Patent Publication Number: US-2021195465-A1

Title: Traffic in a distributed cloud system

Description:
TECHNICAL FIELD 
     The present application relates to a method for operating a control entity configured to influence a selection of one service instance from a plurality of service instances provided by a distributed cloud system. Furthermore, the corresponding control entity configured to influence the selection is provided. Additionally a method for operating an exposure entity configured to expose different type of services provided to a mobile entity through a mobile communications network is provided and the corresponding exposure entity itself. Furthermore, a system comprising the control entity and the exposure entity is provided, a computer program comprising program code and a carrier comprising the computer program. 
     BACKGROUND 
     Distributed cloud and edge computing aim at improving latency, security, policy compliance, aggregation, and availability of services by bringing service instances closer to clients in order to keep the traffic path short. To achieve these goals, it is necessary to control where workloads or service instances are placed in the network. It is also necessary to influence application traffic originating from client applications on mobile devices/user entities such that it addresses the server closest to the user entity. To simplify the adoption of edge services it is desirable to do this without making the client device or software aware of the distributed cloud topology or of the way how the packet core works. 
     Existing solutions to influence or intercept application traffic for local processing at service instances exist in following categories:
         Network-wide service chaining including header manipulation. This approach has been pursued in the realm of SDN (Software Defined Network) before with limited success. It leads to complex solutions that rely on policy-based forwarding rather than IP routing and separation of concern between transport network, end devices, and applications.   Global load balancing: distributed load balancing devices at data center locations with synchronization among them, often combined with interception and manipulation of DNS (Domain Name System) queries can be used to steer traffic to the desired service instances. Applying this approach to distributed cloud system likely requires a high number of specialized, costly load balancers across all sites.   Anycast: all instances of the same service reside at the same IP address and routing in the networks makes sure traffic reaches the closest instance (closeness based on routing metrics). Anycast is suitable only for short lived transactions. In case of routing changes in the network, long lived sessions may be routed to a different server that lacks application state (and TCP state) for the ongoing session. This will lead to a failure of ongoing application sessions.   DNS based solutions: use the hierarchical DNS system to return addresses of different service instances depending on where the user is. This can be realized by making users in one region connect to a DNS server in that region which in turn returns addresses of services in the same region (locality). The first problem with DNS based solutions is caching. Some client resolvers cache DNS answers even when the time-to-live has expired, making it impossible to re-direct traffic to another sever reliably. The second disadvantage is the need to deploy and manage one DNS server per Distributed Cloud location. This will present a scaling and maintenance problem when Distributed Cloud sites move closer out in the network and their number increases.       

     Accordingly, a need exists to influence the selection of a service instance in such a way that a service instance is selected among several service instances located close to the user entity requesting the service. 
     SUMMARY 
     This need is met by the features of the independent claims. In the dependent claims further aspects are described. 
     According to a first aspect, a method for operating a control entity configured to influence a selection of one service instance from a plurality of service instances provided by a distributed cloud system is provided. Each service provides a predefined service to a data packet flow of the user entity connected to a mobile communications network. The method comprises the step of monitoring the creation of new service instances providing the predefined service in the distributed cloud system, wherein for each new service instance a corresponding location in the distributed cloud system is determined. Furthermore, for each of the newly created service instances location information is determined indicating for each service instance a corresponding nearest access point to the mobile communications network. The location information is transmitted to the mobile communications network requesting to take into account the transmitted location information for selection of a user plane entity configured to transmit at least a user data plane of the data packet flow between the user entity and one of the service instances. 
     Furthermore, the corresponding control entity configured to influence the selection of the service instances provided, the control entity comprising a memory and at least one processing unit, wherein the memory contains instructions executable by the at least one processing unit. The control entity is operative to work as discussed above or as discussed in further detail below. 
     As an alternative, a control entity configured to influence the selection of one service instance from a plurality of service instances provided by a distributed cloud system is provided, wherein each service instance provides a predefined service to a data packet flow of a user entity connected to a mobile communications network. The control entity comprises a first module configured to monitor a creation of new service instances providing the predefined service in the distributed cloud system, and configured to determine for each of the new service instances a corresponding location in the distributed cloud system. A second module of the control entity is configured to determine, for each of the newly created service instances, location information indicating for each service instance a corresponding nearest access point to the mobile communications network. The control entity furthermore comprises a third module configured to transmit the location information to the mobile communications network requesting to take into account the transmitted location information for a selection of the user plane entity configured to transmit at least the user data plane of the data packet flow of the user entity between the user entity and one of the service endpoints. 
     Furthermore, a method for operating an exposure entity configured to expose different type of services provided to a mobile entity through a mobile communications network is provided, wherein each type of service is provided by a plurality of service instances located in a distributed cloud system. The method comprises the step of receiving a request from a control entity configured to influence a selection of one service instance from the priority of service instances for one type of service, wherein the request comprises location information indicating for one of the service instances a corresponding nearest access point to the mobile communications network. The exposure entity furthermore transmits a request to a subscriber database of the mobile communications network requesting the subscriber database to use the location information for all subscribers requesting the use of said one type of service. 
     Additionally the corresponding exposure entity is provided comprising a memory and at least one processing unit wherein the memory contains instructions executable by the at least one processing unit and wherein the exposure entity is operative to work as discussed above or as discussed in further detail below. 
     As an alternative, an exposure entity is provided configured to expose the different type of services provided to a mobile entity through a communications network, wherein each type of services provided by a plurality of service instances located in the distributed cloud system. The exposure entity comprises a first module configured to receive a request from a control entity configured to influence a selection of one service instance from the plurality of service instances for one type of service, wherein the request comprises location information indicating for one of the service instances a corresponding nearest access point to the mobile communications network. The exposure entity comprises a second module configured to transmit a request to the subscriber database of the mobile communications network requesting the subscriber database to use the location information for all subscribers requesting the use of said one type of service. 
     The control entity can influence the selection of a data path between the user entity and the service instance so that the shortest possible path between the user entity and the service instance is selected as information is provided which allows selecting an access point which is close to the service instance and the user requesting the service. The information about the nearest access point to the mobile communications network is transmitted to the exposure entity, which itself can then inform the subscriber database to use this information for user entities requesting the corresponding type of service. 
     In addition, a system comprising the control entity as discussed above or as discussed below is provided and the exposure entity as discussed above or as discussed below. 
     Furthermore, a computer program comprising program code to be executed by at least one processing unit of the control entity or of the exposure entity is provided, wherein execution of the program code causes the at least one processing unit to execute a method as discussed above or as discussed in further detail below. 
     It is to be understood that the features mentioned above and features yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation without departing from the scope of the present invention. Features of the above-mentioned aspects and embodiments described below may be combined with each other in other embodiments unless explicitly mentioned otherwise. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and additional features and effects of the application will become apparent from the following detailed description when read in conjunction with the accompanying drawings in which like reference numerals refer to like elements. 
         FIG. 1  shows a schematic architectural review of the system in which a client, for accessing a service instance provided by a server is discovering the architecture of the network in order to connect to one of several service instances. 
         FIG. 2  is a schematic view of the system of  FIG. 1  when a traffic from a client to service instance is routed to the closest service instance using an anycast mechanism. 
         FIG. 3  shows a schematic view of the situation shown in  FIG. 2  in which a link failure leads to the routing of the traffic to another service instance providing the same type of service. 
         FIG. 4  shows a schematic architectural review of the system including a control entity configured to influence the selection of the service instance from a plurality of service instances provided in a distributed cloud system. 
         FIG. 5  shows a schematic architectural review of a system in which the traffic of a user entity is directed to the closest access point based on information received from the control entity shown in  FIG. 4 . 
         FIG. 6  shows a schematic message exchange between the entities involved for selecting the closest access point for the traffic in a system of  FIG. 5 . 
         FIG. 7  shows a schematic view of a flowchart comprising the steps that are carried out at the control entity for influencing the selection of the nearest access point to the mobile communications network. 
         FIG. 8  shows a schematic view of a flowchart comprising the steps carried out at an exposure entity which is operated such that the closest access point is selected. 
         FIG. 9  shows an example schematic representation of a control entity as shown in  FIGS. 4 and 5  configured to influence the selection of a service instance from a plurality of service instances which is located close to the user entity. 
         FIG. 10  shows another schematic representation of the control entity of  FIG. 9  configured to influence the selection of the service instance from several service instances. 
         FIG. 11  shows an example schematic representation of an exposure entity configured to receive the location information with the nearest access point from the control entity and configured to forward the location information to the subscriber database. 
         FIG. 12  shows another example schematic representation of the exposure entity configured to receive the location information with the nearest access point from the control entity and configured to forward the location information to the subscriber database. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings. It is to be understood that the following description of embodiments is not to be taken in a limiting sense. The scope of the invention is not intended to be limited by the embodiments described hereinafter or by the drawings, which are to be illustrative only. 
     The drawings are to be regarded as being schematic representations, and elements illustrated in the drawings are not necessarily shown to scale. Rather, the various elements are represented such that their function and general purpose becomes apparent to a person skilled in the art. Any connection or coupling between functional blocks, devices, components of physical or functional units shown in the drawings and described hereinafter may also be implemented by an indirect connection or coupling. A coupling between components may be established over a wired or wireless connection. Functional blocks may be implemented in hardware, software, firmware, or a combination thereof. 
     Within the context of the present application, the term “mobile entity” or “user equipment” (UE) refers to a device for instance used by a person (i.e. a user) for his or her personal communication. It can be a telephone type of device, for example a telephone or a Session Initiating Protocol (SIP) or Voice over IP (VoIP) phone, cellular telephone, a mobile station, cordless phone, or a personal digital assistant type of device like laptop, notebook, notepad, tablet equipped with a wireless data connection. The UE may also be associated with non-humans like animals, plants, or machines. A UE may be equipped with a SIM (Subscriber Identity Module) or electronic-SIM comprising unique identities such as IMSI (International Mobile Subscriber Identity), TMSI (Temporary Mobile Subscriber Identity), or GUTI (Globally Unique Temporary UE Identity) associated with the user using the UE. The presence of a SIM within a UE customizes the UE uniquely with a subscription of the user. 
     For the sake of clarity, it is noted that there is a difference but also a tight connection between a user and a subscriber. A user gets access to a network by acquiring a subscription to the network and by that becomes a subscriber within the network. The network then recognizes the subscriber (e.g. by IMSI, TMSI or GUTI or the like) and uses the associated subscription to identify related subscriber data. A user is the actual user of the UE, and the user may also be the one owning the subscription, but the user and the owner of the subscription may also be different. E.g. the subscription owner may be the parent, and the actual user of the UE could be a child of that parent. 
     As will be described below, the application provides a control entity between a cloud orchestration system and a mobile packet core of a mobile communications network that influences a node selection and a packet core such, that a carrier for a data packet flow, by way of example a GTP tunnel termination or the terminations are placed near application server instance locations in the distributed cloud system. By doing so, the present application removes the disadvantage of anycast routing such that stateful sessions are not broken when topology changes occur in the IP network. This enables network operators to use anycast routing as an elegant solution that ensures traffic locality in distributed cloud systems. Furthermore, application developers are given full flexibility through existing cloud orchestration Application Programming Interfaces, APIs, to place their workloads where they want and steer traffic to the instance closest to the UE without having to deal with the complexity of the mobile communications network. 
     The concept described above as all described in further detail below, can be used together with any kind of mobile communications network, be it a 3G, 4G or 5G network. 
       FIG. 1  shows a schematic architectural view in which different clients, by way of example user entities  10  or  11  want to use a type of service provided by different service instances  31  or  32 . In the network different routers or routing entities  21 - 24  connect the service instances  31  and  32  to the client devices or user entities  10 ,  11 . 
     In connection with  FIG. 2  a situation of an anycast message is shown wherein both service instances  31 ,  32  have the same IP address as indicated in the figure. When the client  10  wants to connect one of the service instances in the network through the routers  21 - 24  it is made sure that the closest service instance, here service instance  31 , is selected as shown by the data packet flow  18 . 
     In  FIG. 3  it is shown that a link failure can occur between router  21  and  23 . As a consequence, the routing changes in the network and for the anycast traffic user data plane  19  is transmitted through routers  22  and  24  to service instance  32 . However, for long living sessions this service instance lacks the application state for ongoing data packet session. This leads to a failure of the data packet session as indicated. 
     As shown in  FIG. 4  a control entity  100  is provided between a cloud orchestration system where the Application Programming Interface (API)  40  and the application developer  50  are shown schematically. The cloud orchestration system can be a container orchestration system which allows application developers to create Application Programming Interfaces objects of type “Service” or “Ingress” to act as a façade for the actual service implementations inside pots or containers. The container implementations are called Endpoints when used in combination with services. Labels and other mechanisms such as custom schedulers can be used by application developers to control the placement of service instances in a distributed cloud environment. The client devices or user entities use services to discover and address server implementations. As the cloud orchestration system such as Kubernetes does not provide software realizations for services of type load balancer and for ingresses, it is up to the cloud provider to implement these. The present application proposes the control entity  100  that makes it feasible to implement load balances and ingresses using anycast IP addresses. This means that the same IP address is assigned to multiple service instances and the selection of the closest instance is simply done by IP routing algorithms like shortest path first, SPF. The network itself becomes the distributed load balancer. By using GTP (GPRS tunneling protocol) tunnels of the mobile communications network to steer application traffic to points near the service implementation, the risk of state loss in case of a network topology change is minimized. 
     The control entity  100  is provided that watches the creation of service endpoints or service instances in the cloud environment, such as the container orchestration system. The control entity  100  then interacts with the packet core  90  shown in  FIG. 4  and transmits information about the location where the service instance has been placed. This has the advantage that application developers are free to influence the placement of the service instances without having to be aware of the underlying traffic steering in the mobile communications network. The packet core  90 , based on the transmitted location information comprising for each service instance the corresponding nearest access point to the mobile communications network, triggers the selection of a user plane function such that the user plane flow, e.g. the GTP tunnel termination is placed close to the application service instance. Accordingly, the present application ensures traffic locality by using existing mechanisms in mobile networks to steer traffic to the location of the application servers. The present idea also reduces or completely removes the risk of anycast rerouting the different application service instances lacking the application state, as was described above as one of the main disadvantages of anycast routing solutions. By way of example, placing the GTP tunnel termination to the same local network, LAN, where the endpoint resides, the risk of traffic rerouting to a remote server instance due to a link failure can be eliminated. 
     As shown in  FIG. 4 , the closest access point can also depend on the user entity requesting the service. To this end the database  130 , as shown comprises the parameter of the quality level, which provides information about an importance of a subscriber. By way of example, the nearest access point selected for a more important user (golden in  FIG. 4 ) may be different to an access point for a less important user which, when they are located in the same place are directed to different access points. The more important user could use the service provided by the edge cloud, whereas the other user may be able to use the service on a another quality level, e.g. a service instance provided in a national or central part of the distributed cloud system. 
     When the control entity  100  monitors the creation of a new service instance and the cloud system informs the control entity  100  that a new service instance is created, the control entity  100  matches the service identifier received from the cloud system and the endpoint IP addresses received from the cloud system, e.g. the cloud container orchestration system against a data base  130  as shown in  FIG. 4  in order to determine the closest mobile network access point for the compute node running the service instance, which can be a server implementation, by way of example a virtual machine or a container. 
     As shown in  FIG. 4 , the database comprises for each type of service the service endpoint and the closest access point to the mobile communications network. 
     A DNS resolution of FQDN (Fully Qualified Domain Name) can be used in addition and is compatible with the approach, but is not required for the solution. It is an advantage of anycast routing that it can also work with clients that use server IP addresses directly. 
     The invention can use a common way of describing network locations and this common understanding of locations is established between the distributed cloud system, the cloud orchestration system, the packet core  90  and the control entity  100 . By way of example, the geographical coordinates such as latitude and longitude can be used to determine the distance between the network elements. In another example, the metrices of the routing protocols are used to determine the distance between network elements. As another option latency measurements can be used to determine the distance between network elements. The location information is attached to the compute nodes so that it can be referred to when placing the IT application workloads as well as when instantiating or referring to existing packet core node functions. 
     In 3G and 4G EPC (Enhanced Packet Core) the control entity  100  steers the selection of GGSN or P-GW to influence GTP tunnel termination to occur near the application server instance. With Control Plane User Plane Split (CUPS) present in Packet Core, the control entity influences the selection of PGW-U user plane nodes. In 5G core the control entity influences the selection of UPF (user plane functions). 
     In one example, the control entity  100  uses the APN (Access Point Name) override feature in the 4G packet core to influence the point of local break-out. This approach establishes a large number of APNs, one per each distributed cloud location. The packet core then overrides the Access Point Name (APN) selected by the UE in such a way that GTP tunnel termination is placed near the application workload. This approach allows to control place of local break-out with minimal or no impact on existing packet core software implementations. 
     In one example, where CUPS is used in 4G core, a virtual APN (vAPN) is used to apply the APN override feature for selection of user plane devices (GW-U). 
     The Service Capability Exposure Function (SCEF) can be extended with functionality to influence the location of local break-out and the controller device interacts with the SCEF. 
     The control entity  100  uses the Network Exposure Function (NEF) in a 5G Core (5GC) Service Based Architecture (SBA) network to influence the location of local break-out. 
       FIG. 5  gives an example how user data of data packet flow between the user entity  60  and the service instance  31  are routed taking into account location information provided by the control entity  100 . As discussed above in connection with  FIG. 4 , the control entity  100  collects the information about the location of the different service instances provided by the distributed cloud system  30 . This location information indicating for each service instance the corresponding nearest access point to the mobile communications network is transmitted to the packet core  90  as shown by the dashed line  25  of the control signaling. As will be described in further detail below, the information is used in the packet core network by entities such as the exposure entity and the subscriber database so that the access point transmitted from the subscriber database is used for setting up a GTP tunnel  26  as shown in  FIG. 5  in which the user plane data traffic is routed from the user entity  60  to a user plane function or user plane gateway  70  which is located close to the service instance  31 . The end user application traffic is indicated by the dashed line  27 . The user of the user entity  60  is directed to the service instance as shown, another user located in the same location as user entity may be directed to another part of the distributed cloud system (not shown in  FIG. 5 ) located closer or further away than service instance  31  in dependence of the subscription the user has. Subscriber with a higher value of importance may be directed to a closer service instance compared to subscriber having a lower value of importance. 
     In the following, a possible implementation is discussed in connection with a 4G mobile core network.
     1. An interface, e.g. the northbound T8 interface of the SCEF (Service Capability Exposure Function) is extended with a new API to influence the placement of GTP tunnel termination for individual subscribers or classes of subscribers.   2. The control entity  100  subscribes for (watches) the creation of services and corresponding endpoints (server implementations) in the cloud orchestration system (e.g. Kubernetes).   3. The cloud orchestration system notifies the control entity  100  of creation of new service Endpoints.   4. The control entity  100  holds information linking service endpoints in the cloud container orchestration system with APNs in the mobile network. The control entity  100  matches the service identifier and endpoint IP addresses received from the cloud container orchestration system against the database  130  to determine the closest mobile network access point for the compute node running the service endpoint (server implementation, i.e. VM, Virtual Machine, or container).   5. When the control entity  100  receives notification of the creation of a service endpoint that it has knowledge of and that is registered for traffic optimization, it initiates the following procedure:   6. The control entity  100  through the extended T8 interface sends an influence request to the SCEF including a service identifier and an access point name (APN).   7. A functionality provided in the SCEF sends a request to the HSS, e.g. through the S 6   t  interface to configure the APN override feature for all subscribers marked with the service tag, i.e. requesting this service, derived from the aforementioned database. The functionality in the SCEF can also only configure the APN override feature for the users which are tagged with that label as well, thus in dependence on their subscription. Through this a subset of users which are marked with the service tag can use the service on the Edge-Cloud. Other users would then be configured with another APN override so that they are able to use the service but on another quality level (National/Central-Cloud). So in the aforementioned database we would have more rows not only showing the Closest APN but different APNs which stand for different quality levels.   

     The following procedure is triggered by subscriber activity (e.g. attach or mobility):
     a) The MME (Mobile Management Entity) sends update location request to HSS upon which the HSS responds with update location answer containing the subscriber profile and the APN previously stored with the subscriber profile.   b) MME selects an S-GW and a P-GW based on received APN and geographical closeness to the tracking area of the subscriber. MME sends a create session request message to S-GW containing among other data the APN, P-GW IP address, and subscriber profile. The S-GW establishes GTP tunnel between S-GW and the P-GW holding the APN and GTP termination point designated by the control entity  100  in the previous procedure.   

     For already existing EPS sessions, a forced EPS session termination is used to make APN change take effect. 
     In the examples above the invention was discussed in connection with a GTP tunnel scheme. However it should be understood that the invention is limited to this scheme. As an alternative PMIP (Proxy Mobile IP) could be used which is being used for CDMA (Code Division Multiple Access) and WIMAX. PMIP (Proxy Mobile IPv6) is a protocol used to create connectivity between an LMA (Local Mobility Anchor) and a MAG (Mobility Access Gateway). PMIP uses GRE (Generic Routing Encapsulation) tunnels. The invention discussed above with the nearest access points can also be applied in this technology. 
     In another example, the control entity  100  takes into consideration the capacity of server implementations in each site and only directs a limited number of EPS sessions to each site based on the available capacity. 
       FIG. 6  summarizes some of the steps exchanged between the different entities discussed above. In step S 10  the control entity  100  transmits a subscribe service/endpoint creation message to the cloud orchestrator  35  which notifies the control entity  100  of the creation of a new service instance in step S 11 . In step S 12  the control entity checks whether the endpoint matches the service to be optimized. If this is the case, in step S 13  the control entity looks up the closest access point name for the endpoint node from the database  130  and transmits in step S 14  an influence request indicating the type of service and the access point name to the exposure entity  200 . In step S 15  the exposure entity  200  transmits an override request requesting to override the access point name for the subscribers for the indicated service to the subscriber database  92 . In step S 16  the subscriber database updates the subscriber profiles. In step S 17  a subscriber attaches to the network or a mobility of the subscriber changes and the use of a service is requested by the user device. In step S 18  an update location request is sent to the subscriber database and in step S 19  the answer is transmitted back to the MME. In step S 20  the MME selects a packet gateway and a serving gateway and transmits a create session request to the serving gateway which is forwarded to the packet gateway in step S 22 . In step S 23  the GTP tunnel is finally established with the wanted termination point. 
       FIG. 7  summarizes some of the main steps carried out at the control entity. In step S 31  the control entity monitors the creation of new service instances for a defined type of service in the distributed cloud system. For each new service instance the corresponding location in the distributed cloud system is determined and in step S 32  location information is determined which indicates for each service instance the location and the corresponding nearest access point to the mobile communications network. As discussed above in connection with  FIGS. 4 / 5  the location information is determined based on the information provided in the database  130 . In step S 33  the location information is then transmitted to the mobile communications network and the network is requested to take into account the transmitted location information for selection of the user plane entity which is configured to transmit the user plane of the data packet flow between the user entity and one of the service instances. 
     As discussed above, the location information can be transmitted to the exposure entity. However, it should be understood that it may be transmitted to any other entity of the mobile communications network. 
     As far as the exposure entity is concerned,  FIG. 8  shows some of the main steps carried out at the exposure entity  200 . In step S 41  the exposure entity receives the request from the control entity  100  wherein the request comprises the location information indicating for the service instance the corresponding nearest access point to the mobile communications network. Furthermore, in step S 42  a request is transmitted to a subscriber database  92  of the mobile communications network, wherein the subscriber database is requested to use the location information for all subscribers requesting the use of said one type of service. The request is transmitted in response to the received request in S 31 . 
       FIG. 9  shows a schematic architectural view of the control entity  100  which can carry out the above discussed influencing of the selection of the service instance. The control entity  100  comprises an interface or input/output  110  which is provided for transmitting user data or control messages to other entities and which is configured to receive user data or control messages from other entities. By way of example, the interface  110  is configured to receive the information from the distributed cloud system about the new service instances and the location in the network. The interface is furthermore configured to transmit the location information to the core network as discussed above. The control entity  100  furthermore comprises a processing unit  120  which is responsible for the operation of the control entity  100  as discussed above. The processing unit  120  comprises one or more processors and can carry out instructions stored on a memory  130 , wherein the memory may include read-only memory, a random access memory, a mass storage, a hard disk or the like. The memory can furthermore include suitable program code to be executed by the processing unit  120  so as to implement the above described functionalities in which the control entity  100  is involved. 
       FIG. 10  shows another architectural view of such a control entity, here entity  300  which comprises a first module  310  configured to monitor the creation of the new service instances. As described above, the first module may subscribe for the creation of the service instances in the cloud orchestration system. A second module  320  is provided for determining the location information comprising the nearest access point for each service instance in the mobile communications network. A third module  330  is provided for transmitting the location information to the core network. 
       FIG. 11  shows a schematic architectural view of the exposure entity  200 , wherein the entity  200  comprises an interface or input/output  210  provided for transmitting user data or control messages and configured to receive user data or control messages from other entities. The interface  210  can receive the information from the control entity  100  comprising the location information and can forward it to the subscriber database as discussed above. The exposure entity  200  can furthermore comprise a processing unit  220  which is responsible for the operation of the entity  200 . The processing unit  220  can comprise one or more processors and can carry out instructions stored on a memory  230 , wherein the memory can include a read-only memory, a random access memory, a mass storage, a hard disc or the like. The memory  230  can furthermore include suitable program code to be executed by the processing unit  220  so as to implement the above described functionalities in which the exposure entity is involved. 
       FIG. 12  shows another architectural view of an exposure entity  400  comprising a first module  410  configured to receive the request from the control entity the request comprising the location information with the nearest access point. The exposure entity furthermore transmits the request to the subscriber database and requests the subscriber database to use the location information for all subscribers requesting the corresponding type of service using a second module  420 . From the above said some general conclusions can be drawn. By way of example, for the control entity which monitors the creation of new service instances, the creation of all new service instances providing different types of services can be monitored wherein the location information is determined by the control entity and transmitted for each service instance and for each type of the different types of services to the mobile communications network. 
     In order to monitor the creation of the new service instances, the control entity may transmit a request to the distributed cloud system requesting that the control entity be informed each time a new service instance is created in the distributed cloud system. Furthermore, a response is received to the transmitted request wherein the response comprises the new service instance and its location in the distributed cloud system. 
     When the location information is transmitted to the mobile communications network, it may be transmitted to the exposure entity  200  configured to expose the services provided by the mobile communications network or accessible through the mobile communications network. 
     When the location information is transmitted to the network, an influence request can be transmitted to the exposure entity  200 , wherein the request comprises the service identifier identifying the service and an access identifier identifying the nearest access point. 
     When a response in response to the transmitted request is received from the distributed cloud system, it is checked whether the new service instance is provided for a service requiring traffic optimization. The location information is only transmitted to the mobile communications network when it is confirmed that the new service instance is provided for a service requiring traffic optimization. 
     The nearest access point in the location information may be determined based on the nearest access point using the geographical coordinates of the access point and the service instance, using the metrics of a routing protocol used to route the user data plane between the service instance and the access point or based on latency measurements carried out on the user data plane. 
     Furthermore, it is possible that the processing capacity of each new service instance is determined and the location information within the nearest access point is determined taking into account the processing capacity of each new service instance such that the nearest access point for one service instance additionally depends on the processing capacity of the service instance. By way of example, when the processing capacity of a service instance is smaller compared to the processing capacity of another service instance located in the neighborhood, a smaller amount of data packet sessions may be directed to the service instance with the lower processing capacity It is assumed that in anycast addressing, routing in the network makes sure packets from an end device are routed to the service instance closest to the tunnel termination point. Thus by selecting a termination point for a certain number of session, it is possible to control the number of session that send traffic to a given service instance. 
     For determining the nearest access point the control entity can access a database where the nearest access point is stored for the each service instance. 
     The selection of the nearest access point can also depend on the mobile device/subscription of the user of the mobile device. For different subscribers different nearest access points can be stored in the database in order to be able to differentiate different subscriber levels. 
     As far as the exposure entity is concerned, when the exposure entity transmits the request to a subscriber database, the transmitted request can be an override request requesting to override the available access information in the subscriber database for the service instances providing said one type of service with the location information present in the request for all subscribers requesting said one type of service wherein the access information provides information where the mobile communications network connects to a packet switched wide area network such as the internet. 
     The above described application has the advantage that the IT application developers can control the placement of their workloads in the distributed cloud and keep the traffic local without the knowledge of the packet cores. Furthermore, the mobile communications network, e.g. the packet core, can dynamically steer the application traffic to geographically closest application service instances while avoiding disadvantages inherent to known solutions. Furthermore, the invention enables synergies between the packet core and the distributed cloud.