WO2012072920A1

WO2012072920A1 - Method and device for managing a subscription to a service in an ims network

Info

Publication number: WO2012072920A1
Application number: PCT/FR2011/052759
Authority: WO
Inventors: Bertrand Bouvet
Original assignee: France Telecom
Priority date: 2010-11-30
Filing date: 2011-11-25
Publication date: 2012-06-07
Also published as: FR2968158A1

Abstract

The invention relates to a method for managing a subscription to a service in an IMS network, which comprises: a step (E5) of creating at least two subscription files for a given public identity, each of which is associated with a subscription size and policy; a step (E10) of receiving a message of subscription to said service sent by a terminal having said public identity; and a step (E10) of assigning one of said subscription files to said terminal for said service on the basis of an indicative parameter contained in a field of said subscription message.

Description

Method and device for managing subscription to a service in an IMS network

Background of the invention

The invention is in the field of IMS (IP Multimedia Subsystem) type telecommunication networks as defined by the 3GPP (Third Generation Partnership Project).

One of the goals of the IMS is to allow a user to access different services regardless of their type of IP connectivity.

IMS networks, initially designed for mobile networks, tend to develop on fixed access networks such as ADSL (Asymmetric Digital Subscriber Line) or FTTH (fiber to the home), or cable networks in particular.

In particular, the IMS architectures for fixed networks have been deployed for the marketing of so-called "Multiplay" offers allowing a user to access various services of the IMS network, and in particular to access services to the Internet, to voice IP (VoIP) and Internet TV (IPTV) via a home gateway.

In order to diversify their offer, telecommunications operators offer terminals complementary to fixed telephones, these additional terminals being equipped with voice over IP (VoIP) software using the same public identifier IMPU as that of the home gateway and a private identifier. IMPI may or may not be the same as the home gateway.

To register at the heart of the IMS network, a terminal (called the User Agent in the document RFC3261) sends, to a server S-CSCF (Serving Call State Control Function) responsible for the records, a registration request including the two identifiers IMPU and IMPI supra.

In addition to the SIP registration required to establish a multimedia session, some IMS services require the terminals to subscribe to certain services, for example to a presence service or to a message deposit notification service called "Message Waiting Indicator". MWI).

The subscription by the terminal to each of these services uses the SIP message (SUBSCRIBE).

In a known manner, this message includes event identifiers associated with the services. The subscription mechanism is specified at the IETF level in RFC3265 and the different event information must be declared to the Internet Assigned Numbers Authority.

Terminals wishing to subscribe to at least one service (called Subscriber in RFC3265) must therefore send a SIP SUBSCRIBE message to an entity, usually an application server, hosting the service, this application server AS being called Notifier in RFC3265.

As an example of an application server, mention may be made, for example, of message waiting notification application servers Message Waiting Indicator and presence application servers.

Figure 1 describes an architecture implementing a service subscription mechanism in an IMS network.

The HGW home gateway provides voice over IP service from a TEL home phone, which in this example is a DECT compliant phone.

The home gateway HGW receives in its VoIP configuration file its VoIP subscription parameters and in particular its public entity IMPU.

The home gateway HGW connects via an access network RA, for example of the ADSL type, through a first DSLAM type network equipment, which is itself connected to an RC collection network, for example to ATM or Giga Ethernet type which allows it to reach a RO operator network through a first RI router.

The RO operator network, of the back bone IP type, makes it possible to reach the entry point of the IMS network via a second router R2.

In known manner, the entry point of an IMS network is a so-called "edge" entity, referenced EB in FIG. 1, which may be constituted by:

- SBC (Session Border Controller) equipment;

a P-CSCF server;

- Equipment fulfilling both the functions of an SBC equipment and those of a P-CSCF server.

In the remainder of this document, the term "border entity" will refer to any of these three devices.

The IMS network comprises in particular the functional entities P-CSCF, I-CSCF, S-CSCF, SLF, HSS, and DNS ENUM known to those skilled in the art.

In the example described here, the IMS network is interconnected with an AS application server offering a message deposit notification service. In the example of FIG. 1, two terminals, namely two mobile VoIP terminals SPl and SP2, are connected to the home gateway HGW by a wireless connection WIFI and use the same public identity IMPU as the HGW gateway.

Each of the SIP terminals (HGW gateway, voice over IP terminals SP1, SP2) requests a subscription to the services provided by the application server AS, which requires managing the subscription contexts associated with the services, within:

- each terminal;

- intermediate equipment (EB border entity and / or S-CSCF server); and

- the AS application server.

In known manner, a SIP SUBSCRIBE message sent by a terminal includes information from the VoIP configuration file transmitted to the terminal; and especially :

- the public identity IMPU;

- the domain name of the IMS network;

the URI (Uniform Resource Identifier) allowing access to the service provided by the application server AS;

dynamic information obtained by the network, including the IP address, the port number, the UDP or TCP transport protocol of the entry point EB of the IMS network;

- static information provided by the terminal equipment; and

dynamic information managed locally by the terminal.

The first SUBSCRIBE subscription message sent by a terminal to subscribe to a service is called the initial subscription message.

This subscription message is routed to the IMS core network either directly at the P-CSCF or through the EB boundary entity and, if all conditions are met, this message is routed by the S-CSCF to the application server concerned.

In known manner the application server concerned responds to the subscription message by a message type 200 OK containing the value of the subscription period (Expires parameters).

The application server then immediately transmits to the terminal a NOTIFY notification message providing the status of the information related to the services associated with the event information; this NOTIFY message is acknowledged by the terminal by a message of type 200 OK. As is known, after the initial subscription the terminal must renew the subscription to the services before the expired value expires. This renewal is carried out according to the same principle as the initial subscription, namely by the sequence of messages SUBSCRIBE, 200 OK, NOTIFY, 200 OK.

This is called subsequent subscription.

Subsequent messages retain the same SIP dialog identifiers as the initial subscription message and increment a CSeq field from 1 to each new submission.

When an event has to be notified to the terminal, the application server AS transmits, on its own initiative, a SIP NOTIFY message containing the event intended for the terminal, this SIP message being acknowledged by the terminal by the sending of a message 200 OK.

In a known manner, to de-subscribe to a service, the terminal can send to the application server AS a SUBSCRIBE SIP message containing the Expires field set to 0, which responds to this message by sending a message 200 OK, then sends the terminal a NOTIFY notification message containing the end of subscription to the service, this notification message being also acknowledged by the terminal by sending a 200 OK message.

Similarly, at any time, an application server AS can notify the terminal that a service is no longer available by sending a notification message SIP NOTIFY containing the end of the subscription to the service, the terminal acknowledging this message by sending a 200 OK message.

The duration of the Expires, setting the duration of subscription to the services is variable. It varies in particular according to the service and the load of equipment.

For example, for the MWI notification service of message delivery within a voicemail, the duration of the Expires can be set to 24 hours and the terminal re-subscribes approximately every 23 hours 50 minutes.

When the home gateway HGW subscribes to a service, a SUBSCRIBE dialogue context is created in each of the devices described with reference to FIG. 1 (HGW gateway, EB edge entity, S-CSCF server and AS application server).

Similarly, when a terminal SP1, SP2 subscribes to a service, a SUBSCRIBE dialogue context is created in each of the devices described with reference to FIG. 1 (terminal concerned, EB edge entity, S-CSCF server and server D AS application). In normal operation, as long as the terminal does not unsubscribe to the service, the contexts are kept end-to-end in each of the entities and self-destruct automatically when the expires time expires.

But, if for some reason or other, the terminal SP1, SP 2 or the HGW gateway is re-registered in SIP core network, after a shutdown without unregistration to the previous service, it re-subscribes to the service but using a new SIP SUBSCRIBE dialog .

As a result, the different equipment traversed (edge entity, S-CSCF server and AS application server) will consume new memory resources to store this new dialogue.

In particular, some home gateways implement monitoring mechanisms to restart the SIP voice over IP stack under certain conditions, for example during a loss of ADSL synchronization or in the absence of a response from a VoIP equipment without taking the time to unsubscribe to the service or to de-register at the core of the IMS network.

Consequently, the subscription mechanism presented above poses problems of memory sizing at the nodes traversed in the network for memorizing the SIP dialogs, this problem being all the more critical as the duration of service subscription expires. is important.

Object and summary of the invention

In general, the invention aims at a subscription management method in an IMS network that does not have the disadvantages of those of the state of the art.

More specifically, and according to a first aspect, the invention relates to a method for managing subscription to a service in an IMS network, these methods comprising:

a step of creating, for a given public identity, at least two subscription queues, each of these queues being associated with a size and a subscription policy;

a step of receiving a subscription message to this service sent by a terminal having this public identity; and

a step of assigning one of these terminal subscription queues for this service on the basis of a discriminant parameter included in a field of this subscription message. Correlatively, the invention relates to a subscription management device for a service in an IMS network, this device comprising:

means for creating, for a given public identity, at least two subscription queues, each associated with a size and a subscription policy;

means for receiving a subscription message to this service sent by a terminal having this public identity; and

means for allocating one of these terminal subscription queues for this service on the basis of a discriminant parameter included in a field of this subscription message.

Thus, in general, the invention proposes to manage the subscription to different SIP services by using several subscription queues.

In order to be effective, the method according to the invention must be implemented in each of the entities traversed and managing the subscription dialogues (EB edge entity, S-CSCF server and AS application server).

The fact of managing several subscription queues makes it possible to define so-called "priority" terminals (such as the home gateway HGW which offers the main telephony service) and to get rid of the hazards due to so-called "secondary" terminals (such as Voice over IP terminals SP1 and SP2).

Moreover, and very advantageously, the fact of managing several subscription queues makes it possible to optimize the memory resources of the various equipment traversed by applying policies adapted to each queue.

In a particular embodiment of the invention, the discriminant parameter chosen to select the subscription queue is chosen from:

an identifier of the service to which the terminal wishes to subscribe;

- an identification token;

- a type of the terminal;

an identifier of the network to which this terminal belongs;

- the parameter q defined in the IETF RFC3261; and

a public identity range IMPU to which the public identity of the terminal belongs.

It will be recalled that the parameter "q" defined by the document RFC3261 of the IETF standard makes it possible to give a priority to a terminal, between 0 and 1, for the function known to those skilled in the art under the name of "forking" when an incoming call to the IMPU is presented to the S-CSCF server. For the purposes of the invention, the specific size associated with each of the queues corresponds to the number of subscription dialog contexts that can be stored in the queue.

Typically, the size of each of these contexts is of the order of 30 KO (kilobytes).

In a preferred embodiment of the invention, each of the subscription queues is further associated with an expires value of expiration of the service. For example, we will choose a value of Expired significant, of the order of 24 hours for the subscription queues assigned to the home gateways and a value of expiration of a few hours for the secondary terminals of voice over IP SP1 and SP2 so in case of loss of WIFI connectivity or malfunction of the non-priority terminal, the memory resources are released much more quickly at the network equipment level.

In one embodiment of the invention, the subscription policy associated with a subscription queue is chosen from:

a first policy (POLA) for which there is no control as to the number of dialogs that can be recorded in the queue:

a second policy (POLB) defining a maximum number of SIP dialogs in the queue, the latter being managed according to a FIFO method (first in first out); and

a third policy (POLC) of rejecting any subscription request in the queue beyond a maximum number of dialogues already recorded in this queue.

With regard to the second policy, several solutions can be envisaged to determine the terminal to be rejected according to the FIFO method. We can choose in particular to reject:

- the terminal of the queue whose subscription is the oldest; or

the terminal of the queue generating the least traffic on the network; or

the terminal of the queue whose parameter q defined in the document RFC3261 is the smallest.

The invention also relates to an edge entity, an S-CSCF server and an application server comprising a subscription management device as mentioned above.

The invention also aims at a subscription message to a service sent by a terminal in an IMS network, this message comprising a selection criterion, for a network identity, a subscription queue among a plurality of subscription queues associated with a public identity of the terminal transmitting the message for this service.

In a particular embodiment, the various steps of the filtering method are determined by computer program instructions.

Consequently, the invention also relates to a computer program on an information medium, this program being capable of being implemented by a computer, this program comprising instructions adapted to the implementation of the steps of the method of management of subscriptions to a service as mentioned above.

This program can use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in a partially compiled form, or in any other form desirable shape.

The invention also relates to a computer-readable information medium, comprising instructions of a computer program as mentioned above.

The information carrier may be any entity or device capable of storing the program. For example, the medium may comprise storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording medium, for example a floppy disk or a disk. hard.

On the other hand, the information medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The program according to the invention can be downloaded in particular on an Internet type network.

Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question.

Brief description of the drawings

Other features and advantages of the present invention will emerge from the description given below with reference to the drawings which illustrate an embodiment having no limiting character. In the figures:

FIG. 1 already described represents an edge entity EB, an S-CSCF server and an application server AS in accordance with a particular embodiment of the invention; FIG. 2 represents the hardware architecture of these entities in a particular embodiment of the invention; and

FIG. 3 represents in flowchart form the main steps of a subscription management method for a service according to a particular embodiment of the invention.

Detailed description of an embodiment

Referring to Figure 2, there is shown the hardware architecture of a subscription management device 10 to a service according to one embodiment of the invention.

In the embodiment described here, this device 10 has the hardware architecture of a computer. It comprises in particular a processor 11, a random access memory of the RAM type 12, a ROM type ROM 13, communication means 14 and a rewritable non-volatile memory 15.

ROM ROM 13 is a recording medium according to the invention. This recording medium is readable by the processor 11 and it stores a PG computer program including instructions for implementing the subscription management method whose main steps are represented in flow chart form in FIG. 3.

This subscription device 10 is incorporated in each of the entities traversed by the subscription messages and manages the SUBSCRIBE dialogs namely, by the EB border entity, by the S-CSCF server and by the application server AS.

In this description, reference 100 denotes any of these entities.

The principal steps E10 to E90 of the process implemented by these entities will now be described with reference to FIG.

This method comprises, a preliminary step E5 creation of subscription queues Fl, F2 and F3, and a default subscription queue FD, in each of the entities EB, S-CSCF and AS.

In the embodiment described here, the subscription queues are stored in the rewritable non-volatile memory 15 of the device 10.

It will be assumed that an entity 100 receives, during a step E10, a SUBSCRIBE SIP subscription message sent by a terminal SP1, SP2 or by the gateway HGW, all these equipments having the same public identity IMPU. During a step E15, the device 10 determines whether the syntax of the SUBSCRIBE subscription message received in step E10 is correct.

If this is not the case, the result of the test E15 is negative and this test is followed by a step E20 during which the entity 100 returns a SIP return code according to the specifications defined in the document RFC3265.

If the SUBS subscription message is syntactically correct, the result of the E15 test is positive and this test is followed by an E25 test in which the entity 100 determines whether it is an EB border entity, an S-CSCF server or a AS application server.

If the entity 100 is an S-CSCF server and the SUBSCRIBE SIP subscription message is configured to be authenticated at the core of the IMS network, the test E25 is followed by an authentication step E30 of the terminal issuing the subscription message.

If this authentication fails, the result of the test E30 is negative and this test is followed by a step E20 sending a SIP return code according to the mechanism described in the document RFC3265.

If the authentication succeeds, the E30 test is followed by an E35 test.

When the entity 100 is an EB border identity or an application server AS, it does not implement the authentication step and the E25 test is followed by this test E35.

During the test E35, it is determined whether the subscription message received in step E10 is an initial subscription message.

If this is the case, this test E35 is followed by a step E40 during which the entity 100 identifies whether the subscription message includes a discriminating parameter enabling it to select one of the subscription queues F1, F2, F3 created at the first time. step E5 for the requested service.

If this is not the case, the result of the test E40 is negative and the default subscription queue FD is allocated, for the requested service, to the terminal sending the subscription message during a step E45.

On the contrary, if the subscription message SUBSCRIBE has such a discriminating parameter, the entity 100 determines the subscription queue Fl, F2 or F3 on the basis of this parameter during a step E50.

During a step E55, the entity 100 determines which subscription policy is associated with the previously determined queue (file Fl, F2, F3 or default file FD). If the subscription policy is the first policy (POLA), the result of the test E55 is followed by a step E70 of creating a SIP dialogue context associated with the subscription message received in step E10.

If the policy of the subscription queue is the second policy (POLB) or the third policy (POLC), the device 10 determines, during a step E60 if the maximum number of subscription dialogs for this queue has been reached.

If this is the case, and if the policy of subscription is the third policy (POLC), then the subscription message received in step E10 is rejected during a step E65 and the device 10 sends for example a code of return 403 Forbidden to the terminal.

If this is not the case, step E60 is followed by step E70 of creating dialogue context.

The dialog context creation step E70 consists of registering a subscription SIP dialogue, for the terminal sending the SUBSCRIBE message received in step E10 and for the service requested by this message.

The step E70 is followed by a step E75 during which the entity 100 determines whether it is constituted by an S-CSCF server, by an application server AS or by an edge entity EB.

If the entity 100 is an S-CSCF server or an EB border entity, the test E75 is followed by a step E80 during which the device 10 relays the SUBSCRIBE subscription message received in step E10 to the downstream node .

If the entity 100 is an application server AS, the test E75 is followed by a step E85 during which the server AS sends a return code 200 OK to the terminal if the service is operational, this message including the value of d expires associated with the queue chosen in step E45 or E50.

Then, during a step E90, the application server AS instantly notifies the sending terminal of the SUBSCRIBE message of the state of the service.

Claims

A method of managing a subscription to a service in an IMS network, the method comprising:

a step (E5) of creating, for a given public identity (IMPU), at least two subscription queues (Fl, F2, F3), each associated with a size and a policy (POLI, POL2, POL3 ) subscription;

a step (E10) of receiving a subscription message to said service sent by a terminal (HGW, SP1, SP2) having said public identity; and

a step (E70) for allocating one of said subscription queues to said terminal for said service on the basis of a discriminant parameter included in a field of said subscription message.

2. Management method according to claim 1, characterized in that said discriminant parameter is chosen from:

an identifier of the service to which said terminal wishes to subscribe;

- an identification token;

- a type of the terminal;

an identifier of the network to which said terminal belongs;

- the parameter q defined in the IETF RFC3261;

a public identity range (IMPU) to which said public identity belongs.

3. Management method according to claim 1, characterized in that each subscription queue is further associated with an expiration value of said service.

4. Management method according to claim 1, characterized in that it comprises a step of assigning a default queue (FD) to said terminal if said message does not include said discriminant parameter.

5. Management method according to claim 1 characterized in that said subscription policy (POLA, POLB, POLC) associated with a subscription queue is selected from:

a first policy (POLA) for which there is no control over the number of dialogs that can be recorded in said queue;

a second policy (POLB) defining a maximum number of SIP dialogs in said queue, which queue is managed according to a FIFO type method; and a third policy (POLC) of rejecting any subscription request in said queue, beyond a maximum number of dialogues already recorded in said queue.

6. The management method as claimed in claim 5, characterized in that said second subscription policy (POLB) consists of rejecting, according to the FIFO method:

the terminal of said queue whose subscription is the oldest; or

the terminal of said queue generating the least traffic on the network; or

the terminal of said queue whose parameter q defined in the document RFC3261 is the smallest.

7. Device (10) for managing subscriptions to a service in an IMS network, this device comprising:

means (11, 12, 13, 14, 15) for creating, for a given public identity (IMPU), at least two subscription queues (Fl, F2, F3), each associated with a size and a policy (POLI, POL2, POL3) underwriting;

means (11, 12, 13, 14, 15) for receiving a subscription message (SUBS) for said service sent by a terminal (HGW, SP1, SP2) having said public identity;

means (11, 12, 13, 14, 15) for allocating one of said subscription queues to said terminal for said service on the basis of a discriminant parameter included in a field of said subscription message.

Border entity (EB) having a subscription management device according to claim 7.

9. S-CSCF server having a subscription management device according to claim 7.

An application server (AS) having a subscription management device according to claim 7.

Subscription message (SUBS) for a service sent by a terminal in an IMS network, characterized in that it comprises a selection criterion, for an entity (EB, S-CSCF, AS) of said network, of a a subscription queue (F1) among a plurality of subscription queues (F1, F2, F3) associated with a public identity (IMPU) of the terminal transmitting said message for said service.

A computer program (PG) comprising instructions for executing the steps of the subscription management method according to any one of claims 1 to 6 when said program is executed by a computer.

13. Computer-readable recording medium (13) on which a computer program (PG) is recorded including instructions for executing the steps of the subscription management method according to any one of claims 1 to 6 .