Softswitch architecture and business support environment (1)

As a hot topic in recent years, the next generation network has received wide attention from various aspects. However, people in different fields have different understandings of the Next Generation Network. There is no standard definition of what the next generation network is. From the Internet field, the next generation network refers to the next generation Internet NGI); for mobile networks, the next generation network refers to 3G and the next 3G networks; in terms of control, the next generation network refers to Softswitch; in terms of transmission network, the next generation network refers to the next generation optical network. Obviously, the Next Generation Network (NGN) in the broad sense embraces all new generation network technologies.

Softswitch architecture

Coexistence of heterogeneous networks is the current status of the network, while convergence of multiple heterogeneous networks is the trend of the times. With the rapid development of the IP network, Softswitch will take the IP network as the backbone and provide services flexibly in a unified manner based on the convergence of various networks. Softswitch is the control core of the Softswitch system. It is independent of the underlying bearer protocol, it mainly implements call control, Media Gateway access control, resource allocation, protocol processing, routing, authentication, billing, and other main functions, and can provide users with services available for the existing network, and provides access interfaces for the underlying network capabilities to the business support environment. The application server is the subject of the business support environment in the softswitch system and the core of business provision, development and management. Softswitch Network System 1.

Figure 1 architecture of the Next Generation Network

The softswitch network can be divided into service plane, control plane, transmission plane and access plane.

The access plane provides various methods and means for connecting networks and devices to the core backbone network, including signaling gateways, media gateways, access gateways, and other access devices.

The transport plane is responsible for providing various signaling and media stream transmission channels. The core transmission network of the network will be an IP group network.

The control plane provides Call Control, Connection Control, protocol processing, and other capabilities, and provides an open interface for the business plane to access various underlying network resources. The main component of the plane is the softswitch device.

The application plane uses various underlying network resources to provide users with a wide range of network services. It mainly includes Application Server, Policy Server, and AAA Server. The most important functional entity is the application server, which is the business execution environment in the softswitch network system.

At present, the interfaces between entities in the softswitch network system have not yet been finalized, but some consensus has been reached, and the Ministry of Information Industry has also prepared draft standards. In terms of signaling, SS7 signals are converted into SIGTRAN signals developed by IETF through the signaling gateway as interfaces with Softswitch devices, softswitch devices communicate with each other through Megaco/H.248 control media gateways and access gateways jointly developed by ITU-T and IETF through SIP-T protocols or BICC protocols developed by ITU-T. Interfaces between Softswitch devices and application servers are currently favored by open API application programming interfaces, for example, Parlay API standards developed by Parlay. In terms of media, the media gateway packs traditional fixed and mobile network voice packets into groups and transmits them on the Core IP network in the form of RTP streams.

It can be seen that Softswitch uses a layered and open architecture to separate functional modules of traditional switches into independent network entities, and open protocols or APIs are used between entities, this breaks through the closed structure of traditional telecommunication networks and achieves the convergence of multiple heterogeneous networks. The next generation network system achieves a relatively independent business system by separating services from call control, call control and bearer, so that upper-layer services are independent of the underlying heterogeneous networks, the service is provided flexibly and effectively to meet diverse and evolving business needs. It can be said that Softswitch fully embodies the business-driven ideas and concepts, achieves a good convergence of multiple networks, and provides an open and flexible business provision system.

Business Support Environment

The business support environment mainly includes the application server, Business Management Server, and business generation environment. They work together to quickly complete the tasks that provide users with diverse and flexible value-added services based on the next generation network. The application server is the subject of the business support environment. The Business Management Server and business generation environment can be used as part of the application server.

Figure 2 SIP Application Server