Analysis of networking scheme for SoftSwitch technology

The concept of SoftSwitch has been put forward for the first time since 1997, and it has received wide attention and recognition from the industry soon. A few years, in many manufacturers and operators under the common impetus, softswitch gradually mature, more and more functions, performance gradually stable, standardization work is steadily advancing, soft switching technology is moving to the market.

So far, a number of telecom operators around the world have been actively conducting experiments and commercial deployments in soft switching. In North America, 67% of local operators already have softswitch deployments, and 43% of long-distance switching operators are also deploying soft switching systems. In Europe, operators have adopted a more cautious approach to the development and application of SoftSwitch, but with the gradual maturation of softswitch technology, European operators have also speeded up the implementation of SoftSwitch. In the Asia-Pacific region, Hong Kong, New Zealand, Australia, Japan, South Korea and other countries in the field of soft switching applications in the forefront. Since 2000, China's telecommunications industry has also given great attention to SoftSwitch Network technology, China Telecom, Netcom, China Unicom, China railcom, China Satcom and Chinese mobile have all started the application of soft switching and commercial deployment. ---(Learn computer)

Technical test and practical commercial proof of the SoftSwitch network of each operator the SoftSwitch system has been basically mature in function and performance, and the problems are mainly focused on the following aspects:

With the gradual replacement of PSTN network with SoftSwitch network, the system should adopt the mode of large-scale network.

How to avoid the high degree of autonomy of IP network users, and realize the manageability of telecom operators to the business.

Compared with the closed circuit switching network with special system, SoftSwitch networks based on IP network are vulnerable to foreign intrusion and face the challenge of security. How to solve network nodes, user information and business security.

How to provide end-to-end real-time business with QoS assurance.

For users in the corporate private network, how to achieve business NAT equipment and firewall through the enterprise.

In order to solve the above problems, and considering the IP network itself to completely solve the security and QoS problems still need time, in this paper, a new network element device is introduced on the basis of the existing SoftSwitch network, and a new networking scheme is proposed, which helps the SoftSwitch network to advance to the commercial target. In favor of the traditional operators in the recent soft switching network commercial deployment.

Introduction of networking Scheme

1. Network structure

The network structure is shown in the following illustration:

　　

In order to better solve the problem of SoftSwitch networking, this scheme introduces the centralized user database HLR and the centralized routing server RS, separates the user data and the routing data from each SoftSwitch device (ss), and concentrates it in the HLR and RS, while the SS only keeps the information related to Gateway resources. such as the E1 of the relay gateway resources, and so on.

In order to solve the problem of network, business Security and QoS, this solution introduces a special carrier network with certain security and QoS guarantee (SoftSwitch service) and Edge access control equipment (BAC) for SoftSwitch service in the transport layer. Soft switching devices, relay Media gateways (TG), Integrated Access Media Gateway (AG), signaling Gateway (SG), key customers using IAD, Media server (MS), BAC and other devices based on private network deployment, the private network can be a new private networks or using MPLSVPN technology such as virtual private network, The communication between SoftSwitch devices and the message isolation between softswitch devices and non softswitch devices can be realized by various means. For non-critical customers using IAD and sip soft, hard terminals and other equipment, due to the number of equipment, widely distributed, will be through a variety of access to quickly converge to the BAC equipment, through the BAC Equipment and the private network to achieve interoperability with other equipment, at this time BAC provides signaling and media agent function and security detection and isolation function.

For IAD and sip users who access SoftSwitch networks through the public Internet, when a user initiates a business request, the terminal will first go to the SoftSwitch network DNS for the domain name resolution of the SS, to be based on the user location or IP address section of the distribution of the IP address of the BAC, the terminal will call request to the BAC, BAC goes to inquire whether the user is in the list of users who have passed the security registration, and if the signaling agent is used between the user and the SoftSwitch (BAC is equivalent to the SoftSwitch in the user's view, which is equivalent to the user in the soft switch). BAC sends the call request to the appropriate SS for processing according to the preset principle.

For the TG and ag/partial iad devices deployed on the network when the user initiates a business request, the gateway device will send the call to the corresponding SS according to the preset SS IP address.

The main name of the SS will first go to HLR query the user's business-related information, to determine whether the user's business is entitled to meet the preset business trigger conditions, and then according to the query results to access RS to obtain this call routing information, the call will continue to the next hop SS or business platform. Called SS received the call request will go to the query HLR, get the current user specified terminal IP address, and then to the terminal.

2. Equipment description

About RS

In the initial stage of the network development, the SoftSwitch equipment is not graded between each other for the logical mesh network structure, any SoftSwitch device in the network has the whole network routing information, can directly locate another soft switch device. The same operator network internal Soft Exchange is not graded, when interoperability with other operators network will be set up network indirect port SS and network indirect gateway relay.

With the expansion of the network scale and the increase of the number of SoftSwitch devices, the location server device is introduced to realize the routing query between SoftSwitch. The routing server accepts the address request of the caller SS, sends the addressing request to the other routing server through the data query, obtains and returns the called SS addresses to the caller SS, does not make call control signal transmission.
The initial RS can be unrated, and the hierarchical structure can be used as the scale of the network expands. When the SS routing data changes, it is necessary to update the change to the Rs,rs dynamically and automatically update the routing data. In other RS jurisdictions, the change of SS routing data does not require routing data changes to the zone SS, but only the routing data in the routing server.

RS will store the called number map of the routing information, can be the next SS IP address, or the next hop RS IP address, or a broadband user account registered multiple terminals of the address information, string and vibration sequence.

About HLR

As we all know, the intelligent degree of mobile network is higher than PSTN network, in which HLR credit can not be neglected. For softswitch Such a new network should be used for reference to the success of other networks, the centralized user database is introduced into the network, and the user data is managed centrally, which can store the business attributes (such as business permission, business user attribute trigger condition, etc.) of the user in the area of the tube. Because of the existence of HLR, the called side can be triggered on the main side, so that the user data can be stored in one place, which solves the problem of the real-time synchronization of the user modified business data to the backup soft Exchange when the user database is separated by the soft exchange.

The HLR adopts the multi machine backup method to improve its reliability.

About BAC Equipment

The Edge Access Control (BAC) device of SoftSwitch service is introduced to solve the problem of network security, QoS and private network crossing. Main features include:

(1) Business through function

The equipment supports SoftSwitch users and SoftSwitch devices in the private network or when the two sides are in different private networks of user business through.

The device supports the user's registration process, does not change the user's registration process, and the user's authentication is performed by the soft exchange.

The device supports the business of all softswitch services, does not change business processes, and does not introduce business security risks.

(2) Security function

The equipment can screen the soft switch device, the relay Media gateway, the integrated Access Media gateway, the media server and other equipment's address, and protect the important network element equipment.

The device has the function of a packet-filtering firewall to isolate network-level attacks.

The device can block access to softswitch devices without the permitted protocol.

The equipment can carry on the simple application layer attack protection, realizes the partial proxy service type firewall function.

The ability of a device to mask the address of a communication, based on business needs, user security needs, and operational requirements.