The attention problem of SoftSwitch application network

SoftSwitch Network is more commonly used, so I studied the application of SoftSwitch network must pay attention to the problem, here to share with you, hope for everyone useful. Human communication consists of three main contents: Voice, data, video and audio combination of multimedia. All these three types of communication services have been carried out and unblocked by different communication networks respectively. The telephone network carries and dredge the voice service, the data network carries and dredge the data service, the multimedia network carries and dredge the multimedia service.





with the further deepening of social informatization degree, communication has become an indispensable tool for people's lives and work, people's communication requirements are no longer just basic voice communications business and simple WWW browsing and sending and receiving e-mail, people need to be able to readily, anywhere, flexibility to obtain the required information. Therefore, telecom operators are required to be flexible to provide users with a wealth of telecommunications services, but based on the different communication network to provide different business operation mode is difficult to meet the user "flexible access to the required information" needs, only to build a "full business network-that is, can host and dredge voice, data, multimedia business Network" To meet the growing demand for communications services.





Telephone Network has the longest history, its core is the telephone switchboard, the telephone exchange experienced the magnet type, the common battery type, the step system, the aspect system, the program control System 5 Development stages, its difference is the switch realization way has changed. The emergence of the process Control telephone switch is a historical change, it uses the advanced architecture, its function can be divided into call service access, routing (Exchange) and call service Control 3 parts, in which the Exchange and call service control functions are mainly through the program software to achieve. But its use of resource exclusive circuit exchange, as well as the reciprocal two-way 64kbit/s fixed bandwidth channel for communication is not suitable for carrying data services with large bursts of data and large difference in data flow from top to bottom.





A wide range of data networks, according to their use of different WAN protocols, can be divided into DDN, X.25, Frame Relay and IP network, because the IP network has a simple protocol, low-cost terminal equipment, as well as the implementation of the WWW service based on IP protocol, the Internet based on IP protocol has exploded development, Once became a synonym for data networks. The IP network requires the user terminal to encapsulate the user data information in the IP packet, the IP network's core equipment--the router is only completes the "best" IP packet forwarding simple work, it uses the resource sharing packet Exchange way, according to the business quantity needs to occupy the upper and lower row transmission channel dynamically, Therefore, the IP network is actually only a data transmission network, it does not provide any high-level business control functions, if the IP network to open Voice services, you must add additional control equipment for the telephone service. It is worth mentioning that IP packets can carry any user data information, so that the voice, data, multimedia flow and other information in a bearer network to create conditions. It can be seen that both the telephone network and the data network have some congenital defects, can not be easily transformed into a "full business network", therefore, in order to be able to provide voice, data and multimedia services on the same network, that is, the integration of communication services, the formation of soft switching (softswitch) technology.





Soft Switch Technology Introduction





1. The overall structure of SoftSwitch network





Soft Switching technology adopts the advanced architecture of telephone switch, and uses IP packet in IP network to carry the information of voice, data and multimedia stream. A program-controlled switch can be divided into 3 functional modules for business access, routing (switching) and business control, and each function module is connected to a whole through the internal switching network of the switch. SoftSwitch technology is to separate the above 3 functional modules, respectively by different physical entities to achieve, at the same time carried out a certain function expansion, and through a unified IP network of physical entities connected to form a SoftSwitch network.




The service Access function module of
telephone switch corresponds to the edge access layer of SoftSwitch network, the routing (switching) function module corresponds to the control layer of SoftSwitch network, the Service control module corresponds to the business application layer of SoftSwitch network, and the IP network forms the core Transport layer of SoftSwitch network.





2. Edge Access Layer





SoftSwitch technology makes the business access module of the telephone switch become a physical entity, called the Media Gateway (MG), the MG function is to use various means to connect all kinds of users and services to SoftSwitch network, and MG completes the transformation of data format and protocol. All media streams that are connected are converted to packets using IP protocols for transmission in softswitch networks. Depending on the user and business of MG access, MG can be subdivided into the following categories.





Relay Media Gateway (TG): Used to complete a relay connection to a PSTN/PLMN telephone switch, which converts a voice signal from a 64kbit/s in the PCM relay of a telephone switch to an IP packet. Signaling Gateway (SG): Used to complete a signalling connection with the PSTN/PLMN telephone switch, which converts the seventh signaling information based on the TDM circuit to the IP packet used by the telephony switch. TG and SG have jointly completed the connection between SoftSwitch Network and PSTN/PLMN telephone network with TDMA circuit Exchange, and the ordinary telephone users and their services in PSTN/PLMN network are connected to the SoftSwitch network. Access Gateway (AG): Provide analog user line interface for direct access to the ordinary telephone users to the SoftSwitch network, can provide users with all the services PSTN, such as telephone services, dial-up Internet services, it directly to the user data and user line signaling package in the IP packet.





Integrated Access Equipment (Iad,integratedaccessdevice): A class of IAD also provides analog user line and Ethernet interface, respectively for the access of ordinary telephones and computer equipment access, suitable for the use of telephones, respectively, using telephone service, The user who uses the computer to use the data business; another type of IAD provides only Ethernet interfaces for access to computer equipment, which is suitable for users who use the computer for both the telephone service and the data business, to install a dedicated "soft phone software" in a user's computer device. Multimedia Service Gateway (Msag,mediaserversaccessgateway): Used to complete a variety of multimedia data sources of information, video and audio mixed multimedia streaming adapter for IP packets. H.323 Gateway: An IP telephony network gateway used to connect the H.323 protocol. Wireless Access Media Gateway (Wag,wirelessaccessgateway): Used to connect a wireless access user to a soft switching network.





It can be seen that the AG, TG and SG complete the function of the service Access function module of the telephone switch, realize the access of the Voice service of the ordinary PSTN/PLMN telephone user, and adapt the voice information to the IP packet which is suitable for transmission in SoftSwitch network. At the same time, SoftSwitch technology also expands the service access function, which is embodied in iad, msag, H.323GW, WAG and other types of media gateways. Through all kinds of MG, SoftSwitch network realizes the integrated access to the voice, data and multimedia services of PSTN/PLMN users, H.323IP telephone network users, ordinary landline users and wireless access users.





3. Control Layer





SoftSwitch technology to separate the switching module of the telephone switch into a physical entity, called the Soft Switch (SS), the main function of SS is to complete the control of all media gateways in the edge access layer and the communication between media gateways, the specific functions are as follows.





(1) determines the user's business usage rights based on the user attributes registered in the business application tier related server to determine whether to accept the user-initiated business request.





(2) controls the resources of various media gateways in the edge access layer, controls the use of each media gateway resource, and grasps the resource occupancy of each media gateway to determine whether there is sufficient network communication resources to meet the business requirements of the users.





(3) completes the call routing function, according to the user initiates the service request the related information, determines which media gateway should establish the communication connection relation, and informs these media gateways to establish the communication connection relations and carries on the communication, as well as in the communication process uses the information compression coding way, Whether to enable features such as echo suppression.





(4) monitors and controls the state of communication connections between media gateways, indicating that the corresponding media gateways are disconnected from each other after the user's service is completed.





(5) billing. Because the soft switch is only to control the continuity of the business, and the data flow between users is not through the soft switch, so the soft switch can only be realized on the basis of continuous time billing, and can not be realized by the amount of information billing. If the soft switch has the function of charging by information, it requires the media gateway to have the function of counting the amount of information per user for each use of the business, and can transmit the statistic results to the soft switch.





(6) With the H.323 Network (GK) interactive Routing and other information to achieve the SoftSwitch network and H.323IP telephone network exchange.





4. Business Application Layer





SoftSwitch Technology makes the business control module of telephone switch become a physical entity, called Application Server (AS), as the main function is to complete the implementation of the business, the specific functions are as follows.





(1) stores the user's contract information, determines the user's usage rights to the business, and generally uses the dedicated user database server +AAA server or the Intelligent network SCP to realize.





(2) uses the dedicated application server and the Intelligent Network SCP (requires the soft switch to have the SSP function) to realize the basic telephone service and its supplementary service function as defined in the general Technical Specification Book of the Ministry of PTT telephone exchange ydn065-1997, and the telephone card that the intelligent network can provide, is called the pay and other intelligent network business.





(3) using a dedicated single application server or multiple application servers to achieve the integration of voice, data and multimedia business, flexible to provide users with a variety of value-added services and characteristics of the business.





(4) SoftSwitch network control layer between the soft switch is not graded, when each additional soft switch in the network, all other soft switches must increase the corresponding Bureau data, which for network operations, will be extremely troublesome, The solution is to set up a policy server in the business application tier to provide routing information for the soft switch. Of course, the setting scheme of the policy server will directly affect the security and reliability of SoftSwitch network.





5. Core Transport Layer





core Transport layer is actually a network of SoftSwitch network, its function and function is to the edge access layer in a variety of media gateways, the control layer in the soft switch, the business application layer of various server platforms and other soft switching network elements connected.





because the IP network can host voice, data, video and other media information at the same time, it has the advantage of simple protocol, good support to the protocol and low price, so the SoftSwitch network chooses the IP network as the host network. Each network element in SoftSwitch network encapsulates all kinds of control information and business data information in IP packet, and communicates through the IP network of core transport layer. 3lian.com





6. Protocol and standard
in SoftSwitch network



The standard protocols defined by SoftSwitch technology are used to communicate between the same layer network elements and different layers in
softswitch network. The international organizations engaged in the development of SoftSwitch-related standards are mainly IETF and ITU-T. They have made contributions to softswitch network agreements from the standpoint of the computer and telecommunications sectors