Title

Coordination of segmented service chains

Field

Various example embodiments relate to coordination of segmented service chains. More specifically, various example embodiments exemplarily relate to measures (including methods, apparatuses and computer program products) for realizing coordination of segmented service chains.

Background

The present specification generally relates to service function chain where multiple composite micro service functions are traversed in a specific order to implement the complete service.

Large services are typically decomposed into sub-services. In the trending micro service architecture, end-to-end services/applications are made up of a collection of loosely coupled services, called micro services. Such micro services can be connected by a service function chain where multiple composite micro service functions are traversed in a specific order to implement the complete service.

Examples of such micro services (or component services) are encoding/decoding of an encrypted stream, caching frequently used content or request-responses, WAN acceleration, server load balancing, hierarchical content caching, augmented reality (AR)/ virtual reality (VR) where local information is overlaid on top base image from the centralized server, etc.

An architecture for service chaining is provided in Internet Engineering Task Force (IETF) RFC 7665 "Architecture for Service Function Chains" (SFC). Protocol mechanisms for service function chaining is provided in IETF RFC 8300 "Network Service Header" (NSH).

Third Generation Partnership Project (3GPP) has previously done a normative work called "Flexible Mobile Service Steering (FMSS) for Release 13 (Long Term Evolution (LTE))" for 4G networks (which has followed a study documented in 3GPP TR22.808). Support of mobile service steering has been specified in the first release (R-15) of 5G.

The current service chain model applied in 3GPP networks including 5G core network (5GC) is based on the FMSS concept (thus based on evolved packet core (EPC) architecture), and considers N6-LAN as being outside of the 3GPP scope.

However, 5GC has introduced some new powerful features to support traffic routing to edge clouds whose interaction with service flow chaining (SFC)/mobile service steering has not been studied. Examples of such features to support traffic routing to edge clouds are uplink classifier (UL CL), branching point (BP), powerful forwarding and detection rules to support multiple N 6- interfaces, and local break out, etc.

Introduction of core and edge services may facilitate the execution of services in stages where one part of the services is in the edge and other part is in the core network. Time critical or location context relevant parts of a service might be executed in the edge, while parts that require network wide or global context might be executed in the core.

A key issue of enhancement of support for edge computing in 5GC (Release 17) considered the interactions between SFC and mobile service (steering) but work was stalled due to lack of time.

Here, in relation to consecutive traffic steering in different N6-LANs, how the 5GC is made aware that (uplink/downlink (UL/DL)) application traffic needs to be processed via the local (i.e., edge-side) N6-LAN and /or the central N6- LAN and how to provide the 5GC with information about service functions in N6-LAN (both local and central) that application traffic needs to travel through, e.g. service function order and location, may become relevant.

3GPP TS 23.503 (R-16) defines policy and charging control (PCC) rule information in 5GC, which according to the following table (Table 6.3.1) contains: According to NOTE 18, only one of the two shall be present in a PCC rule.

Further, according to NOTE 19, per DNAI, a traffic steering policy identifier and/or N6 traffic routing information can be provided. If the pre-configured traffic steering policy (that is referenced by the traffic steering policy identifier) contains information that is overlapping with the N6 traffic routing information, the N6 traffic routing information shall take precedence.

As mentioned above, due to the adoption of micro services in service creation and deployment, end-to-end services are executed as a chain of smaller services or component services that are progressed in stages.

This type of service execution is also known as service function chaining (RFC 7665). Particularly, in 5G, there could be multiple N6-interfaces and routes to the data network(s) (DN) hosting the services and their composite service functions. N6 is the name of the interface or reference point between a user plane function (UPF) and a data network. Multiple N6-interfaces and routes to the data network(s) are e.g. defined in TS23.501, section 5.6.4. Some of N6 interfaces may be located at the edge close to the UE, while some of N6 interfaces may be centrally located at the core network.

Currently, a packet data unit (PDU) session is between a terminal such as a user equipment (UE) and the local break out N6 (edge service accessed by the local N6-LAN), and/or between the UE and the central N6 (central application service).

However, there is no means to distribute the service chain between edge part and central part even if this would benefit the service quality of experience (QoE) substantially by allocating time critical components to the edge and those components with wider context of service into the core network. It is not possible to process packets of a flow first in the service chain located in the edge and then forward the packet to the core resident service chain or the other way round, i.e. process the packets first in the service chain of the core and then in the service chain of the edge before send the packets to the UE.

Hence, the problem arises that distribution of a service chain between edge part and central part is not provided, and a management and coordination thereof is not foreseen. Accordingly, potential service quality improvements cannot be provided.

Hence, there is a need to provide for coordination of segmented service chains.

Various example embodiments aim at addressing at least part of the above issues and/or problems and drawbacks.

Various aspects of example embodiments are set out in the appended claims.

According to an exemplary aspect, there is provided a method comprising transmitting policy charging control rule information towards a session management function entity, wherein said policy charging control rule information is indicative of a segmented service function chain, and said segmented service function chain is segmented into a first segment and a second segment.

According to an exemplary aspect, there is provided a method comprising receiving policy charging control rule information from a policy control function entity, wherein said policy charging control rule information is indicative of a segmented service function chain, and said segmented service function chain is segmented into a first segment and a second segment. According to an exemplary aspect, there is provided a method of a user plane function entity interfacing with application services of a segment of a segmented service function chain, the method comprising receiving, from a session management function entity, mappings between uplink/downlink packet detection rule information and a forwarding rule information containing a service function chain identifier.

According to an exemplary aspect, there is provided a method of a user plane function entity, the method comprising receiving, from a session management function entity, uplink/downlink packet detection rule information indicative of forwarding between an interface towards core network based application services and an interface towards network edge based application services.

According to an exemplary aspect, there is provided a method of a user plane function entity, the method comprising receiving, from said session management function entity, forwarding rule information to be used for forwarding between an interface towards core network based application services and an interface towards network edge based application services.

According to an exemplary aspect, there is provided an apparatus comprising transmitting circuitry configured to transmit policy charging control rule information towards a session management function entity, wherein said policy charging control rule information is indicative of a segmented service function chain, and said segmented service function chain is segmented into a first segment and a second segment.

According to an exemplary aspect, there is provided an apparatus comprising receiving circuitry configured to receive policy charging control rule information from a policy control function entity, wherein said policy charging control rule information is indicative of a segmented service function chain, and said segmented service function chain is segmented into a first segment and a second segment. According to an exemplary aspect, there is provided an apparatus of a user plane function entity interfacing with application services of a segment of a segmented service function chain, the apparatus comprising receiving circuitry configured to receive, from a session management function entity, mappings between uplink/downlink packet detection rule information and a forwarding rule information containing a service function chain identifier.

According to an exemplary aspect, there is provided an apparatus of a user plane function entity, the apparatus comprising receiving circuitry configured to receive, from a session management function entity, uplink/downlink packet detection rule information indicative of forwarding between an interface towards core network based application services and an interface towards network edge based application services.

According to an exemplary aspect, there is provided an apparatus of a user plane function entity, the apparatus comprising receiving circuitry configured to receive, from a session management function entity, forwarding rule information to be used for forwarding between an interface towards core network based application services and an interface towards network edge based application services.

According to an exemplary aspect, there is provided an apparatus comprising at least one processor, at least one memory including computer program code, and at least one interface configured for communication with at least another apparatus, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform transmitting policy charging control rule information towards a session management function entity, wherein said policy charging control rule information is indicative of a segmented service function chain, and said segmented service function chain is segmented into a first segment and a second segment. According to an exemplary aspect, there is provided an apparatus comprising at least one processor, at least one memory including computer program code, and at least one interface configured for communication with at least another apparatus, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform receiving policy charging control rule information from a policy control function entity, wherein said policy charging control rule information is indicative of a segmented service function chain, and said segmented service function chain is segmented into a first segment and a second segment.

According to an exemplary aspect, there is provided an apparatus of a user plane function entity interfacing with application services of a segment of a segmented service function chain, the apparatus comprising at least one processor, at least one memory including computer program code, and at least one interface configured for communication with at least another apparatus, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform receiving, from a session management function entity, mappings between uplink/downlink packet detection rule information and a forwarding rule information containing a service function chain identifier.

According to an exemplary aspect, there is provided an apparatus of a user plane function entity, the apparatus comprising at least one processor, at least one memory including computer program code, and at least one interface configured for communication with at least another apparatus, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform receiving, from a session management function entity, uplink/downlink packet detection rule information indicative of forwarding between an interface towards core network based application services and an interface towards network edge based application services. According to an exemplary aspect, there is provided an apparatus of a user plane function entity, the apparatus comprising at least one processor, at least one memory including computer program code, and at least one interface configured for communication with at least another apparatus, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to perform receiving, from a session management function entity, forwarding rule information to be used for forwarding between an interface towards core network based application services and an interface towards network edge based application services.

According to an exemplary aspect, there is provided a computer program product comprising computer-executable computer program code which, when the program is run on a computer (e.g. a computer of an apparatus according to any one of the aforementioned apparatus-related exemplary aspects of the present disclosure), is configured to cause the computer to carry out the method according to any one of the aforementioned method- related exemplary aspects of the present disclosure.

Such computer program product may comprise (or be embodied) a (tangible) computer-readable (storage) medium or the like on which the computer- executable computer program code is stored, and/or the program may be directly loadable into an internal memory of the computer or a processor thereof.

Any one of the above aspects enables an efficient control and management of separated service chains, thereby enabling an improvement of service quality by exploiting respective advantages of respective service segment locations, to thereby solve at least part of the problems and drawbacks identified in relation to the prior art.

By way of example embodiments, there is provided coordination of segmented service chains. More specifically, by way of example embodiments, there are provided measures and mechanisms for realizing coordination of segmented service chains.

Thus, improvement is achieved by methods, apparatuses and computer program products enabling/realizing coordination of segmented service chains.

Brief description of the drawings

In the following, the present disclosure will be described in greater detail by way of non-limiting examples with reference to the accompanying drawings, in which

Figure 1 is a block diagram illustrating an apparatus according to example embodiments,

Figure 2 is a block diagram illustrating an apparatus according to example embodiments,

Figure 3 is a block diagram illustrating an apparatus according to example embodiments,

Figure 4 is a block diagram illustrating an apparatus according to example embodiments,

Figure 5 is a block diagram illustrating an apparatus according to example embodiments,

Figure 6 is a block diagram illustrating an apparatus according to example embodiments,

Figure 7 is a schematic diagram of a procedure according to example embodiments, Figure 8 is a schematic diagram of a procedure according to example embodiments,

Figure 9 is a schematic diagram of a procedure according to example embodiments,

Figure 10 shows a schematic diagram of an example of a system environment with signaling variants according to example embodiments,

Figure 11 shows a schematic diagram of an example of a system environment with interfaces between network entities according to example embodiments,

Figure 12 shows a schematic diagram of signaling sequences according to example embodiments, and

Figure 13 is a block diagram alternatively illustrating apparatuses according to example embodiments.

Detailed description

The present disclosure is described herein with reference to particular non limiting examples and to what are presently considered to be conceivable embodiments. A person skilled in the art will appreciate that the disclosure is by no means limited to these examples, and may be more broadly applied.

It is to be noted that the following description of the present disclosure and its embodiments mainly refers to specifications being used as non-limiting examples for certain exemplary network configurations and deployments. Namely, the present disclosure and its embodiments are mainly described in relation to 3GPP specifications being used as non-limiting examples for certain exemplary network configurations and deployments. As such, the description of example embodiments given herein specifically refers to terminology which is directly related thereto. Such terminology is only used in the context of the presented non-limiting examples, and does naturally not limit the disclosure in any way. Rather, any other communication or communication related system deployment, etc. may also be utilized as long as compliant with the features described herein.

Hereinafter, various embodiments and implementations of the present disclosure and its aspects or embodiments are described using several variants and/or alternatives. It is generally noted that, according to certain needs and constraints, all of the described variants and/or alternatives may be provided alone or in any conceivable combination (also including combinations of individual features of the various variants and/or alternatives).

According to example embodiments, in general terms, there are provided measures and mechanisms for (enabling/realizing) coordination of segmented service chains.

In brief, according to example embodiments, among others, mechanisms and related traffic forwarding rules for 5G UPFs to forward packets of a data flow selectively back to UE or to further processing at the service chain segment either in the core or in the edge depending on where the service chaining continues are defined.

Figure 10 shows a schematic diagram of an example of a system environment with signaling variants according to example embodiments. In particular, Figure 10 illustrates concatenating a service flow processing in the edge and in the core according to example embodiments compared to service flow processing only in the edge or only in the core.

The system environment illustrates a radio access network (RAN) (to which a terminal, e.g. a UE, is connected), a UPF associated with Edge Application Services (linked via a local N6 interface) and linked with the RAN via an N3 interface, a UPF associated with Central Application Services (linked via a central N6 interface) and linked with the former UPF via an N9 interface. It has to be noted that this is just a non-limiting example of network deployment utilized for explanations in the present specification. However, for example the RAN could be replaced by any 5G Access Network (such as a W-AGF for Wireline access, N3IWF for untrusted Non 3GPP access, etc.). Likewise, example embodiments cover also cases where multiple UPF(s) are used, while Figure 10 only shows a single UPF.

In more detail, with a solid curve, a case is shown in which a service chain is split between the edge (SFC part A) and the core (SFC part B).The solid curve shows the intended service data flow.

Further, with a broken curve, a case is shown in which a service chain is supported exclusively by the edge (SFC part A). The broken curve shows the intended service data flow.

Furthermore, with a dotted curve, a case is shown in which a service chain is supported exclusively by the core (SFC part B). The dotted curve shows the intended service data flow.

According to example embodiments, among others, mechanisms and related traffic forwarding rules for 5G UPFs to forward packets of a data flow according to the respective intended service data flows are provided.

In more detail, according to example embodiments, new PCC rules for a session management function (SMF) and a UPF to steer traffic between the edge cloud resident SFC-segment and the central cloud resident SFC- segment are defined so that a correct GTP-U tunnel can be identified with an embedded terminal identifier (e.g. UE IP address). Here, according to example embodiments, importance is attached to traffic steering between the concatenated SFC-segments (e.g. SFC part A and SFC B in Figure 10).

At this point, according to example embodiments, the UPF decides if the packet of a flow needs to be forwarded to the next SFC-segment (e.g. SFC- segment part B in Figure 10) or sent back to the UE.

For this purpose, according to example embodiments, the UPF learns via PDR (and FAR) whether the UL traffic from the local SFC environment needs to be forwarded to the next SFC-segment (e.g. SFC-segment part B in Figure 10) or sent back to the UE.

According to example embodiments (e.g. to support the case where the UL traffic from the local SFC environment needs to be forwarded to the next SFC- segment), a novel PDR rule is defined for the egress UPF (acting as an auxiliary service function forwarder SFF) to look for the UE IP address, or in general, for the UE ID (as an example for the terminal identifier) inside the encapsulated data packet, i.e., for the source address of an inner IP packet, or to look for the UE ID from a NSH header metadata or from being embedded into an SFC ID. Then an already defined FAR can forward the traffic to the next SFC-segment.

According to further example embodiments, related policy rules in a policy control function (PCF) and the associated packet detection rules (PDR) and forwarding rules (FAR) that are communicated by the SMF to the UPF are extended to steer the flow of packets accordingly between the segments of the SFC.

In the following, example embodiments are explained in other words.

Figure 1 is a block diagram illustrating an apparatus according to example embodiments. The apparatus may be a network entity 10 such as a policy control function entity comprising a transmitting circuitry 11. The transmitting circuitry 11 transmits policy charging control rule information towards a session management function entity. The policy charging control rule information is indicative of a segmented service function chain. Further, the segmented service function chain is segmented into a first segment and a second segment. Figure 7 is a schematic diagram of a procedure according to example embodiments. The apparatus according to Figure 1 may perform the method of Figure 7 but is not limited to this method. The method of Figure 7 may be performed by the apparatus of Figure 1 but is not limited to being performed by this apparatus.

As shown in Figure 7, a procedure according to example embodiments comprises an operation of transmitting (S71) policy charging control rule information towards a session management function entity. The policy charging control rule information is indicative of a segmented service function chain. Further, the segmented service function chain is segmented into a first segment and a second segment.

Figure 2 is a block diagram illustrating an apparatus according to example embodiments. In particular, Figure 2 illustrates a variation of the apparatus shown in Figure 1. The apparatus according to Figure 2 may thus further comprise a grouping circuitry 21.

In an embodiment at least some of the functionalities of the apparatus shown in Figure 1 (or 2) may be shared between two physically separate devices forming one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes.

According to further example embodiments, said first segment is any one of a service function chain segment of core network based application services and a service function chain segment of network edge based application services. In addition, according to further example embodiments, said second segment is the other one of said service function chain segment of core network based application services and said service function chain segment of network edge based application services.

According to further example embodiments, said policy charging control rule information is indicative of a segmented service function chain.

According to further example embodiments, said policy charging control rule information includes a traffic steering policy identifier referencing a pre configured traffic steering policy at an interface towards said network edge based application services.

Alternatively, or in addition, according to further example embodiments, said policy charging control rule information includes traffic routing information related to traffic routing at said interface towards said network edge based application services.

In addition, according to further example embodiments, said policy charging control rule information contains said indication of a segmented service function chain associated with a traffic offload indication.

According to further example embodiments, said indication of a segmented service function chain is associated with a traffic offload indication.

According to further example embodiments, the policy charging control rule information contains a rule referencing to traffic steering policies to apply when no traffic offload takes place and a rule referencing to other traffic steering policies to apply when traffic offload takes place.

According to further example embodiments, said interface towards said core network based application services is a central N6 interface. According to a variation of the procedure shown in Figure 7, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise an operation of identifying and grouping service function segments into edge segments and core segments to be shared across different end to end services chains and their user as indicated by said policy charging control rule information.

Figure 3 is a block diagram illustrating an apparatus according to example embodiments. The apparatus may be a network entity 30 such as a session management function entity comprising a receiving circuitry 31. The receiving circuitry 31 receives policy charging control rule information from a policy control function entity. The policy charging control rule information is indicative of a segmented service function chain. Further, the segmented service function chain is segmented into a first segment and a second segment. Figure 8 is a schematic diagram of a procedure according to example embodiments. The apparatus according to Figure 3 may perform the method of Figure 8 but is not limited to this method. The method of Figure 8 may be performed by the apparatus of Figure 3 but is not limited to being performed by this apparatus.

As shown in Figure 8, a procedure according to example embodiments comprises an operation of receiving (S81) policy charging control rule information from a policy control function entity. The policy charging control rule information is indicative of a segmented service function chain. Further, the segmented service function chain is segmented into a first segment and a second segment.

Figure 4 is a block diagram illustrating an apparatus according to example embodiments. In particular, Figure 4 illustrates a variation of the apparatus shown in Figure 3. The apparatus according to Figure 4 may thus further comprise a grouping circuitry 41, a selecting circuitry 42, and/or a transmitting circuitry 43.

In an embodiment at least some of the functionalities of the apparatus shown in Figure 3 (or 4) may be shared between two physically separate devices forming one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes.

According to further example embodiments, said first segment is any one of a service function chain segment of core network based application services and a service function chain segment of network edge based application services.

In addition, according to further example embodiments, said second segment is the other one of said service function chain segment of core network based application services and said service function chain segment of network edge based application services.

According to further example embodiments, said policy charging control rule information includes a traffic steering policy identifier referencing a pre configured traffic steering policy at an interface towards said network edge based application services.

Alternatively, or in addition, according to further example embodiments, said policy charging control rule information includes traffic routing information related to traffic routing at said interface towards said network edge based application services.

According to further example embodiments, said indication of a segmented service function chain is associated with a traffic offload indication. According to further example embodiments, the policy charging control rule information contains a rule referencing to traffic steering policies to apply when no traffic offload takes place and a rule referencing to other traffic steering policies to apply when traffic offload takes place.

According to further example embodiments, said interface towards said core network based application services is a central N6 interface.

According to a variation of the procedure shown in Figure 8, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise an operation of identifying and grouping service function segments into edge segments and core segments to be shared across different end to end services chains and their user as indicated by said policy charging control rule information.

According to a variation of the procedure shown in Figure 8, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise an operation of selecting at least one first user plane function entity for application services of said first segment based on said policy charging control rule information, and an operation of selecting at least one second user plane function entity for application services of said second segment based on said policy charging control rule information.

According to a variation of the procedure shown in Figure 8, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise an operation of transmitting, towards any of said at least one first user plane function entity and said at least one second user plane function entity, uplink/downlink packet detection rule information indicative of forwarding between an interface towards core network based application services and an interface towards network edge based application services.

According to a variation of the procedure shown in Figure 8, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise an operation of transmitting, towards any of said at least one first user plane function entity and said at least one second user plane function entity, forwarding rule information to be used for forwarding between an interface towards core network based application services and an interface towards network edge based application services.

According to further example embodiments, said forwarding rule information is indicative of a tunnel towards said one first user plane function entity (i.e., towards one of said at least one first user plane function entity) or a tunnel towards said one second user plane function entity (i.e., towards one of said at least one second user plane function entity), wherein said tunnel towards said one first user plane function entity and said tunnel towards said one second user plane function entity are associated with a data session of a user equipment.

According to a variation of the procedure shown in Figure 8, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise an operation of transmitting, towards any of said at least one first user plane function entity and said at least one second user plane function entity, forwarding rule information containing an explicit service function chain identifier.

Figure 5 is a block diagram illustrating an apparatus according to example embodiments. The apparatus may be a network entity 50 such as a user plane function entity (interfacing with application services of a segment of a segmented service function chain) comprising a receiving circuitry 51. The receiving circuitry 51 receives, from a session management function entity, mappings between uplink/downlink packet detection rule information and a forwarding rule information containing a service function chain identifier. Alternatively, the receiving circuitry 51 receives, from a session management function entity, uplink/downlink packet detection rule information indicative of forwarding between an interface towards core network based application services and an interface towards network edge based application services. Alternatively, the receiving circuitry 51 receives, from a session management function entity, forwarding rule information to be used for forwarding between an interface towards core network based application services and an interface towards network edge based application services. Figure 9 is a schematic diagram of a procedure according to example embodiments. The apparatus according to Figure 5 may perform the method of Figure 9 but is not limited to this method. The method of Figure 9 may be performed by the apparatus of Figure 5 but is not limited to being performed by this apparatus.

As shown in Figure 9, a procedure according to example embodiments comprises an operation of receiving (S91), from a session management function entity, mappings between uplink/downlink packet detection rule information and a forwarding rule information containing a service function chain identifier. Alternatively, a procedure according to example embodiments comprises an operation of receiving (S91), from a session management function entity, uplink/downlink packet detection rule information indicative of forwarding between an interface towards core network based application services and an interface towards network edge based application services. Alternatively, a procedure according to example embodiments comprises an operation of receiving (S91), from a session management function entity, forwarding rule information to be used for forwarding between an interface towards core network based application services and an interface towards network edge based application services.

Figure 6 is a block diagram illustrating an apparatus according to example embodiments. In particular, Figure 6 illustrates a variation of the apparatus shown in Figure 5. The apparatus according to Figure 6 may thus further comprise a matching circuitry 61, an adding circuitry 62, and/or an acting circuitry 63.

In an embodiment at least some of the functionalities of the apparatus shown in Figure 5 (or 6) may be shared between two physically separate devices forming one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes.

According to a variation of the procedure shown in Figure 9, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise an operation of receiving, from said session management function entity, mappings between said uplink/downlink packet detection rule information and a service function chain identifier.

According to a variation of the procedure shown in Figure 9, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise an operation of receiving, from said session management function entity, forwarding rule information to be used for forwarding between an interface towards core network based application services and an interface towards network edge based application services.

According to further example embodiments, said method is a method of a first user plane function entity, and said forwarding rule information is indicative of a tunnel towards a second user plane function entity, wherein said tunnel is associated with a data session of a user equipment.

According to a variation of the procedure shown in Figure 9, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise an operation of receiving a packet of a service data flow, and an operation of matching said packet with said uplink/downlink packet detection rule information. If said packet matches with said uplink/downlink packet detection rule information, such exemplary method according to example embodiments may comprise an operation of adding a service identifier to said packet, and an operation of adding a transport encapsulation to said packet.

According to further example embodiments, said uplink/downlink packet detection rule information is indicative of looking up a user equipment identifier or a user equipment address from an inner packet of a transport encapsulated packet.

Alternatively, or in addition, according to further example embodiments, said uplink/downlink packet detection rule information is indicative of looking up said user equipment identifier or said user equipment address from metadata of a service header.

According to a variation of the procedure shown in Figure 9, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise an operation of receiving a packet of a service data flow from an interface towards core network based application services or an interface towards network edge based application services, and an operation of matching said packet with said uplink/downlink packet detection rule information. If said packet matches with said uplink/downlink packet detection rule information, such exemplary method according to example embodiments may comprise an operation of matching said packet with forwarding rule information.

According to a variation of the procedure shown in Figure 9, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to example embodiments may comprise an operation of, if said packet matches said forwarding rule information, acting according to said forwarding rule information.

According to further example embodiments, said service identifier is a network service header.

Subsequently, the above example embodiments are described in more specific terms.

According to such example embodiments, when the PCF desires to control the service function chain related behavior of the 5GC and supports SFC split up between edge and core service function entities, the PCC rules (rules sent from PCF to SMF) and the N4 rules (rules sent from SMF to UPF) are modified as described below.

N4 is the name of the interface between a session management function (SMF) and a user plane function (UPF) and is defined in TS 29.244.

According to example embodiments, new PCC rule information from PCF instructs the SMF to deal with a service chaining that is segmented between the core and edge clouds. The SMF selects a proper set of UPF(s) for the edge services and an anchor UPF for the central services based on these PCC rules. It has to be noted that edge services may correspond to traffic offload in one edge data center and that there may be multiple such edge data centers that simultaneously apply to the PDU Session.

According to example embodiments to support this in a PCC rule, an indication of a segmented service function chain may be provided per data network access identifier (DNAI).

According to example embodiments, the PCF may provide different PCC rules to the SMF, where for one rule the AF influenced Traffic Steering Enforcement Control contains at least a DNAI and an indication of a segmented service function chain because there is a segmented service function chain for traffic offloaded to this DNAI, and for one other rule the AF influenced Traffic Steering Enforcement Control contains a DNAI and no indication of a segmented service function chain because there is no segmented service function chain for traffic offloaded to this DNAI.

According to further example embodiments, the PCF may provide different PCC rules to the SMF, where for one rule there is no AF influenced Traffic Steering Enforcement Control but a N6-1-AN Traffic Steering Enforcement Control information with no indication of a segmented service function chain because there is no segmented service function chain for traffic not being offloaded, and for another rule the AF influenced Traffic Steering Enforcement Control contains a DNAI and an indication of a segmented service function chain because there is segmented service function chain for traffic offloaded to this DNAI.

Hence, the above-quoted table of 3GPP TS 23.503 (Table 6.3.1) defining policy and charging control (PCC) rule information in 5GC may be modified in line with example embodiments as follows.

Here, in particular the last lines may be added.

It is noted that, according to example embodiments, these policy control rules can be changed dynamically by the AF through Nnef_TrafficInfluence API of TS 29.522, if, for example, the UE wants to have better QoS by using edge services.

According to example embodiments, applications/services can be grouped into edge segments and core segments to be shared across different end to end services chains and their user as indicated by said policy charging control rule information; then based on the indication of a segmented service function chain the SMF is to create N4 rules (PDR/FAR) enforcing that once UL traffic has been handled by and received from the edge based group of applications it can be properly directed to the core network based group of applications via the inter UPF (GTP-u) tunnel associated with the corresponding UE.

According to further example embodiments, the SMF provides UL/DL packet detection rules (PDR) to forward packets between edge and core associated N 9/6- interfaces. According to example embodiments, the rules are provided over interface N4.

Figure 11 shows a schematic diagram of an example of a system environment with interfaces between network entities according to example embodiments. In particular, Figure 11 illustrates 3GPP interfaces relevant for decomposed service chains between edge and core.

According to example embodiments, the UPF (I-UPF-LBO and/or UPF-PSA in Figure 11, depending on the deployment case) may implement a RFC 7665 service chain classifier function (SCF) that adds a network service header (NSH) or similar identifier and transport encapsulation to a matching service data flow.

This may be controlled by the PCF sending evolved "Per DNAI: N6 traffic routing information" within a PCC rule (as defined in 3GPP TS 23.503 Table 6.3.1: "The PCC rule information in 5GC") where the PCF may explicitly refer to NSH values or service path ID (and not implicitly as per R16 TS29.244) to be used when forwarding traffic to a service function chain over N6.

This information received in evolved "Per DNAI: N6 traffic routing information" within a PCC rule may be propagated by the SMF (via FAR rule sent) to the UPF interfacing a Service Function Chain which can be any Service Function Chain of the Figure 10.

According to further example embodiments, the FAR rules (sent from SMF over the N4 interface) can explicitly refer to NSH values or service path ID (and not implicitly as per R16 TS29.244) to be used by UPF when forwarding traffic over N6.

New information carried within N6 traffic routing information can be used for the SMF to indicate the NSH values or service path ID to be added by the SF classifier functionality of 5GC (in UPF). According to example embodiments, this may apply regardless of whether the service function chain handling applies at central N6, at edge/local N6 or is split up between these two N6 interfaces.

According to example embodiments, the last service function (SF) (SF-n in Figure 11) of the first service chain segment (SF-1 to SF-n, in the Figure 11) may complete the service processing by removing the service flow (e.g. NSH) encapsulation and sends the packet either back to the UE, or to the destination of the packet (broken curve in Figure 10). If the last SF of the first service chain segment (SF-n in Figure 11) is not the last SF of the whole end-to-end service chain (i.e. the packet is to be processed by the core SF chain as well), according to example embodiments, the last SF of the first service chain segment sends the packet to the local break-out UPF (that appears as an auxiliary of a service function forwarder (SFF)). The local break-out UPF needs to forward the packet over N9 interface to the central service chain for further processing based using the UE specific GTP-U tunnel.

To do so, according to example embodiments, this UPF is configured with

- A PDR to detect such traffic. This PDR is defined as explained below.

- A corresponding FAR that refers to GTP-U encapsulation and may be defined according to R-16 specifications.

According to example embodiments, the above-mentioned PDR is defined to relate on

- a specific packet detection information (PDI)/traffic filter that instructs the UPF to look up the UE (User Equipment) address (e.g. UE IP as an example of a terminal identifier) from the inner IP packet of the service flow, e.g. an NSH encapsulated packet, and thus to skip the NSH header for the sake of PDR related filtering, or

- UPF detection of the UE (User Equipment) ID (e.g. UE IP as an example) from the service flow (e.g. NSH) encapsulation header as metadata.

Figure 12 shows a schematic diagram of signaling sequences according to example embodiments. In particular, Figure 12 illustrates a flowchart of user plane packet processing according to example embodiments.

Based on Figure 12, exemplary user plane events as packets flow from the UE to the first service chain segment in the edge and from there to the core service chain segment according to example embodiments are described. Presumption is that the SMF has set service data flow detection filters in the LBO-UPF.

According to example embodiments, these filters can be based on IP 5-Tuple, application ID or other operator policies as defined e.g. in TS 23.503.

If the traffic flow matches the filters, according to example embodiments, a forwarding rule (FAR) set by the SMF is applied to redirect the packets of the service flow to the LBO-N6 and to the service classification function (SCF) of the edge service chain (SCF can be co-located with the LBO-UPF).

If a packet matches to Packet Detection Rule PDR (e.g. (DA=some Edge Application Server EAS address) on UL N3/N9 TEID of the UE), then, according to example embodiments, a Forwarding Action Rule "FAR = send to local N6 and to SFC" is applied. Otherwise, according to example embodiments, an "FAR = send to N9 tunnel of the UE towards PSA UPF (UPF- PSA, per R16 specifications)" is applied. The FAR rule "FAR = send to local N6 and to SFC" (that has been received from SMF over the N4 interface) can explicitly refer to NSH values or service path ID (and not implicitly as per R16 TS29.244) to be used by the UPF when forwarding traffic over N6. In this way the UPF acts as a Service Flow Classifier

According to example embodiments, the SFC encapsulates the packet with a relevant transport header and NSH as needed and sends the packet to be processed by the first service function (SF-1) of the first segment of the service chain.

The FAR definition is upgraded to allow the PCF (via the SMF) to provide information needed by a co-located SF classifier (as explained above about the FAR rule "FAR = send to local N6 and to SFC").

The packet is then processed within the first SFC segment by the service functions from SF-1 to SF-n. The service Forwarder of the edge network service function chain segment may, after last SF (SF-n) of the edge service chain has processed a packet, decide whether the packet needs to be further processed by the core network service function chain segment.

If the packet is not to be processed by the core SFC, the SF chain header (e.g. NSH) has been removed and the packet is forwarded to the destination of the original packet or to the UE as per R16 specifications (for the case where the packet is to be sent back to the UE). According to example embodiments, the PDR for this would be "destination= UE IP address, source = original destination (EAS address), incoming interface= LBO-N6" and the FAR would point towards the GTP-U tunnel towards the UE (broken curve/service path of Figure 10).

On the other hand, if the packet is to be processed by the core SFC (as according to the present concept), e.g. if the last SF of the service chain segment (SF-n in Figure 11) or the Service Function Forwarder decides that the packet needs further processing by the core SFC segment, then if NSH is used, according to example embodiments, the NSH is not removed. The packet is sent to LBO-UPF that is also acting as an auxiliary of SFF (Service Function Forwarding). In this case the packet still carries SF (Service Flow) chain related header. According to example embodiments, the PDR for this would be "(bypass SFC header, source IP address = UE IP address, destination= original destination = EAS, incoming interface= LBO-N6)". Based on this information/filters, according to example embodiments, the UPF applies a FAR (received from SMF) that requests it to encapsulate the packet and sends it to the N9 GTP-U tunnel to the central UPF corresponding to the PDU session from the UE (solid curve/service path of Figure 10). The case where transport header is used instead of NSH is described in more detail in the following. The UE ID can be carried in the metadata of the NSH (i.e. context header of the NSH), or the UPF acting as SFF auxiliary (auxiliary Service Flow Forwarder) can find out the UE ID based on the PDR rule containing indication where UE IP address can be found in the encapsulated packet and then based on the associated FAR received from SMF select the right N9-tunnel matching the PDU Session of the UE.

For example, the SFF (or LBO-UFP if they are co-located) may find the UE IP address from the source address of the inner encapsulated IP packet.

After possible reclassification at the central N6, according to example embodiments, the packet is processed in the central SFC in normal manner.

If the chain is completed the SFC, terminates there.

For DL traffic, once traffic has been processed by the core network segment of the service Flow Chain, Service Flow Forwarding of the core network SFC segment may decide that the packet needs to be sent to the edge SFC segment for further processing. The UE ID information (UE IP address) is provided using either of the above-presented mechanisms, namely, embedding the UE ID into NSH context metadata or in the UE IP address in the encapsulated inner packet.

If the DL packet is not to be processed by the edge SFC, the SF chain header (e.g. NSH) has been removed and the packet is forwarded to the UE as per R16 specifications. According to example embodiments, the PDR for this would be "destination= UE IP address, source = original destination (EAS address), incoming interface= N6" and the FAR would point towards the GTP- U tunnel towards the UE (dotted curve/service path of Figure 10).

On the other hand, if the packet is to be processed by the edge SFC (as according to the present concept), i.e. if after the last SF of the core service chain segment has processed the packet it is decided that the packet needs further processing by the edge SFC segment, then if NSH is used, according to example embodiments, the NSH is not removed and the destination of the outer IP packet is set to the edge SFC. The packet is sent to central PF that is also acting as an auxiliary of SFF (Service Function Forwarding). In this case the packet still carries SF (Service Flow) chain related header. According to example embodiments, the PDR handled by the central UPF for this would be "(bypass SFC header, destination IP address = UE IP address, source= = EAS, incoming interface= N6)". Based on this information/filters, according to example embodiments, the UPF applies a FAR (received from SMF) that requests it to encapsulate the packet and sends it to the N9 GTP-U tunnel to the edge UPF corresponding to the PDU session from the UE (solid curve/service path of Figure 10). The case where transport header is used instead of NSH is described in more detail in the following.

The above-described procedures and functions may be implemented by respective functional elements, processors, or the like, as described below.

In the foregoing exemplary description of the network entity, only the units that are relevant for understanding the principles of the disclosure have been described using functional blocks. The network entity may comprise further units that are necessary for its respective operation. However, a description of these units is omitted in this specification. The arrangement of the functional blocks of the devices is not construed to limit the disclosure, and the functions may be performed by one block or further split into sub-blocks.

When in the foregoing description it is stated that the apparatus, i.e. network entity (or some other means) is configured to perform some function, this is to be construed to be equivalent to a description stating that a (i.e. at least one) processor or corresponding circuitry, potentially in cooperation with computer program code stored in the memory of the respective apparatus, is configured to cause the apparatus to perform at least the thus mentioned function. Also, such function is to be construed to be equivalently implementable by specifically configured circuitry or means for performing the respective function (i.e. the expression "unit configured to" is construed to be equivalent to an expression such as "means for").

In Figure 13, an alternative illustration of apparatuses according to example embodiments is depicted. As indicated in Figure 13, according to example embodiments, the apparatus (network entity) 10' (corresponding to the network entity 10) comprises a processor 1311, a memory 1312 and an interface 1313, which are connected by a bus 1314 or the like. Further, according to example embodiments, the apparatus (network entity) 30' (corresponding to the network entity 30) comprises a processor 1331, a memory 1332 and an interface 1333, which are connected by a bus 1334 or the like. Further, according to example embodiments, the apparatus (network entity) 50' (corresponding to the network entity 50) comprises a processor 1351, a memory 1352 and an interface 1353, which are connected by a bus 1354 or the like. The apparatuses may be connected via links 130a, 130b, respectively.

The processor 1311/1331/1351 and/or the interface 1313/1333/1353 may also include a modem or the like to facilitate communication over a (hardwire or wireless) link, respectively. The interface 1313/1333/1353 may include a suitable transceiver coupled to one or more antennas or communication means for (hardwire or wireless) communications with the linked or connected device(s), respectively. The interface 1313/1333/1353 is generally configured to communicate with at least one other apparatus, i.e. the interface thereof.

The memory 1312/1332/1352 may store respective programs assumed to include program instructions or computer program code that, when executed by the respective processor, enables the respective electronic device or apparatus to operate in accordance with the example embodiments.

In general terms, the respective devices/apparatuses (and/or parts thereof) may represent means for performing respective operations and/or exhibiting respective functionalities, and/or the respective devices (and/or parts thereof) may have functions for performing respective operations and/or exhibiting respective functionalities.

When in the subsequent description it is stated that the processor (or some other means) is configured to perform some function, this is to be construed to be equivalent to a description stating that at least one processor, potentially in cooperation with computer program code stored in the memory of the respective apparatus, is configured to cause the apparatus to perform at least the thus mentioned function. Also, such function is to be construed to be equivalently implementable by specifically configured means for performing the respective function (i.e. the expression "processor configured to [cause the apparatus to] perform xxx-ing" is construed to be equivalent to an expression such as "means for xxx-ing").

According to example embodiments, an apparatus representing the network entity 10 comprises at least one processor 1311, at least one memory 1312 including computer program code, and at least one interface 1313 configured for communication with at least another apparatus. The processor (i.e. the at least one processor 1311, with the at least one memory 1312 and the computer program code) is configured to perform transmitting policy charging control rule information towards a session management function entity (thus the apparatus comprising corresponding means for transmitting), wherein said policy charging control rule information is indicative of a segmented service function chain, and said segmented service function chain is segmented into a first segment and a second segment.

According to example embodiments, an apparatus representing the network entity 30 comprises at least one processor 1331, at least one memory 1332 including computer program code, and at least one interface 1333 configured for communication with at least another apparatus. The processor (i.e. the at least one processor 1331, with the at least one memory 1332 and the computer program code) is configured to perform receiving policy charging control rule information from a policy control function entity (thus the apparatus comprising corresponding means for receiving), wherein said policy charging control rule information is indicative of a segmented service function chain, and said segmented service function chain is segmented into a first segment and a second segment.

According to example embodiments, an apparatus representing the network entity 50 comprises at least one processor 1351, at least one memory 1352 including computer program code, and at least one interface 1353 configured for communication with at least another apparatus. The processor (i.e. the at least one processor 1351, with the at least one memory 1352 and the computer program code) is configured to perform (at a user plane function entity interfacing with application services of a segment of a segmented service function chain) receiving, from a session management function entity, mappings between uplink/downlink packet detection rule information and a forwarding rule information containing a service function chain identifier, or to perform receiving, from a session management function entity, uplink/downlink packet detection rule information indicative of forwarding between an interface towards core network based application services and an interface towards network edge based application services (thus the apparatus comprising corresponding means for receiving), or to perform receiving, from a session management function entity, forwarding rule information to be used for forwarding between an interface towards core network based application services and an interface towards network edge based application services (thus the apparatus comprising corresponding means for receiving).

For further details regarding the operability/functionality of the individual apparatuses, reference is made to the above description in connection with any one of Figures 1 to 12, respectively.

For the purpose of the present disclosure as described herein above, it should be noted that - method steps likely to be implemented as software code portions and being run using a processor at a network server or network entity (as examples of devices, apparatuses and/or modules thereof, or as examples of entities including apparatuses and/or modules therefore), are software code independent and can be specified using any known or future developed programming language as long as the functionality defined by the method steps is preserved;

- generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the embodiments and its modification in terms of the functionality implemented;

- method steps and/or devices, units or means likely to be implemented as hardware components at the above-defined apparatuses, or any module(s) thereof, (e.g., devices carrying out the functions of the apparatuses according to the embodiments as described above) are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL (Transistor-Transistor Logic), etc., using for example ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components;

- devices, units or means (e.g. the above-defined network entity or network register, or any one of their respective units/means) can be implemented as individual devices, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device, unit or means is preserved;

- an apparatus like the user equipment and the network entity /network register may be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of an apparatus or module, instead of being hardware implemented, be implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for execution/being run on a processor;

- a device may be regarded as an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example.

In general, it is to be noted that respective functional blocks or elements according to above-described aspects can be implemented by any known means, either in hardware and/or software, respectively, if it is only adapted to perform the described functions of the respective parts. The mentioned method steps can be realized in individual functional blocks or by individual devices, or one or more of the method steps can be realized in a single functional block or by a single device.

Generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the present disclosure. Devices and means can be implemented as individual devices, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device is preserved. Such and similar principles are to be considered as known to a skilled person.

Software in the sense of the present description comprises software code as such comprising code means or portions or a computer program or a computer program product for performing the respective functions, as well as software (or a computer program or a computer program product) embodied on a tangible medium such as a computer-readable (storage) medium having stored thereon a respective data structure or code means/portions or embodied in a signal or in a chip, potentially during processing thereof.

The present disclosure also covers any conceivable combination of method steps and operations described above, and any conceivable combination of nodes, apparatuses, modules or elements described above, as long as the above-described concepts of methodology and structural arrangement are applicable.

In view of the above, there are provided measures for coordination of segmented service chains. Such measures exemplarily comprise, at a user plane function entity interfacing with application services of a segment of a segmented service function chain, receiving, from a session management function entity, uplink/downlink packet detection rule information indicative of forwarding between an interface towards core network based application services and an interface towards network edge based application services.

Even though the disclosure is described above with reference to the examples according to the accompanying drawings, it is to be understood that the disclosure is not restricted thereto. Rather, it is apparent to those skilled in the art that the present disclosure can be modified in many ways without departing from the scope of the inventive idea as disclosed herein.

List of acronyms and abbreviations

3GPP Third Generation Partnership Project

5GC 5G core network

5GS 5G system

5G-AN 5G access network

AF application function

AMF access and mobility management function

API application programming interface

AR augmented reality

BP branching point

BSF binding support function

DA destination address

DL downlink

DN data network DNAI data network access identifier

DNN data network name

EAS edge application server

EPC evolved packet core

FAR forwarding rule

FMSS flexible mobile service steering

IETF Internet Engineering Task Force

LBO local breakout

LTE Long Term Evolution

NEF network exposure function

NAT network address translation

NSH network service header

PCC policy and charging control

PCF policy control function

PFCP packet forwarding control protocol

PDI packet detection information

PDR packet detection rule

PDU packet data unit

PSA PDU session anchor/UPF functionality at the border (N6) of the DN

QoE quality of experience

(R)AN (radio) access network

SCF service classification function

SF service function

SFF service function forwarder

SFC service function chain, service flow chaining

SMF session management function

S-NSSAI single network slice selection assistance information

TEID tunnel endpoint identifier

UE user equipment

UDM unified data management

UDR unified data repository

UL uplink UL CL uplink classifier

UPF user plane function

VR virtual reality