Softswitch

1, introduction

With IP network technology unceasing development mature, traditional telecom business to IP network transfer has been formed an irreversible trend. But the soft exchange packet-based teleportation network the architecture just caters to the IP network rapid development trend. Use the soft exchange form a next-generation network, provide voice/data/image comprehensive services, and becomes the focus of the telecom operators to consider.

The soft exchange due to its terminal equipment cloth simple, business development quick wait for a characteristic, both at home and abroad at present already have plenty of application. How to use the soft exchange equipment quickly provide currently in existing network realization difficult operations, as well as how to conduct the soft exchange network organization in order to adapt to the characteristics of the data network problems such as industry discussed more topics.

In this paper, the soft exchange network system of network organization problem for technical research and discussion.

1, routing server (RS) of introduction

In PSTN network, USES hierarchical network architecture, switching equipment according to different locations are divided into the bureau switches, consequently switches, long distance switch level 3. In a call, signaling and media are adopted the forwarding way, consequently near-line and long-distance switches also end and the media, so consequently signaling and long distance telephone switches realized the convergence and relaying resource sharing function. In routing has direct route and circuitous route of points, on a target bureau can select routing number five biggest can reach.

The soft exchange network system, gateway between bearing is to use media end-to-end way, but the soft exchange agreement between the news may be end-to-end, also can through the midst of the soft exchange forwarding specially consequently. But, given a packet network service quality best, such as no characteristic, should consider to minimize in networking protocol among forwarding number. News

Therefore, the concept of softswitch network routing with PSTN network are quite different, which have no direct route and circuitous route of points, aimed at a call of the target bureau will only a routing, namely the next-hop soft exchange (may be called in the soft exchange, also may be the soft exchange among consequently). In the soft exchange network reaches a certain scale, if the soft exchange between reticular connection, route data would be very huge, through the soft exchange itself thinning routing configuration difficult to achieve. It is necessary to introduce large capacity, high-performance Server dedicated Routing analytical work, this paper assumes unified called Routing Server (RS:) and its function are Server (equal to TRIP over IP Telephony ccna) in the agreement of position Server (LS: Location Server).

3, the soft exchange network structure

3.1 steplessly nets

All the soft exchange network originating in the same plane and the soft exchange directly route to accept the soft exchange, the soft exchange between is a mesh network structure. The soft exchange network routing information stored in RS, RS can divide between regional classification configuration, RS can realize routing information query and dynamic routing update.

3.1.1 network structure

RS is divided into two layers, among them, 1) provincial RS storage of information including attached to it the soft exchange user information (for example SIP address, e. 164 address), and the soft exchange address information; Other provincial RS address and user information. 2) national RS stored information including provincial RS address and user information.

Based on RS complete routing synchronous, save A soft exchange A user A need and provincial B softswitch B user B calling, concrete process is as follows:

1) A soft switching to A province RS_A inquires the user B positional information, 2) RS_A RS_B inquires the user to the position information of B, 3) RS_B RS_A back to user B belongs to the soft exchange B address information, 4) soft switching to A soft switch B send SIP signaling, request to establish the call.

3.1.2 advantages and disadvantages:

Advantages: 1) the soft exchange by RS can directly routing to destination the soft exchange, to avoid the call signaling message in IP forwarding the many times handles, 2) route data concentrated Settings, unified management, a soft switching routing information update, can pass TRIP such agreement timely radio to other RS, facilitate route data of configuration management. Inadequate: 1) be fitted with series of RS, network construction cost is higher, the initial can consider RS and the soft exchange collaboration to reduce the construction cost, 2) all calls to RS inquires to route data, the soft exchange system processing efficiency has certain influence; 3) due to different manufacturers adopt the strategy, protocols, there are differences currently equipment interchange difficulties.

3.2 grading nets

Call control protocol message through multiple softswitch switchboard, media is end-to-end connection. The soft exchange can be divided into the local service softswitch and provincial consequently the soft exchange two levels. The local service the soft exchange is responsible for service area users provide rich business, including voice/data/image of integrated business etc. The soft exchange responsible for provincial consequently the soft exchange of provinces, which consequently business, mainly responsible for routing and protocol connecting, do not need to control gateway device on the media connection.

3.2.1 network structure

The routing server has the following requirements: 1) route data storage, responsible for providing the soft exchange between the local provincial end-to-end routing information, and local provincial soft soft switching to the routing information exchange, 2) local softswitch route data changes need only with the provincial RS synchronization; Provincial the soft exchange data changes, needs and other provincial RS synchronously. 3) called for the same address, can according to initiate queries softswitch level different return different routing information. As for a local call, the province, the soft exchange inquires the soft exchange for provincial results returned the IP address of the soft exchange inquires, provincial, returns to end inter-province softswitch IP address information.

Based on RS complete routing synchronous, save A soft exchange A user A need and provincial B softswitch B user B calling, concrete process is as follows:

1) save A soft switching to A local RS_A inquires the user B positional information, 2) RS_A soft exchange A return to the local provincial soft exchange A 'address information, 3) to RS_A provincial soft exchange A 'send SIP news, request call succeeded, 4) provincial soft exchange A 'receives SIP news, inquires the RS_A, request users of B routing information. 5) to RS_A provincial soft exchange A 'return inter-province soft switch B' address information, 6) provincial soft switching to A 'provincial soft switch B' send SIP news, request call succeeded, 7) provincial soft switch B 'receives SIP news, inquires the RS_B, request users of B routing information, 8) to RS_B provincial softswitch B 'return to local soft switch B address information, 9) provincial softswitch B 'to the local softswitch B send SIP news, request call succeeded.

3.2.2 advantages and disadvantages:

Advantages: 1) only through the soft exchange and outer net provincial communication can shield province the soft exchange network condition, safety is better; 2) using RS mechanism, can pass TRIP agreements on the flexible management domain routing information.

Inadequate: 1) trans-provincial call agreement information need to pass more paragraphs forwarding, to a packet network reliability requirements increased, 2) to call in the time and other related services quality may have certain effect, 3) provincial softswitch planning to consider when capacity, safety backup and so on the related question.