Abstract:
According to the present invention, a switching method and a switching device ( 3 ) are disclosed for providing a multilink connection between a subscriber ( 1 ) and a network ( 2 ), the multilink connection consisting of a plurality of physical connections taken by the subscriber ( 1 ). The switching device ( 3 ) comprises a plurality of converting means ( 34, 35 ) each converting, upon activation, physical connections into a logical connection to the network ( 2 ) and converting a logical connection from the network ( 2 ) into physical connections. Furthermore, the switching device ( 3 ) comprises control means ( 31, 32, 33 ) for accepting a connection from the subscriber ( 1 ), for detecting that the connection is a physical connection belonging to a multilink connection, for activating one of the converting means ( 34, 35 ) for the detected multilink connection, and for directing the accepted connection and subsequently accepted physical connections belonging to the detected multilink connection to the converting means ( 34, 35 ) activated for this multilink connection.

Description:
PRIORITY CLAIM 
   This is a national stage of PCT application No. PCT/EP99/10475, filed on Dec. 30, 1999. Priority is claimed on that application. 
   FIELD OF THE INVENTION 
   The present invention relates to a switching method and a switching device for providing a multilink connection between a subscriber and a network, the multilink connection consisting of a plurality of physical connections taken by the subscriber. 
   In particular, the present invention is related to a device that connects subscribers of a telephone network, for example PSTN (Public Switched Telephone Network), ISDN (Integrated Service Digital Network), GSM (Global System for Mobile Communications) and WCDMA (Wideband Code Division Multiple Access) to Internet. 
   BACKGROUND OF THE INVENTION 
   In general, AS (Access Server) devices support multilink connections from subscribers of a telephone network to a packet switched network like the Internet. A multilink represents connections in which a subscriber uses several physical links within one logical connection to the Internet. When forming multilink connections, the major problem is that typically the physical connections between the subscriber and the AS device are terminated in different hardware entities at the AS device. 
   However, because of packetization of user data to a single logical Internet connection, the several physical connections used for the single logical connection actually have to be terminated at one hardware entity at the AS device. Thus, forming one logical connection consisting of different physical connections can be handled only by using tunneling protocols. For example, in case of multilink connection containing two physical connections, the first physical connection is tunneled from the hardware entity of the AS device at which it is terminated to the hardware entity of the AS device at which the second physical connection is terminated. This tunneling may use either internal transmission paths of the AS device or the Internet itself. 
   However, the above-described tunneling method raises several problems. The tunneling of user data from one hardware entity of the AS device to another increases the load of these elements. Moreover, using the Internet for tunneling the user data, unmanageable problems may occur because of unpredictable behavior of the Internet. 
   SUMMARY OF THE INVENTION 
   Therefore, it is an object of the present invention to provide a device for supporting multilink connection to a network, in which device no tunneling between hardware entities has to be performed. 
   This object is achieved by a switching device for providing a multilink connection between a subscriber and a network, the multilink connection consisting of a plurality of physical connections taken by the subscriber, comprising:
         a plurality of converting means each converting, upon activation, physical connections into a logical connection to the network and converting a logical connection from the network into physical connections; and   control means for accepting a connection from the subscriber, for detecting that the connection is a physical connection belonging to a multilink connection, for activating one of the converting means for the detected multilink connection, and for directing the accepted connection and subsequently accepted physical connections belonging to the detected multilink connection to the converting means activated for this multilink connection.       

   In addition, this object is achieved by a switching method for providing a multilink connection between a subscriber and a network, the multilink connection consisting of a plurality of physical connections taken by the subscriber, comprising the steps of:
         accepting a connection from the subscriber;   detecting that the connection is a physical connection belonging to a multilink connection;   activating one of a plurality of converting means for the detected multilink connection, each converting means converting, upon activation, physical connections into a logical connection to the network and converting a logical connection from the network into physical connections; and   directing the accepted connection and subsequently accepted physical connections belonging to the detected multilink connection to the converting means activated for this multilink connection.       

   According to the present invention, the QoS (Quality of Service) of multilink connections can be enhanced due to the fact that tunneling delays are eliminated. Furthermore, the load relating to the control of multilink connections and consumption of resources can be decreased. 
   In the following, the present invention will be described by way of a preferred embodiment thereof with respect to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a schematic block diagram illustrating a system and communications performed in the system including a switching device according to a preferred embodiment of the present invention. 
       FIG. 2  shows a flow chart illustrating the operation of the switching device of  FIG. 1  according to the preferred embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows a schematic block diagram of a system including a switching device  3  according to the preferred embodiment of the present invention. The features of the switching device  3  may be implemented in an Access Server device (AS device), for example. 
   In  FIG. 1  a subscriber  1  of a telephone network like PSTN, ISDN, GSM and WCDMA connects to a packet-switched network  2  like the Internet via the switching device  3 . 
   The switching device  3  comprises a connection entity  31  which handles connections between the subscriber  1  and the switching device  3  as well as internal connections of the switching device  3 . The switching device further comprises a PPP-instance PPP-X  32  representing a free PPP-instance to which the connection entity  31  connects first. PPP means point-to-point protocol which is a method for transmitting datagrams over serial point-to-point links. Thus, a PPP-instance is a node in the switching device  3  which adapts the point-to-point protocol. 
   As shown in  FIG. 1 , the switching device  3  also includes a bundle manager  33  which handles multilink connections of the switching device  3 . The bundle manager  33  is aware of multilink connections of the system of  FIG. 1  and corresponding states. In addition the bundle manager  33  controls a multilink pool  35 . 
   The multilink pool  35  inside the switching device  3  comprises a plurality of PPP-instances PPP- 1 , PPP- 2 , . . . , PPP-N which form hardware entities reserved for multilink usage. In  FIG. 1 , two PPP-instances PPP- 1  and PPP- 2  are shown for a multilink connection consisting of two physical connections forming one logical connection to the network  2 . In particular, PPP- 1  and PPP- 2  form one hardware entity which connects to a corresponding multilink entity  34 . 
   The multilink entity  34  handles the subscriber&#39;s multilink service. The multilink entity  34  gathers the subscriber&#39;s physical transmission links of the same hardware entity (PPP- 1  and PPP- 2  in  FIG. 1 ) to one logical connection to the network  2  and vice versa. 
   In the following, the communications performed in the system of  FIG. 1  will be described. 
   In case the subscriber  1  takes a first physical connection to the switching device  3  by means of the connection entity  31  (C 1 ), the connection entity  31  forms a connection to a free PPP-instance located inside the switching device  3  (C 2 ). Here, the free instance is called PPP-X. PPP-X is not located in the multilink pool  35 . The default is that the connection taken by the subscriber  1  is not multilink type. PPP-X detects that the subscriber asks for multilink service and, hence, informs the bundle manager  33  of the multilink connection request (C 3 ). The bundle manager  33  has information of all multilink connections of the whole system. It is able to find out, for example on the basis of user information (e.g. username of the subscriber), that the subscriber in question has no previous resources reserved, i.e. that the connection request of the subscriber  1  is the first physical connection of a multilink connection to the switching device  3 . 
   After having checked the resources of the subscriber  1 , the bundle manager  33  informs the PPP-instance PPP-X to forward the information to the connection entity  31 , which information is required for resource reservation from the multilink pool  35  (C 4 ). Because the first physical connection equipped with multilink information of the subscriber  1  is in question, the bundle manager  33  has to start an object, i.e. the corresponding multilink entity  34 , which has to handle the bundling of multilink connections (C 5 ). 
   PPP-X transmits the multilink pool information received from the bundle manager  33  and previously negotiated PPP-parameters to the connection entity  1  (C 6 ). After that the connection entity  31  is able to form a connection to a PPP-instance reserved from the multilink pool  35 . In this case, the connection entity  31  forms a connection to PPP- 1  and transmits the parameters received from PPP-X to PPP- 1  (C 7 ). This allows PPP- 1  to start up to the same state as which was state of PPP-X. Now, PPP- 1  is ready to transmit traffic to the multilink entity  34  (C 8 ), which traffic is transmitted to the network  2  by the multilink entity  34  (C 9 ), so that traffic between the subscriber  1  and the network  2  can be transmitted. 
   Next, the subscriber  1  takes another physical connection of the same multilink connection to the switching device  3  through the connection entity  31  (C 10 ). Again, the connection entity  31  forms a connection between the subscriber  1  and a free PPP-instance (PPP-X) of the switching device  3  (C 11 ). Again, multilink requirement is found out. 
   PPP-X informs the bundle manager  33  of the connection requirement (C 12 ). The bundle manager checks on the basis of information about all multilink connections of the system whether the subscriber  1  has previous resources reserved. The bundle manager  33  is able to find out, on the basis of identification information (e.g. username of the subscriber), that the subscriber  1  in question already has reserved resources, reserved from the multilink pool  35  and from the certain physical hardware entity formed of PPP- 1 . Thus, the bundle manager  33  reserves a resource for the other physical connection, which resource is located at the same hardware entity as the resource PPP- 1  of the first physical connection. After the reservation, the bundle manager  33  informs the PPP-instance PPP-X that the reservation has been performed (C 13 ). 
   PPP-X transmits the multilink information received from the bundle manager  33  together with parameters negotiated by PPP-X to the connection entity  31  (C 14 ). This enables the connection entity  31  to form a connection to a PPP-instance reserved from the multilink pool  35 . According to  FIG. 1 , the connection entity  31  forms a connection to PPP- 2  and transmits the parameters received from PPP-X to PPP- 2  (C 15 ) so that PPP- 2  starts up to the similar state as PPP-X was. 
   Thus, PPP- 2  located at the same hardware entity as PPP- 1  is ready to transmit traffic to the same multilink entity  34  as PPP- 1  (C 16 ). The multilink entity  34  transmits the traffic of the second physical connection to the network  2  (C 17 ). Therefore, the multilink entity  34  is able to transmit traffic between the subscriber  1  and the network  2  using a single network address, although two physical connections are used. 
   As described above, using the multilink pool  35 , multilink connections of a plurality of subscribers can be directed to the respectively same hardware entity which in turn is in connection with one corresponding multilink entity  34 . 
   The physical connection amount from the subscriber  1  to the multilink entity is not restricted to two, but in case more physical connections are taken into use, the communication parts C 10  to C 17  have to be repeated. In the example shown in  FIG. 1 , the PPP-instances PPP- 1  and PPP- 2  of the multilink pool  35  are located at the same hardware entity. This is important when terminating connections, which are actually going through different PPP-instances, at a single multilink entity. 
   With reference to the flowchart shown in  FIG. 2 , the operation of the switching device  3  will be described in a more general way. 
   When the switching device  3  of  FIG. 1  receives a (physical) connection request from the subscriber  1  (step S 1 ), it checks whether the requested connection belongs to a multilink connection which is already established between the subscriber  1  and the network  2  by means of the switching device  3 . 
   If it is detected in step S 2  that the connection represents a new multilink connection to be established between the subscriber  1  and the network  2 , the switching device  3  starts a new or free multilink entity  34  for the new multilink connection (step S 3 ). Then, a new or free PPP-instance (PPP- 1  in  FIG. 1 ) is reserved for the requested physical connection at a new hardware entity (step S 4 ). As a result, the connection between the subscriber  1  and the network  2  is established via the hardware entity and the multilink entity for this hardware entity so that traffic can be transmitted between the subscriber  1  and the network  2  (step S 5 ). 
   In case it is detected in step S 2  that the requested connection belongs to an already established multilink connection, this multilink connection is determined (step S 6 ) as described in connection with  FIG. 1 . Then, a free PPP-instance at the already existing hardware entity for the established multilink connection is reserved (step S 7 ). According to  FIG. 1 , PPP- 2  is reserved for the connection C 10  at the same hardware entity to which PPP- 1  belongs. As a result, the connection is established between the subscriber  1  and the network  2  via the existing hardware entity and the corresponding multilink entity  34  (step S 5 ) which has been started already for the multilink connection to which the physical connection belongs. 
   According to the present invention, the use of tunneling protocols for tunneling physical connections from one hardware entity of the switching device to another hardware entity can be avoided. 
   In view of this fact, the QoS (Quality of Service) of multilink connections can be enhanced and the load relating to the control of multilink connections and consumption of resources can be decreased. 
   While the invention has been described with reference to a preferred embodiment, the description is illustrative of the invention and is not to be construed as limiting the invention. Various modifications and applications may occur to those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.