FI107099B - Routing between telecommunications networks - Google Patents

Abstract

The present invention relates to a method of routing a call between a circuit switched network and a packet switched network in a network system comprising a media gateway between the circuit switched network and the packet switched network. In the method all routing procedures for the call are handled by a separate routing controller common for several media gateways. The invention relates further to an arrangement for performing the same.

Description

107099

Routing between telecommunications networks Routing mellan communications

Field of the Invention

The invention relates to a routing method in telecommunications networks and more particularly to a method for routing between a telephone network and a data network. The invention further relates to an arrangement for performing routing functions between two different networks.

Background of the Invention

The communication path or bus between two different communication networks requires an interface gateway or access node. For example, an interface access node is needed in cases where one network is a telephone network such as a Public Switched Telephone Network (PSTN) and the other network is a data network such as a packet switched data network (PSDN). Examples of packet switched networks are the global Internetless connection using the TCP / IP protocol suite and various intranet applications.

One possibility to implement an Access Node (AN) between the PSTN and a packet switched data network. * · Is a routing device called a Network Access Server (NAS). A NAS can be defined as a device that receives calls from a PSTN and converts calls to the IP packet format of the Internet.

2 107099 At least some degree of routing operation is required in a telecommunications network arrangement for transferring data packets over a data network so that data packets can be sent to the next correct router and ultimately to the correct destination address. This implementation of functions is usually integrated into the NAS, or else all traffic passes through a separate router specifically and exclusively configured to perform routing tasks. Routing protocols based on international agreements are used to provide this functionality. .Routing protocols are used to dynamically adapt to changes in network structures and also to possible interruptions during different stages of data packet transmission.

Summary of the Invention

Routing protocols, such as OSPF (Open Shortest Path First) and BGP (Border Gateway Protocol), are quite complex and not particularly well suited to simple ones. · Network elements that the NAS would otherwise use. Therefore, integrating routing protocols with each NAS unit in the network system is in most cases a very complex task, and. otherwise requires unneeded changes and / or additional hardware and / or software implementations for each access server on the system.

In the case of using separate routers, routing causes one extra step and each packet has to be processed once more on the NAS. This can cause delays in traffic and increase the risk of interference.

3 107099

Current developments are leading to a model where PSTN network control is separated from NAS to a Signaling Gateway (SG) (from SS7 to ISUPr over IP) and a Media Gateway Controller (MGC), which provides control over the PSTN call, leaving the NAS only as a simple Media Gateway (MG). Typically, the MG contains only one generic DSP (Digital Signal Processor), which can be dynamically programmed to generate a modem or codec for voice over IP. This greatly simplifies the structure of the MG (i.e., the access node for the media), but does not solve the routing problem.

The object of the invention is to overcome the drawbacks of prior art solutions and to provide a new type of solution for routing calls between different networks.

Another object of the invention is to provide a method and arrangement by which the structure of the access node can be simplified and unnecessary duplication of data packets can be avoided.

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According to a first aspect, the objects are achieved by a method of routing a call between a circuit switched network and a packet switched network in a network system comprising a media gateway between a circuit switched network and a packet switched network.

The routing controller may provide routing information about the call traffic destination to the appropriate media gateway. The routing information may comprise the IP interface to be used and the IP address of the next router in the packet switched network. The routing controller for the packet switched network and the signaling controller for the circuit switched network may also form a symmetric structure with respect to the media gateway. The call can be initiated from both the circuit switched network and the packet switched network.

In another aspect, the invention provides an arrangement in a telecommunications network system comprising: a circuit switched network; a packet switched network; multiple media gateways between networks; a signaling controller for processing circuit switched traffic; and a separate routing controller for handling packet switched traffic routing, said separate routing controller being common to said plurality of media gateways.

The routing controller and signaling controller may form a symmetrical structure with respect to the media gateway. The plurality of media gateways can also be arranged in a stack.

In yet another aspect, the invention provides a routing controller for a communication network system comprising a circuit switched network, a packet switched network, a plurality of network gateways and a signaling controller for handling circuit switched traffic, wherein the routing controller is configured to is common to numerous media gateways.

The invention provides numerous advantages because the solution · provides a simplified structure for a media gateway between different telecommunications networks. Because the required media gateway hardware is simpler than prior art solutions, it is therefore more economical and also more reliable in use and less vulnerable to hardware and / or software failures. The proposed solution does not adversely affect the performance of the system or the implementation of its functions, since traffic is separated at different outgoing interfaces. The proposed system is well adapted to any dynamic changes in the network system. In addition, the invention makes it easier to stack media gateway units in a small space.

In the following, the invention and its other objects and advantages will be described by way of example with reference to the accompanying drawings, in which various features throughout the drawings refer to like features using like reference numerals.

Brief Description of the Drawings

Fig. 1 is a schematic representation of a network system having a voice network and a data network and interconnecting hardware therebetween; and Figure 2 illustrates a signaling current according to one embodiment of the invention.

Detailed explanation of the drawings

Figure 1 is a schematic representation of a single network system including a PSTN 1, an IP network 2 (e.g., TCP / IP Internet or an intranet application) and a communication node or gateway hardware between them. The arrows indicate the signaling directions> - in the situation where the call was initiated by the PSTN terminal (not shown). In this example, the gateway apparatus comprises a plurality of media gateways 3, 3 ', a signaling gateway SG (conversion from SS7 to ISUP through IP), and a media gateway controller MGC 4 that handles call-related control.

Each MG 3, 3 'can contain only one generic DSP (Digital Signal Processor) that can be dynamically programmed to form a codec of audio transmitted via modem or IP. Thus, the structure of MG can be substantially simplified, which significantly reduces the cost of MG and also improves the reliability of MG. As discussed, MGs can be stacked in a substantially dense space, just like conventional telephone exchanges. It should be noted that although only two MGs are shown in Figure 1, their number could be substantially higher.

The gateway hardware further has a separate routing controller RC 5, the arrangement being such that the routing to the routing controller 5 is separated similarly to the signaling gateway and media gateway controller 4. In other words, the system is "symmetric" to PG: id to MG: id and from an IP network perspective. Thus, the previous access servers are now simplified to form only media gateway units 3, 3 '.

Similar to the SG + MGC 4, the routing controller 5 is common to several media gateway units 3, 3 '. The routing controller 5 is configured to communicate with the IP network 2 using appropriate routing protocols such as OSPF and BGP and to provide the necessary routing commands to the appropriate media gateway unit 3, 3 '. The main information required by the appropriate media gateway '* - is the current status of the traffic destination, which 7 107099 traffic originates from the PSTN side and comes through a designated PSTN line. The information required typically consists of an indication of the correct IP interface to use and the IP address of the next router (i.e., the next "hop" in the data network).

An example of routing protocols is the OSPF routing protocol (RFC2178), which is one of the IP protocols, more specifically IP protocol number 89. All IP packets that enter the media gateway MG and are protocol 89 are tunneled to the router controller. The routing controller 5 sees each MG interface as its own interface, and when something is sent to the RC interface, it is tunneled to and transmitted to the MG. There are five types of OSPF packets, all of which must be compatible with an IP packet size of 576 bytes (if used in accordance with Appendix A to RFC2178). Another typical protocol is RIP (RFC1723), which is a UDP based protocol (transport layer datagram layer over IP layer, port 520). A similar tunneling approach also applies here when traffic from the UDP port 520 is forwarded to the routing controller.

The media gateway unit MG can be made as simple as possible by eliminating both IP routing processing and call routing. This does not seem harmful. because it separates traffic into different outbound (egress) interfaces in a router-like manner. The system also adapts to any dynamic changes in the network like a router.

PSTN users often have a dynamically assigned IP address.

»In this case, the RC must" advertise "8 107099, so other system routers can send data packets to the correct MG.

It is also possible that the user of the PSTN has a known IP network address or IP network subnet. In this case, the RC may call back the PSTN phone number associated with this IP address when someone attempts to access that IP address from the IP network side. If the connection is already established, this case is similar to the one discussed above.

RC announces routes to fixed network addresses even in high-profile cases when connections are down, thus disconnected. The RC can accomplish this by using one, some, or available ports based on local operating principles (for example, some MGs may be located closer to their destination in the PSTN). When a packet addressed to a predetermined destination arrives, the MG routes it to a special dynamic interface that causes the SG to make the requested call. This may involve utilizing one additional server, such as an AAA server (Authentication, Authorization and Computing Server).

Authorization and Accounting server); For the AAA server, the most commonly used protocol is RADIUS), which maintains customer information in a database common to SC and RC.

Figure 2 shows signaling currents 11 to 13 (circled numbers) in connection with the solution described above. At point 11 in the stream, the AAA server 7 defines fixed paths, and the RC 5 ensures that the MG 3 receives the address notification and initiates the MG 3 to initiate the connection, if any, upon arrival of the data packet. At step 12 of the stream, a data packet arrives, after a minimum of 9 107099, the MG 3 contacts the SG / MGC 4 to establish a connection. SG 4 requests the telephone number from AAA server 7 and connects to that number. The MG 3 then forwards the data packet to the established connection 13. In the event that the same route is reported in multiple MGs, in most cases, it is necessary to ensure that only one connection is established at a time. However, there may be cases where multiple connections would be desirable, e.g., to allow the user to receive multiple calls at the same time and / or to increase bandwidth and / or to target the call to multiple geographically different locations simultaneously.

The invention thus provides a device and method for providing a significant improvement in the field of routing between different networks. It should be noted that the above exemplary embodiments are not intended to limit the scope of the invention to the specific embodiments set forth above, but rather that the invention is intended to cover all modifications, similarities, and variations contained within the spirit and scope of the invention. as defined by thymes.

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Claims (12)

A method of routing a call between a circuit switched network (1) and a packet switching network (2) in a network system, which network system includes a media gateway (3) between the circuit switched network (1) and the packet switching network (2) , characterized in that the routing procedures for the call are handled by a separate routing controller (5) common to several media gateways (3, 3 '). Method according to claim 1, characterized in that the routing controller (5) provides routing information regarding the destination of the call traffic to an appropriate media gateway (3). Method according to claim 2, characterized in that the routing information comprises the IP interface to be used and the IP address of the next router in the packet switching network (2). Method according to any of the preceding claims, characterized in that the routing control unit (5) for the packet switching network (2) and the signaling control unit for the circuit switched network (1) form a symmetrical structure in relation to the media gateway (3). Method according to any of the preceding claims, characterized in that the call comes to the media gateway (3) „from the side of the circuit-switched network (1). Method according to any of claims 1 to 4, characterized in that the call arrives at the media gateway (3) from the side of the packet switching network (2) and is destined for a terminal connected to the circuit switched network (1). Method according to claim 6, characterized in that, in the event that the terminal has a dynamically assigned IP address, the terminal IP address is announced by the routing controller (5) to the system routers. Method according to claim 6, characterized in that, in the event that the terminal has a known IP address, the routing controller (5) calls back to a number associated with said IP address for the dialed circuit switched terminal. An arrangement in a communication network system, the arrangement comprising: a circuit-switched network (1); a packet switching network (2); a plurality of media gateways (3, 3 ') between the networks; a signaling controller for the management of circuit-switched traffic; characterized in that it comprises a separate routing controller (5) for handling packet switching traffic routing, said routing controller (5) being common to said plurality of media gateways (3, 3 '). * 4 Arrangement according to claim 9, characterized in that the routing controller (5) and the signaling controller form a symmetrical structure in relation to the media gateway (3). 107099 Arrangement according to claim 9 or 10, characterized in that the plurality of media gateways (3, 3 ') are arranged in stack. A routing controller (5) for a communication network system, comprising a circuit switched network (1), a packet switching network (2), a plurality of media gateways (3, 3 ') between the networks, and a signaling controller for handling circuit-switched traffic , characterized in that the routing controller (5) is arranged to form a separate routing controller (5) to handle packet switching traffic so that said separate routing controller (5) is common to said plurality of media gateways 3, 3 '). ► ·