In-depth analysis of basic concepts of vswitch Technology

The soft switch technology is still quite common, so I have studied the basic concepts of the soft switch technology. Here I will share it with you and hope it will be useful to you. At present, people are familiar with the separation of voice, data, and video networks will gradually evolve into an open next-generation communication network (NGN) that integrates multiple services, grouped IP addresses ).

Over the past year, people have been paying attention to and discussing NGN in line with this market trend. Fortunately, although there are some differences in the expression of NGN, the general principles of NGN are as follows: NGN will be based on the grouped data network and Unified IP protocol, even those who have conservative opinions on IP grouping technology agree that the integrated data network technology will become the core network technology of telecom operators in the next few years, no one raised any objection to IP technology as the basic backbone service platform of the telecom operator NGN. NGN will mean that the transmission technologies of various services and applications are completely forward and integrated into grouping and broadband IP addresses. Smart light, DWDM, and high-speed routing and group switching technologies will be fully utilized.

NGN will provide an integrated and open network architecture system. Its development goal is to integrate various application networks with a unified network technology to achieve end-to-end multimedia service convergence. The NGN network will unify various service networks-wireless and wired networks, fixed networks and mobile networks, voice networks and data networks-on a common Transmission Basis and network application platform.

As a technical representative based on the commercial hardware platform and adopting open, standard, multi-protocol, and operational management, the soft switch technology will become one of the important and critical systems and equipment technologies in NGN. However, it must be seen that, due to the rare networking and practice of vswitches with a certain scale in China, the Discussion and Practice of vswitches only focus on the concept of local and individual technologies. Over the past one year, people have been familiar with soft switches and have learned more about them, starting to discover that building NGN with a single soft switch technology will face a series of challenges and some fundamental conflicts. I believe that the core of some of the key issues may not be technology, but the concepts, perspectives, and ways of thinking that we are familiar. Therefore, the author believes that it is necessary to review the concept and features of the Soft Switch Technology and Its Role in NGN.

Basic concepts of vswitches

Although soft switches are currently a hot topic in the discussion of NGN, their concepts are still somewhat plausible. So is it a device concept? A System Concept? A technical architecture? What is the relationship between a soft switch and an IP address phone and an NGN ﹖

1. Origin of Softswitch

The term "Soft Switch" can be said to have been translated from foreign countries. Its concept is basically formed with the development of the functional hierarchy of the IP telephone technology system and the concept of control separation. As we all know, in the traditional PSTN switching network, business control, call control, and transmission load are all concentrated in switches, and various services of the PSTN must be implemented through the TDM switch. To meet users' demand for new services, a public service generation platform (Intelligent Network) appears in the PSTN network. The PSTN intelligent network proposed for the first time and implemented the separation of some all-network service generation and call control. Therefore, it improved the development of all-network services of the PSTN and improved the capability of centralized network service provision, this shortens the cycle for providing new services across the network. The IP telephone technology system not only further strengthens the idea of separation of service generation and call control, but also looks forward to the separation of Call Control and media transmission bearer. The goal of this separation is to allow the control and generation of IP phone services to be truly ***** used in media transmission network facilities, this allows for more flexible and effective integration of IP phones and their related services and multimedia applications. More importantly, this separation also facilitates telecom operators to implement centralized operations, governance, maintenance and preparation of OAMP on the group network. Telecom operators and users can customize configurations and manage their own business characteristics through IP connections in the local system, without worrying about the types and configurations of user terminals, in this way, the provision of services and applications is highly possible, flexible, and operational governance.

2. Definition of vswitches

So what is a soft switch? According to the definition of isc in the international Softswitch Forum, Softswitch is a device and system that uses program-controlled software to provide call control functions based on the sub-network. According to this definition, Softswitch is a typical technical practice designed for the speech purpose of the sub-networking. This definition also indicates that Softswitch borrowed the concept of "hard" switch in the PSTN network in the traditional telecom field, the difference is that it is based on the meaning of separation of sub-networking and call control and media transmission bearer. Softswitch is an important component of NGN, but it focuses more on the devices and systems of call control functions. It cannot constitute an extraordinary overall networking technical mechanism and network architecture. But why is this simple concept confusing? One of the reasons may be that many people in China translate Softswitch into "Softswitch ". The term "Softswitch" is not clear enough to give it a logical illusion. It is literally difficult for people to understand whether it is a device system concept or a system concept. China's telecom industry has always translated switch as switch, while switching as "switch ". So why are we making an exception here? What's even more troublesome is that it is difficult for Chinese to distinguish between "softswitching" and "softswitch. Therefore, I believe that we should translate Softswitch into soft switches more accurately for the rigor of academic research. In the formal written language, "Softswitch" should be avoided as a short name for soft switches.

3. Significance of the technical foundation and concepts of vswitches

The technical basis of vswitches is MGCP/H. 248 media control protocol. Media control protocol, also known as Device Control Protocol, is a so-called master-slave relationship control protocol. Generally, a simple device or device that is not in the Smart State is not included in the prosecution. All status events and changes must be reported to the master device. Therefore, media control protocols should not be considered call signaling and can only be used to control endpoints, including user terminals and relay endpoints. MGCP/H cannot be used for inter-board call signaling protocols of vswitches. 248, but must use the existing multimedia international standard, that is, the itu h. 323 protocol and/or ietf sip protocol.

Vswitches use media control protocol technology to separate call control from media transmission. Therefore, some foreign scholars refer to soft switches as call proxies (CA) or media gateway controllers (MGC ). The concept of a soft switch not only enables the voice service function of NGN and the switch function of the traditional PSTN network to be completely transparent, but also fundamentally ensures that the IP telephone technology can completely replace the PSTN network.

Technical Features of vswitches

People's opinions on the technical features of vswitches are basically consistent. According to the concept of vswitches, the technical features of vswitches are based on MGCP/H. 248 media control protocol, realizing the separation of Call Control and media transmission. Although the goal of NGN is to gradually integrate the voice, data, and video services into a collection of multiple services over the IP network, however, it still faces the fundamental challenge of finding a mature IP phone technology that can handle large-scale operations. Voice is the most popular, basic, and important service for carriers. It covers the widest range of the market and has a greater impact on business revenue than other businesses. After nearly a hundred years of development, the traditional PSTN technology and TDM network provide mature business models and quality standards for the operator's voice business. A Data IP network was originally designed for data services, while a speech is a time-sensitive service, the IP telephone technology that provides large-scale voice services in data IP networks is the primary challenge for any operator in the transition to NGN.

Vswitches are designed to implement the functionality of the PSTN vswitch on the IP network. Vswitches of the traditional PSTN network are vertical, closed, and private system structures. Soft switches are standard-based and open system structures separated by call control and media. In addition, the "hard" switch of the soft switch and the PSTN has many common attributes. For example, they are system devices that are relatively centrally controlled and managed, and all user-oriented data and call status information are stored in the system. This makes the soft switch very important to telecom operators, because only in this way can we meet the telecom operation requirements to implement effective call service control and O & M management for IP-based network endpoint access and interconnection with PSTN.. Therefore, soft switches are an important implementation method of IP telephone technology in NGN.

It is worth mentioning that, in order to support access to smart endpoints, video endpoints, and multimedia endpoints, soft switches may also support H. 323 protocol and SIP protocol to control governance H. 323 and the user endpoint of the SIP. In this way, the soft switch technology itself cannot completely implement call control and media transmission separation for all endpoints under its control and governance. In addition, as mentioned above, the soft switch must also support H in the "inter-office. 323 and the SIP protocol come with H. The 323 network is interconnected with the SIP network and other soft switches. However, MGCP/H. 248 media control protocol technology has always been a basic feature of vswitches. If the system of a call control device does not support MGCP or H. 248 media control protocols generally cannot be called soft switches. Generally, H is supported in the industry. The call control device with the 323 protocol as the notable feature is called the Gatekeeper keeper, and the call control device with the SIP protocol as the notable feature is called the proxy service ProxyServer.

In addition, although the soft switch supports the access of smart endpoints, video endpoints, and multimedia endpoints, it does not mean that all voice, data, and video services must be centrally implemented on the softswitch machine. Theoretically, even the possibility of such a device is completely unnecessary, because such a system does not have any advantages but has a series of overall architecture defects. In fact, the core design of the soft switch is focused on the Call Control Function of various businesses and the management of the endpoint capability to a certain extent. For example, a soft switch does not directly provide any form of IP data service. A soft switch can support the video endpoint service, but the video conferencing control function is not provided directly by the soft switch, it is achieved by connecting to other application servers.

Through a unified and IP-based transmission infrastructure, call control devices (vswitches) can be primarily used ), build a system with other IP technology and data application technology to support multimedia and other smart services. We can call such a system a soft switch system. In a broad sense, a soft switch system is a collection of multiple logical functional entities for call, media, and business control. It provides Call Control, connection, and some other functions for telephone terminals, smart terminals, and multimedia terminal services. Such a soft switch system can be used to control, manage service access, and manage local devices at the edge of the PSTN network. In this way, a variety of call control-related businesses can be integrated into the system for governance and operation. However, such a soft switch system will still adopt multiple distributed subsystem models to flexibly provide intelligent and multimedia business applications including voice in the integrated system. Therefore, from the telephone service provided by the soft switch technology and its technical characteristics, soft switches are an important component of the NGN system, however, it does not provide any fundamental innovations in the entire network architecture.