IPCC Packet Communication Reference Structure 2.0
Http://www.chinatelecom.com.cn November 17, 2003 China Telecom Group Beijing Research Institute
Summary: In April 2003 IPCC released a Group 2.0 version of the Group 2001, which is an upgrade of version 1.0 in 2001, which is to make a unified term for next-generation group voice network. In this paper, the author will analyze the main content of the packet communication reference structure and combine the current domestic NGN standard and the status quo of NGN equipment at home and abroad. Keywords: Grouping Communication Structure NGN In April 2003 IPCC (International Packet Communication Alliance) released a group communication reference structure version 2.0, which is a unified term for next-generation group voice networks. As early as June 2001, IPCC issued a softswitch-based group communication reference structure version 1.0. With the development of NGN (next-generation network) technology in the past two years, it has been clarified in version 2.0 in the Group 2.0 version of the group communication reference structure. This version is for increasing the interoperability between the various manufacturers and further clearly defines the network functional elements constituting the "Packet Communication Structure" and clarifies the differences and confusion that exists in the manufacturer of grouping voice products and services. It can be said that the group communication reference structure version 2.0 is a bright lamp at the current NGN industry, which illuminates the unified development direction of the NGN device and the network based on soft exchange. In this paper, we will analyze some analyzes for the main content of the group communication reference structure version 2.0 and in conjunction with the current domestic NGN standard and the status quo of NGN equipment at home and abroad. 1. Defining the packet communication structure of the packet communication structure is a combination of software and hardware platforms, which is used to implement communication services in packet networks. The packet communication structure includes both network intelligence of coordinated call control and signaling, and also includes characteristics across one or more networks to initiate multimedia calls. The main function of the packet communication structure is to perform real-time multimedia communication. The key requirement for real-time communication is call control, which completes the establishment and demolition of the call. Call control and service logic are corresponding to the feature of processing calls and providing telephone features. The idea of packet communication structures for IPCC is exact consistent with the basic idea and philosophy of softswitch-based next-generation networks advocated. 2. Functional Entities of Grouping Communication Structure 2.1 Functional Plane Packet Communication Structure of Packet Communication Structure Contains Three Functions Plane: • Access Plane: Provides adaptation between different media transmission methods, the plane processing TDM to packet conversion and letter Transmission; Transmission plane: Provides transmission interoperability between other planes, the flat processing simple packet transmission; • Application plane: Provide the information of the signaling and media required by the user service. Operation. IPCC function plane definitions are slightly different from the current domestic softswitch standard, and the domestic standard has no transfer plane and the definition of the control plane is the same. The IPCC contains the contents of the control plane in the access plane, and uses a transmission plane that provides interoperability between the access plane and the application plane. This plane division method seems to be more blurred, but in combination with the definition of the following functional hierarchy, divide the vertical and horizontal axial direction (placed the media gateway function in the media layer of the access plane, the media gateway controller is placed in access Planned business layer), which makes the functional entity of the packet communication structure more clear. 2.2 The functional hierarchical IPCC of the group communication structure is another difference between the domestic softswitch standards to define the functional plane, and the functional level of the packet communication structure is defined. IPCC defines four levels to describe the working principle of end-to-end voice packet network. These four levels are: • Signaling layer: Provide two main functions. The first is the signaling of the traditional network to the packet voice network, the second is the signaling in the routing group voice network. An example of an adapter is a H.323-SIP signaling gateway, and the other is the SS7 signaling gateway. The example of route is the SIP proxy and routing logic in the media gateway controller. · Business Layer: Provide control, logic, and execution of one or more traffic or applications in group voice networks. By communication with signaling and media layers, the traffic layer device controls the call flow based on the business execution logic. The service of the business layer includes a media gateway controller (soft exchange) and application server. · Media layer: Provide media processing services to the business layer. Media layer devices include media gateways and media servers.
· Management: It is a place for user service providing, operation and maintenance, alarms, and error management, accounting, and other network management tasks. The management is communicated with other layers through standard protocols such as SNMP, LDAP, DIAMETER. 2.3 Functional entity of the packet communication structure The functional entity of the communication structure includes: Media Gateway Controller Function (MGC-F), Signaling Conversion Function (SC-F), Media Gateway Function (MG-F), Application Server Function (AS -F), media server function (MS-F), billing function (AF), hereby elaborated. 2.3.1 Media Gateway Controller Function (MGC-F) Media Gateway Controller (MGC) is used to control the media gateway and signaling gateway. The media gateway handles call establishment and demolition, event detection, and processing, gateway start, and shutdown by using the database of record relay groups and relay circuits. The media gateway controller has a lot of names. It is generally referred to as soft exchange, and it is also called a call agent or call controller abroad. The basic feature of MGC-F is: • Maintaining a call status of each call on the media gateway; • Maintaining the transmission status of the transfer interface on the MG-F. In addition, MGC-F can also have a small built-in SC-F, but this is currently uncomfortable on domestic electric telecommunications-class softswitch devices. 2.3.2 Signaling Conversion Function (SC-F) Signaling Conversion Function (SC-F) Routing and Operation Signaling. This signaling operation can be both very simple (for example, reheedui-URI in the SIP agent), or a very complex (SS7 signaling gateway CRC from a transmission medium and message format to another transmission medium and Message format). SC-F features: • Use the SigTRAN package and transmit the PSTN signaling protocol to MGC-F or another SC-F; · A SC-F can serve multiple customers (MGC-F, SC-F or AS- F); • In grouping voice networks, the SIP proxy provides a route translation of the SIP message by operating the target address of the SIP message. Here, we need to point out that we will generalize the SIP network as a unique NGN network, but the SIP agent is described as SC-F in the Packet Communication Reference Structure 2.0, which fully embodies the structure. The idea of the network and group communication structure (NGN) fully integrated. 2.3.3 Media Gateway Function (MG-F) Media Gateway is an interface between packet networks and access endpoints or network relays. It converts media from one transmission mode to another, usually between circuit networks and packet networks or between different packet networks (such as ATM, IP). The features of MG-F include: • Using equipment control protocols such as H.248 or MGCP to maintain the master / royalty between MGC-F; · Execute media processing functions, such as media decoding, echo suppression, media packetization, jitter buffer Manage, package loss compensation, etc. Detection, voice activity detection, waiting. 2.3.4 Application Server Function (AS-F) Application Server Function (AS-F) is an application's executive entity. Its main responsibility provides business logic and execution to one or more applications or services.
The features of the application server include: • Equation of the application signaling (such as voicemail or conference bridge); · During the execution logic of the featured call (if you find me / follow me or the prepaid card); · Provide the web interface to fusion real-time multimedia And web applications; · There is a business-generated API (such as SIP Servlet, Parlay, Jain); · You can have a policy, billing, session log background interface; · Can activate another for additional business or to construct complex component applications A as-f; request MGC-F service to control external resources; • Request MS-F service to execute media operations; • Applications including SIP, LDAP, HTTP, CPL, and XML. Usually the combination of AS-F and MGC-F provides enhanced call control services, such as network notifications, tripartite calls, call waiting, and the like. Vendors usually do not use protocol to connect AS-F and MGC-F, but use APIs between AS-F and MGC-F. 2.3.5 Media Server Function (MS-F) Media Server The purpose of providing media processing capabilities to support applications such as messages, audio conferences, music retention. The features of MS-F include: Support multiple coding and decoding; support multiple AS-F or MGC-F control; · Support multiple concurrent capabilities: digital detection, audio and notification stream, encoded audio generation, multimedia Flow record, speech recognition, text to voice conversion, media mixing; · Support standard scripting language, such as VoiceXML or MSCML; • Control requests for tight coupling (resource control, such as MGCP) or loose coupling (server request, such as SIP) Execute it under the control of AS-F or MSC-F. 2.3.6 Billing function (A-F) A-F collects all billing information for accounting purposes. The features of A-F include: • Detailed records for each session for billing purposes; • Provide session management and mobility management; • In order to implement AAA (authentication, authorization, accounting), A-f is usually combined with SC-F. In conjunction with A-F and SC-F, it is very different from the current NGN equipment at home and abroad, which is generally among the soft exchange devices (MGC-F). The IPCC reference structure above describes the various functional entities described above by two dimensions. The Y-axis is divided according to the functional hierarchy, and the X-axis is divided into the access plane or the application plane according to the function entity. The reason why the access network function entity is distinguished from the application network function entity because the main purpose of the group communication structure is independent of the access technology. From the above figure, you can know that MG-F, MGC-f is a member of the access plane, MS-F, AS-F is a member of the application plane, and SC-F is both an access plane and belonging to an application plane. 3. The correlation protocol packet voice technology of the group communication structure contains a variety of protocols. These protocols are divided into four categories: · Call control protocol: H.323, SIP · Media Gateway Control Protocol: MGCP, H.248 · Transfer Protocol: RTP · Signaling Gateway Protocol: SigTRAN Figure 2 illustrates the above protocols and them How to interconnect the various telecommunication NGN devices in the operator network. From this figure we can see that IPCC's dispute between SIP-T and BICC is significantly inclined to SIP-T. 4. Network Examples This section will illustrate the packet voice network configuration instance in three practical applications. Each network instance illustrates that different functional entities will appear in a physical device and form a packet speech network in a logical interconnection.
