network. It forwards session requests from the UE to the S-CSCF and may not maintain session states. The S-CSCF has access to the user subscription data and actually handles the session request. It maintains session states. The I-CSCF is the first contact point wit
13、hin a Service Provider network for all incoming session requests from another Service Provider. These requests can be for a subscriber of the Service Provider, or for a roaming subscriber currently located within the Service Providers service area. 3.1.5 Functional architecture: The functional archi
14、tecture consists of a set of functional entities. These functional entities describe the structure of a NGN and are separated by reference points and thus they define the distribution of functions. These functional entities can be used to describe a set of reference configurations. These reference c
15、onfigurations identify which of the reference points are visible at boundaries of equipment implementations and between administrative domains. 3.1.6 Functional Entity: A Functional Entity (FE) comprises a specific set of functions at a given location. Functional Entities are logical concepts. Group
16、ing of Functional Entities are used to describe practical physical realizations. 3.1.7 Home Subscriber Server (HSS): The HSS stores all the static and dynamic information for a subscriber. It keeps a master list of features and services associated with a user, and also the location and means of acce
17、ss to the user. It provides user profile information, either directly or via servers. 3.1.8 Interconnection Border Gateway Function (I-BGF): The I-BGF is a packet gateway used to interconnect a service providers core network with another service providers core network supporting the packet-based ser
18、vices. There may be one or multiple I-BGF in a core network. The functions of the I-BGF may be the same as that of the A-BGF. As one key injection node for support of dynamic QoS control, NAPT/FW control and NAT traversal, the I-BGF performs the above functions on an IP flow under the control of the
19、 PDF. In addition, the I-BGF may support the following: Media conversion (e.g., G.711 and AMR, T.38, EVRC, and G.711); Inter-domain IPv4/IPv6 conversion; Media encryption; and Fax/modem processing. ATIS-1000018 4 3.1.9 Interconnection Border Control Function (IBCF): The IBCF controls the I-BGF to in
20、terwork with other packet-based networks. The IBCF may support the following functions (not limited to): Inter-domain network topology hiding; Inter-domain protocol normalization and/or repair; Inter-domain protocol interworking; and Interaction with PDF for resource reservation, resource allocation
21、, and/or other resource related information (e.g., the available resource parameters if the required resources are not available, QoS label, etc.). 3.1.10 Media: Media consist of one or more of audio, video, or data. 3.1.11 Media Gateway Control Function (MGCF): The MGCF controls the parts of the ca
22、ll state that pertain to connection control for media channels in a T-MGF. It selects the CSCF depending on the routing number for incoming calls from legacy networks. It performs protocol conversion between ISUP and the NGN call control protocols (e.g., SIP) and maintains call states. 3.1.12 Media
23、Resource Broker (MRB): The MRB: Assigns specific MS resources to incoming calls at the request of service applications (i.e., an AS), which happens in real time as calls come into the network; Acquires knowledge of media server resources utilization and reservation requests that it can use to help d
24、ecide which MS resources to assign to resource requests from applications; and Employs methods/algorithms to determine MS resource assignment. 3.1.13 Multimedia Resource Function Controller (MRFC): The MRFC controls the media stream resources in the MRFP under direction from an S-CSCF or Application
25、 Server. It interprets information coming from an AS or S-CSCF (e.g., session identifier) and controls MRFP accordingly 3.1.14 Multimedia Resource Function Processor (MRFP): The MRFP provides media resources under the direction of MRFC. It may generate media streams (e.g., multimedia announcements),
26、 mix incoming media streams for multiple parties, or process media streams (e.g., audio transcoding, media analysis). 3.1.15 Media stream: A media stream can be of audio, video, or data type, or a combination of any of them. Media stream data conveys user or application data (payload), but no contro
27、l data. 3.1.16 Policy Decision Function (PDF): The PDF provides management of network QoS resources within its own network necessary to support services to network users. It communicates with the A-BGF to provide authorization of resource allocations. The PDF makes policy decisions with regard to us
28、e of network QoS resources within its own network, including consideration of Service Level Agreements (SLAs). QoS policy information for network resource utilization may be forwarded to and cached by the PDF. PDF manages resources of the A-BGF that handle traffic between low-speed networks and the
29、high-speed backbone core network. Additionally, the PDF makes policy decisions based on information obtained from P-CSCF. 3.1.17 Reference point: A reference point is a conceptual point at the conjunction of two non-overlapping functional entities that can be used to identify the type of information
30、 passing between these functional entities. A reference point may or may not correspond to one or more physical interfaces between pieces of equipment. ATIS-1000018 5 3.1.18 Service Broker: The Service Broker provides service distribution, coordination, and control functions between application serv
31、ers, media servers, and services that may exist on alternate technologies. It allows control of applications in conjunction with their service data and media resources to create other value added services. 3.1.19 Signaling Gateway Function (SGF): The SGF acts as a gateway between the IP call/session
32、 control signaling and the SS7-based PSTN signaling. It can also be used as a signaling gateway between different packet-based carrier domains. It may provide signaling translation, for example between SIP and SS7 or simply signaling transport conversion - e.g., SS7 over IP to SS7 over TDM. 3.1.20 S
33、ubscription Locator Function (SLF): The SLF is queried by the I-CSCF during the Registration and Session Setup to get the name of the HSS containing the required subscriber specific data. Furthermore, the SLF is also queried by the S-CSCF during the Registration. 3.1.21 Stream: A stream is a flow of
34、 real-time information of a specific media type (e.g., audio) and format (e.g., G.722) from a single source to one or more destinations. 3.1.22 Topology: Topology is information that shows the structure of a network. It contains the network address and the routing information. 3.1.23 Trunk Media Gat
35、eway Function (T-MGF): A T-MGF terminates bearer channels from a switched circuit network and media streams from a packet network (e.g., RTP streams in an IP network). It establishes and releases connections between these channels under control of the MGCF in support of calls between PSTN and IP net
36、work. The T-MGF supports media conversion and processing (e.g., codec, echo canceller, conference bridge). 3.2 Acronyms they include functions related to support for QoS and traffic control. The Edge functions are also used between core transport networks. 5.2.1.3 Core Transport Functions The Core T
37、ransport functions are responsible for ensuring information transport throughout the core network. They provide the means to differentiate the quality of transport in the core network. These functions provide QoS mechanisms dealing directly with user traffic, including buffer management, queuing and
38、 scheduling, packet filtering, traffic classification, marking, policing, shaping, gate control, and firewall capability. 5.2.1.4 Gateway Functions The Gateway functions provide capabilities to interwork with end-user functions and/or other networks, including other types of NGN and many existing ne
39、tworks, such as the PSTN/ISDN, and the Internet. ATIS-1000018 11 Gateway functions can be controlled either directly from the Service Control functions or through the Transport control functions. 5.2.1.5 Media Handling Functions The Media Handling functions provide media resource processing for serv
40、ice provisioning, such as generation of tone signals and transcoding. These functions are specific to the transport stratum. 5.2.2 Transport Control Functions The Transport Control functions include Resource and Admission Control Functions and Network Attachment Control Functions, which are for furt
41、her study. 5.2.3 Transport User Profile Functions The Transport User Profile functions take the form of a functional database representing the combination of a users information and other control data into a single “user profile” function in the transport stratum. This functional database may be spe
42、cified and implemented as a set of cooperating databases. 5.3 Network Management Functions Support for management is fundamental to the operation of the NGN. These functions provide the ability to manage the NGN in order to provide NGN services with the expected quality, security, and reliability. M
43、anagement functions apply to the NGN service and transport strata. For each of these strata, they cover the following areas: Fault management Configuration management Accounting management Performance management Security management The accounting management functions also include charging and billin
44、g functions. These interact with each other in the NGN to collect accounting information, in order to provide the NGN service provider with appropriate resource utilization data, enabling the service provider to properly bill the users of the system. ATIS-1000018 5.4 End User Functions No assumption
45、s are made about the diverse end-user interfaces and end-user networks that may be connected to the NGN access network. Different categories of end-user equipment are supported in the NGN, from single-line legacy telephones to complex corporate networks. End-user equipment may be either mobile or fi
46、xed. 6 FUNCTIONAL ARCHITECTURE AND INTERFACES This section describes the details of the functional architecture for the NGN, including the definitions of the FEs. This architecture supports SIP-based sessions and is independent of services. It is designed to support multiple implementation technolog
47、ies and can be instantiated in customized architectures that can respond to specific contexts in terms of the services offered and the technologies used. The NGN functional architecture shown in Figure 2 is based on the NGN architecture overview provided in section 5. In particular, the functional g
48、roups identified in Figure 1 are used to structure the general layout of Figure 2. The mappings between the FEs in Figure 2 and functional groupings in Figure 1 are detailed in this section. OtherIPNetworksASP-MwMwMxMrMiDxSh/SiRf/RoPSTN/ISDNUEMgGmISCIcIbMjCxDhRf/RoCxIwIdPSTNMGCFI-CSCFHSSS-CSCFMRFCSL
49、FCharging FunctionSGFIWFI-BGFASIBCFMRFP T-MGFP-CSCFMSA-BGFPSTNGWBGCFSIPH.248DIAMETEROtherMRB*PDFGqGqSB*S/I-CSCF* Specialized AS* Also known as a SCIMNote: PDF interfaces between two interconnecting networks are not shown.MpGoMnRf/RoRf/RoRf/RoMxDxInter-connectSBCAccessSBCA2A13rdPartyApplicationsANIMgFigure 2 - ATIS NGN Functional Architecture 12 ATIS-1000018 13 Some of the FEs in this functional architecture may include functionality that spans both the service stratum and the transport
