Application traffic routing in distributed networks

Abstract

This disclosure provides a method for routing of application traffic between a local and a central part of a Distributed Network, DN. The method comprises transmitting from a first network node to a second network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers (DNAIs), the first tunnel request including at least one supported tunneling mechanism or protocol; transmitting from the second network node to a third network node a second tunnel request including the at least one supported tunneling mechanism or protocol and the two DNAIs; selecting at the third network node one of the at least one supported tunneling mechanism or protocol; determining at the third network node a first and a second User Plane Function (UPF) as the tunnel endpoints based on the DNAIs and the selected tunneling mechanism or protocol, particularly wherein the first UPF or the second UPF is a UPF in a central part of the DN or a local part of the DN; initiating at the third network node a N4 Session Establishment procedure with the first UPF, wherein the initiating further comprises receiving at the SMF from the first UPF an N4 Session Establishment Response including a Tunnel Endpoint Identifier (TEID) for uplink traffic of the tunnel, particularly wherein the TEID is selected by the first UPF; initiating at the third network node a N4 Session Establishment procedure with the second UPF to provide the TEID for uplink traffic of the tunnel and an IP tunnel endpoint address for uplink traffic, particularly wherein the IP tunnel endpoint address is obtained from an UPF or configured in the SMF, and particularly wherein the IP tunnel endpoint address further comprises a port number; transmitting from the third network node to the second network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address; and transmitting from the second network node to the first network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address.

Description

[0001] APPLICATION TRAFFIC ROUTING IN DISTRIBUTED NETWORKS

[0002] TECHNICAL FIELD

[0003] The present invention generally relates to communications or mobile networks, and more specifically, the present invention relates to routing of application traffic between the local and central parts of Distributed Networks (DN) in a communications network.

[0004] BACKGROUND

[0005] In telecommunications or communications networks, particularly Fifth Generation (5G) networks, a Distributed Network (DN) is a decentralized network, where data processing and traffic routing are distributed across various nodes or locations within the network. This architecture is designed to improve data throughput, reduce latency, and enhance the overall efficiency of network communication. Application traffic within these networks encompasses data exchanged between a User Equipment (UE) and Application Servers (AS). Traffic routing in this context refers to the mechanisms and protocols employed to direct data packets from their source to their destination through the most optimal paths within the network.

[0006] Edge Computing (EC) brings computation and data storage closer to the location where it is needed or requested, to improve response times and save bandwidth. The integration of edge computing with distributed networks facilitates the processing of data at the edge of the network, nearest to the end-users. This approach is particularly beneficial for applications requiring real-time processing and analysis, as it significantly reduces the latency involved in sending data to centralized data centers for processing.

[0007] Tunneling mechanisms, such as Generic Routing Encapsulation (GRE) and IP-in-IP (IP stands for Internet Protocol), are used to encapsulate data packets, allowing for data transmission across diverse network infrastructures. These mechanisms create network paths and ensure the secure and efficient transfer of data across different segments of a distributed network. Third Generation Partnership Project (3GPP) specifications address the efficient routing of application traffic within Distributed Networks (DN), especially between their local and central parts or segments. The scenarios require traffic processing at the network edge, followed by subsequent forwarding to a central Application Server for additional processing, in situations where direct paths between local and central DN components do not exist.

[0008] A problematic aspect of the existing solutions is the routing across disjoint IP networks. In conventional IP networking scenarios, routers facilitate the exchange of information regarding destination reachability through routing protocols. However, when two IP networks are disjoint or do not have a direct connectivity path, no routing information can be exchanged between them, rendering direct communication using IP addresses across these networks impossible. For instance, see Figure 2, an Edge Application Server (EAS) within IP Network 1 , cannot transmit IP packets to an Edge Application Server (EAS) in IP Network 2, if there is no routing connection between the two networks. Consequently, the EAS within IP Network 1 needs to utilize an address within IP Network 1 for such communications.

[0009] Additionally, the deployment of Network Address Translation (NAT) between the User Plane Function (UPF) and the Distributed Network (DN) complicates the routing of outgoing traffic from a UPF, typically requiring the use of NAT for communications exiting the UPF. The dashed arrow in Figure 2 illustrates the problematic aspect described above.

[0010] SUMMARY

[0011] The invention is set out in the appended set of claims.

[0012] An object of the invention is to enable routing of application traffic between the local and central parts of a Distributed Network (DN) when there is no direct connectivity by leveraging tunneling mechanisms such as GRE and I P-in-IP, thus interconnecting disjoint IP networks for application traffic.

[0013] This disclosure provides a method for routing of application traffic between a local and a central part of a Distributed Network, DN. The method comprises transmitting from a first network node to a second network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers (DNAIs), the first tunnel request including at least one supported tunneling mechanism or protocol; transmitting from the second network node to a third network node a second tunnel request including the at least one supported tunneling mechanism or protocol and the two DNAIs; selecting at the third network node one of the at least one supported tunneling mechanism or protocol; determining at the third network node a first and a second User Plane Function (UPF) as the tunnel endpoints based on the DNAIs and the selected tunneling mechanism or protocol, particularly wherein the first UPF or the second UPF is a UPF in a central part of the DN or a local part of the DN; initiating at the third network node a N4 Session Establishment procedure with the first UPF, wherein the initiating further comprises receiving at the SMF from the first UPF an N4 Session Establishment Response including a Tunnel Endpoint Identifier (TEID) for uplink traffic of the tunnel, particularly wherein the TEID is selected by the first UPF; initiating at the third network node a N4 Session Establishment procedure with the second UPF to provide the TEID for uplink traffic of the tunnel and an IP tunnel endpoint address for uplink traffic, particularly wherein the IP tunnel endpoint address is obtained from an UPF or configured in the SMF, and particularly wherein the IP tunnel endpoint address further comprises a port number; transmitting from the third network node to the second network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address; and transmitting from the second network node to the first network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address. In some embodiments, the method further comprises determining at the second network node the two DNAIs based on the first tunnel request, particularly wherein determining at the second network node the two DNAIs comprises receiving at the second network node from the first network node the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs). In some embodiments, the first or second tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption (MASQUE) support. In some embodiments, the first and / or second tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs) of the EAS. In some embodiments, the method further comprises determining at the second network node the two DNAIs based on the first tunnel request. In some embodiments, the method further comprises determining at the second network node an SMF supporting the two DNAIs based on the first tunnel request. In some embodiments, the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation (GRE) and I P-in-IP tunneling mechanisms. In some embodiments, the method further comprises the selection of Tunnel Endpoint Identifiers (TEIDs) for both UL and DL traffic. In some embodiments, the local and a central part of the Distributed Network (DN) are disjoint IP networks without direct connectivity. In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF), the second network node is a Network Exposure Function (NEF), and the third network node is a Session Management Function (SMF).

[0014] An aspect of the invention relates to a method performed by a first network node for routing of application traffic between a local and a central part of a Distributed Network, DN. The method comprises transmitting from a first network node to a second network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers (DNAIs), the first tunnel request including at least one supported tunneling mechanism or protocol; and receiving at the first network node from the second network node a tunnel response including a selected tunneling mechanism or protocol and the IP tunnel endpoint address. In some embodiments, the first tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support. In some embodiments, the first tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs) of the EAS. In some embodiments, the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation (GRE) and IP-in-IP tunneling mechanisms. In some embodiments, the local and a central part of the Distributed Network (DN) are disjoint IP networks without direct connectivity. In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF), and the second network node is a Network Exposure Function (NEF).

[0015] An aspect of the invention relates to a method performed by a second network node for routing of application traffic between a local and a central part of a Distributed Network, DN. The method comprises receiving at a second network node from a first network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers (DNAIs), the first tunnel request including at least one supported tunneling mechanism or protocol; transmitting from the second network node to a third network node a second tunnel request including the at least one supported tunneling mechanism or protocol and the two DNAIs; receiving at the second network node from the third network node a tunnel response including a selected tunneling mechanism or protocol and the IP tunnel endpoint address; and transmitting from the second network node to the first network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address. In some embodiments, the method further comprises determining at the second network node the two DNAIs based on the first tunnel request, particularly wherein determining at the second network node the two DNAIs comprises receiving at the second network node from the first network node the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs). In some embodiments, the first or second tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support. In some embodiments, the first and / or second tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs) of the EAS. In some embodiments, the method further comprises determining at the second network node the two DNAIs based on the first tunnel request. In some embodiments, the method further comprises determining at the second network node an SMF supporting the two DNAIs based on the first tunnel request. In some embodiments, the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation (GRE) and I P-in-IP tunneling mechanisms. In some embodiments, the method further comprises the selection of Tunnel Endpoint Identifiers (TEIDs) for both UL and DL traffic. In some embodiments, the local and a central part of the Distributed Network (DN) are disjoint IP networks without direct connectivity. In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF), the second network node is a Network Exposure Function (NEF), and the third network node is a Session Management Function (SMF).

[0016] An aspect of the invention relates to a method performed by a third network node for routing of application traffic between a local and a central part of a Distributed Network, DN. The method comprises receiving at a third network node from a second network node a second tunnel request including at least one supported tunneling mechanism or protocol and two DNAIs; selecting at the third network node one of the at least one supported tunneling mechanism or protocol; determining at the third network node a first and a second User Plane Function (UPF) as the tunnel endpoints based on the DNAIs and the selected tunneling mechanism or protocol, particularly wherein the first UPF or the second UPF is a UPF in a central part of the DN or a local part of the DN; initiating at the third network node a N4 Session Establishment procedure with the first UPF, wherein the initiating further comprises receiving at the SMF from the first UPF an N4 Session Establishment Response including a Tunnel Endpoint Identifier (TEID) for uplink traffic of the tunnel, particularly wherein the TEID is selected by the first UPF; initiating at the third network node a N4 Session Establishment procedure with the second UPF to provide the TEID for uplink traffic of the tunnel and an IP tunnel endpoint address for uplink traffic, particularly wherein the IP tunnel endpoint address is obtained from an UPF or configured in the SMF, and particularly wherein the IP tunnel endpoint address further comprises a port number; and transmitting from the third network node to the second network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address. In some embodiments, the second tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support. In some embodiments, the second tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs) of the EAS. In some embodiments, the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation (GRE) and IP-in-IP tunneling mechanisms. In some embodiments, the method further comprises the selection of Tunnel Endpoint Identifiers (TEIDs) for both UL and DL traffic. In some embodiments, the local and a central part of the Distributed Network (DN) are disjoint IP networks without direct connectivity. In some embodiments, the second network node is a Network Exposure Function (NEF), and the third network node is a Session Management Function (SMF).

[0017] Other aspects of the invention relate to mobile network nodes, particularly a third network node (107, 900), a second network node (109, 800), a first network node (113, 700) configured to perform the respective methods as described herein. Other aspects of the invention relate to computer program and computer program products.

[0018] In some embodiments, the third network node is a Session Management Function (SMF). In some embodiments, the second network node is a Network Exposure Function (NEF). In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF).

[0019] Advantageously, the tunnel setup between two networks to which User Plane Functions (UPFs) are connected is independent of any other features or mechanisms, such as edge computing mechanisms detailed in 3GPP specifications.

[0020] Further advantageously, the Edge Application Server (EAS) or Application Function (AF) is enabled to specify its supported tunnel types within the request, enabling the tailored routing of IP packets to the remote end.

[0021] Additional objectives, features and advantages of the concepts disclosed herein will be apparent from the following description, claims and drawings, or may be learned by practice of the described technologies and concepts as set forth herein." BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to best describe the manner in which the disclosed concepts may be implemented, as well as define other objects, advantages and features of the disclosure, a more particular description is provided below and is illustrated in the appended drawings. Understanding that these drawings depict only exemplary embodiments of the invention and are not therefore to be considered to be limiting in scope, the examples will be described and explained with additional specificity and detail through the use of the accompanying drawings.

[0023] Figure 1 illustrates an example networked system in accordance with particular embodiments of the solution described herein.

[0024] Figure 2 illustrates an example block diagram showing network entities in a mobile communications network according to particular embodiments of the solution described herein.

[0025] Figure 3 illustrates an example signaling diagram showing a procedure according to particular embodiments of the solution described herein.

[0026] Figure 4 illustrates an example flowchart showing a method performed by a mobile network node according to particular embodiments of the solution described herein.

[0027] Figure 5 illustrates an example flowchart showing a method performed by a mobile network node according to particular embodiments of the solution described herein.

[0028] Figure 6 illustrates an example flowchart showing a method performed by a mobile network node according to particular embodiments of the solution described herein.

[0029] Figure 7 illustrates an example block diagram of a mobile network node configured in accordance with particular embodiments of the solution described herein.

[0030] Figure 8 illustrates an example block diagram of a mobile network node configured in accordance with particular embodiments of the solution described herein.

[0031] Figure 9 illustrates an example block diagram of a mobile network node configured in accordance with particular embodiments of the solution described herein.

[0032] Figure 10 illustrates an example block diagram of a virtualized environment. DETAILED DESCRIPTION

[0033] The invention will now be described in detail hereinafter with reference to the accompanying drawings, in which examples of embodiments or implementations of the invention are shown. The invention may, however, be embodied or implemented in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of present invention to those skilled in the art. It should also be noted that these embodiments are not mutually exclusive. Components from one embodiment may be tacitly assumed to be present / used in another embodiment. These embodiments of the disclosed subject matter are presented as teaching examples and are not to be construed as limiting the scope of the disclosed subject matter. For example, certain details of the described embodiments may be modified, omitted, or expanded upon without departing from the scope of the described subject matter.

[0034] The example embodiments described herein arise in the context of a telecommunications network, including but not limited to a telecommunications network that conforms to and / or otherwise incorporates aspects of a fifth generation (5G) architecture. Figure 1 is an example networked system 100 in accordance with example embodiments of the present disclosure. Figure 1 specifically illustrates User Equipment (UE) 101 , which may be in communication with a (Radio) Access Network (RAN) 102 and Access and Mobility Management Function (AMF) 106 and User Plane Function (UPF) 103. The AMF 106 may, in turn, be in communication with core network services including Session Management Function (SMF) 107 and Policy Control Function (PCF) 111. The core network services may also be in communication with an Edge Application Server / Application Function (EAS / AF) 113. Other networked services also include Network Slice Selection Function (NSSF) 108, Authentication Server Function (AUSF) 105, User Data Management (UDM) 112, Network Exposure Function (NEF) 109, Network Repository Function (NRF) 110 and Data Network (DN) 104. In some example implementations of embodiments of the present disclosure, each one of the entities in the networked system 100 are considered to be a Network Function (NF). One or more additional instances of the NFs may be incorporated into the networked system.

[0035] The solution described herein aims to enable routing of application traffic between the local and central parts of a Distributed Network (DN) when there is no direct connectivity by leveraging tunneling mechanisms such as GRE and IP-in-IP, thus interconnecting disjoint IP networks for application traffic.

[0036] This disclosure provides a method for routing of application traffic between a local and a central part of a Distributed Network, DN. The method comprises transmitting from a first network node to a second network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers (DNAIs), the first tunnel request including at least one supported tunneling mechanism or protocol; transmitting from the second network node to a third network node a second tunnel request including the at least one supported tunneling mechanism or protocol and the two DNAIs; selecting at the third network node one of the at least one supported tunneling mechanism or protocol; determining at the third network node a first and a second User Plane Function (UPF) as the tunnel endpoints based on the DNAIs and the selected tunneling mechanism or protocol, particularly wherein the first UPF or the second UPF is a UPF in a central part of the DN or a local part of the DN; initiating at the third network node a N4 Session Establishment procedure with the first UPF, wherein the initiating further comprises receiving at the SMF from the first UPF an N4 Session Establishment Response including a Tunnel Endpoint Identifier (TEID) for uplink traffic of the tunnel, particularly wherein the TEID is selected by the first UPF; initiating at the third network node a N4 Session Establishment procedure with the second UPF to provide the TEID for uplink traffic of the tunnel and an IP tunnel endpoint address for uplink traffic, particularly wherein the IP tunnel endpoint address is obtained from an UPF or configured in the SMF, and particularly wherein the IP tunnel endpoint address further comprises a port number; transmitting from the third network node to the second network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address; and transmitting from the second network node to the first network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address. In some embodiments, the method further comprises determining at the second network node the two DNAIs based on the first tunnel request, particularly wherein determining at the second network node the two DNAIs comprises receiving at the second network node from the first network node the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs). In some embodiments, the first or second tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support. In some embodiments, the first and / or second tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs) of the EAS. In some embodiments, the method further comprises determining at the second network node the two DNAIs based on the first tunnel request. In some embodiments, the method further comprises determining at the second network node an SMF supporting the two DNAIs based on the first tunnel request. In some embodiments, the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation (GRE) and IP-in-IP tunneling mechanisms. In some embodiments, the method further comprises the selection of Tunnel Endpoint Identifiers (TEIDs) for both UL and DL traffic. In some embodiments, the local and a central part of the Distributed Network (DN) are disjoint IP networks without direct connectivity. In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF), the second network node is a Network Exposure Function (NEF), and the third network node is a Session Management Function (SMF).

[0037] An aspect of the invention relates to a method performed by a first network node for routing of application traffic between a local and a central part of a Distributed Network, DN. The method comprises transmitting from a first network node to a second network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers (DNAIs), the first tunnel request including at least one supported tunneling mechanism or protocol; and receiving at the first network node from the second network node a tunnel response including a selected tunneling mechanism or protocol and the IP tunnel endpoint address. In some embodiments, the first tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support. In some embodiments, the first tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs) of the EAS. In some embodiments, the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation (GRE) and IP-in-IP tunneling mechanisms. In some embodiments, the local and a central part of the Distributed Network (DN) are disjoint IP networks without direct connectivity. In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF), and the second network node is a Network Exposure Function (NEF).

[0038] An aspect of the invention relates to a method performed by a second network node for routing of application traffic between a local and a central part of a Distributed Network, DN. The method comprises receiving at a second network node from a first network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers (DNAIs), the first tunnel request including at least one supported tunneling mechanism or protocol; transmitting from the second network node to a third network node a second tunnel request including the at least one supported tunneling mechanism or protocol and the two DNAIs; receiving at the second network node from the third network node a tunnel response including a selected tunneling mechanism or protocol and the IP tunnel endpoint address; and transmitting from the second network node to the first network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address. In some embodiments, the method further comprises determining at the second network node the two DNAIs based on the first tunnel request, particularly wherein determining at the second network node the two DNAIs comprises receiving at the second network node from the first network node the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs). In some embodiments, the first or second tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support. In some embodiments, the first and / or second tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs) of the EAS. In some embodiments, the method further comprises determining at the second network node the two DNAIs based on the first tunnel request. In some embodiments, the method further comprises determining at the second network node an SMF supporting the two DNAIs based on the first tunnel request. In some embodiments, the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation (GRE) and I P-in-IP tunneling mechanisms. In some embodiments, the method further comprises the selection of Tunnel Endpoint Identifiers (TEIDs) for both UL and DL traffic. In some embodiments, the local and a central part of the Distributed Network (DN) are disjoint IP networks without direct connectivity. In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF), the second network node is a Network Exposure Function (NEF), and the third network node is a Session Management Function (SMF).

[0039] An aspect of the invention relates to a method performed by a third network node for routing of application traffic between a local and a central part of a Distributed Network, DN. The method comprises receiving at a third network node from a second network node a second tunnel request including at least one supported tunneling mechanism or protocol and two DNAIs; selecting at the third network node one of the at least one supported tunneling mechanism or protocol; determining at the third network node a first and a second User Plane Function (UPF) as the tunnel endpoints based on the DNAIs and the selected tunneling mechanism or protocol, particularly wherein the first UPF or the second UPF is a UPF in a central part of the DN or a local part of the DN; initiating at the third network node a N4 Session Establishment procedure with the first UPF, wherein the initiating further comprises receiving at the SMF from the first UPF an N4 Session Establishment Response including a Tunnel Endpoint Identifier (TEID) for uplink traffic of the tunnel, particularly wherein the TEID is selected by the first UPF; initiating at the third network node a N4 Session Establishment procedure with the second UPF to provide the TEID for uplink traffic of the tunnel and an IP tunnel endpoint address for uplink traffic, particularly wherein the IP tunnel endpoint address is obtained from an UPF or configured in the SMF, and particularly wherein the IP tunnel endpoint address further comprises a port number; and transmitting from the third network node to the second network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address. In some embodiments, the second tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support. In some embodiments, the second tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs) of the EAS. In some embodiments, the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation (GRE) and IP-in-IP tunneling mechanisms. In some embodiments, the method further comprises the selection of Tunnel Endpoint Identifiers (TEIDs) for both UL and DL traffic. In some embodiments, the local and a central part of the Distributed Network (DN) are disjoint IP networks without direct connectivity. In some embodiments, the second network node is a Network Exposure Function (NEF), and the third network node is a Session Management Function (SMF).

[0040] This disclosure also provides mobile network nodes, particularly a third network node (107, 900), a second network node (109, 800), a first network node (113, 700) configured to perform the respective methods as described herein. In some embodiments, the third network node is a Session Management Function (SMF) 107. In some embodiments, the second network node is a Network Exposure Function (NEF) 109. In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF) 113.

[0041] This disclosure also provides the corresponding computer program and computer program products comprising code, for example in the form of a computer program, that when run on processing circuitry of the mobile network nodes causes the mobile network nodes to perform the disclosed methods. Advantageously, the tunnel setup between two networks to which User Plane Functions (UPFs) are connected is independent of any other features or mechanisms, such as edge computing mechanisms detailed in 3GPP specifications.

[0042] Further advantageously, the Edge Application Server (EAS) or Application Function (AF) is enabled to specify its supported tunnel types within the request, enabling the tailored routing of IP packets to the remote end.

[0043] The solution and the features comprised therein are further described in what follows.

[0044] The present disclosure involves the Edge Application Server (EAS) or Application Function (AF) informing the 5G Core (5GC) network of the tunneling mechanisms it supports, such as GRE (Generic Routing Encapsulation) and IP-in-IP, both of which are commonly supported by most operating systems. Subsequently, the Session Management Function (SMF) selects an appropriate tunneling mechanism from this set and establishes a tunneling endpoint within the User Plane Function (UPF). The EAS / AF then initiates a request for a connection between the Data Network Access Identifiers (DNAIs), including the supported tunneling mechanisms.

[0045] Hereinafter, drawings showing examples of embodiments of the solution are described in detail.

[0046] Figure 3 is a signaling diagram illustrating a procedure for routing of application traffic between a local and a central part of a Distributed Network. The procedure is performed by a third network node (107, 900), a second network node (109, 800), a first network node (113, 700). In some embodiments, the third network node is a Session Management Function (SMF) 107. In some embodiments, the second network node is a Network Exposure Function (NEF) 109. In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF) 113. The procedure further involves two User Plane Functions, UPF1 and UPF2. The steps of the procedure are the following:

[0047] In step 1 , the AF / EAS requests 5GC to set up a tunnel between 2 DNAIs. One could also imagine that the EAS / AF only gives IP address ranges of EAS and AS, or even FQDNs of these. If not DNAIs are provided, NEF needs to translate the provided info to DNAIs. The AF / EAS provides which tunneling protocol it supports, e.g.. IP in IP, GRE, etc. This step can happen at any time e.g., at EAS boot up or restart, when a UE first access the EAS, or via a management procedure in an AF.

[0048] In step 2, the NEF finds a SMF supporting both DNAIs and sends a request to this SMF. In step 3, SMF follows steps 3a-3d. A first relevant aspect is that the SMF selects one of the tunneling methods provided by the AF / EAS (if 5GC supports at least one of them, else SMF rejects the request); a second relevant aspect is the IP tunnel endpoint address.

[0049] 3a. SMF selects one of the tunneling methods provided by the AF / EAS (if 5GC supports at least one of them, else SMF rejects the request). Then, the SMF selects two UPFs as the L-PSA (Local PDU Session Anchor) UPF and the C-PSA (Central PDU Session Anchor) UPF, based on the two retrieved DNAIs and the selected tunneling method.

[0050] 3b. The SMF initiates a N4 Session Establishment procedure with the selected C-PSA UPF. The N4 message contains Packet Detection Rule (PDR)-1 and Forwarding Action Rule (FAR)-1 for UL traffic. C-PSA UPF performs the session configuration and UL TEID (Tunnel Endpoint ID) selection. During the session configuration, UL TEID (i.e., UL TEID of the tunnel) is used for L-PSA UPF to forward L-DN's UL traffic to DN via C-PSA UPF.

[0051] 3c. The C-PSA UPF responds SMF by sending an N4 Session Establishment Response, including the UL TEID of the DN tunnel which is a part of CN tunnel information.

[0052] 3d. SMF initiates a N4 Session establishment procedure with the selected L-PSA UPF, to provide UL TEID of the tunnel to L-PSA UPF, as well as IP tunnel endpoint address and FAR-2 for UL traffic. L-PSA UPF performs the tunnel configuration and DL TEID of DN tunnel / LL-DN tunnel selection. During the tunnel configuration, DL TEID of the tunnel is selected for L-PSA UPF to forward UL traffic to C-DN via C-PSA UPF.

[0053] In step 4, the SMF responds with the selected tunnelling mechanism and the tunnel endpoint address of UPF1.

[0054] In step 5, the NEF forwards the received information from SMF to the AF / EAS

[0055] Hereinafter, flowcharts showing examples of embodiments of the solution are described in detail.

[0056] The embodiments correspond to methods performed by and involving a third network node (107, 900), a second network node (109, 800), and a first network node (113, 700). In some embodiments, the third network node is a Session Management Function (SMF) 107. In some embodiments, the second network node is a Network Exposure Function (NEF) 109. In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF) 113. Figure 4 is a flowchart illustrating a method performed by the first network node for routing of application traffic between a local and a central part of a Distributed Network, DN.

[0057] In step S-401 , the first network node transmits to a second network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers (DNAIs), the first tunnel request including at least one supported tunneling mechanism or protocol.

[0058] In step S-402, the first network node receives from the second network node a tunnel response including a selected tunneling mechanism or protocol and the IP tunnel endpoint address.

[0059] In some embodiments, the first tunnel request further includes any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support.

[0060] In some embodiments, the first tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs) of the EAS.

[0061] In some embodiments, the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation (GRE) and IP-in-IP tunneling mechanisms.

[0062] In some embodiments, the local and a central part of the Distributed Network (DN) are disjoint IP networks without direct connectivity.

[0063] In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF), and the second network node is a Network Exposure Function (NEF).

[0064] Figure 5 is a flowchart illustrating a method performed by the second network node for routing of application traffic between a local and a central part of a Distributed Network, DN.

[0065] In step S-501 , the second network node receives from a first network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers (DNAIs), the first tunnel request including at least one supported tunneling mechanism or protocol.

[0066] In step S-502, the second network node transmits to a third network node a second tunnel request including the at least one supported tunneling mechanism or protocol and the two DNAIs.

[0067] In step S-503, the second network node receives from the third network node a tunnel response including a selected tunneling mechanism or protocol and the IP tunnel endpoint address. In step S-504, the second network node transmits to the first network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address.

[0068] In some embodiments, the method further comprises determining at the second network node the two DNAIs based on the first tunnel request, particularly wherein determining at the second network node the two DNAIs comprises receiving at the second network node from the first network node the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs).

[0069] In some embodiments, the first or second tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support.

[0070] In some embodiments, the first and / or second tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs) of the EAS.

[0071] In some embodiments, the method further comprises determining at the second network node the two DNAIs based on the first tunnel request.

[0072] In some embodiments, the method further comprises determining at the second network node an SMF supporting the two DNAIs based on the first tunnel request.

[0073] In some embodiments, the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation (GRE) and IP-in-IP tunneling mechanisms.

[0074] In some embodiments, the method further comprises the selection of Tunnel Endpoint Identifiers (TEIDs) for both UL and DL traffic.

[0075] In some embodiments, the local and a central part of the Distributed Network (DN) are disjoint IP networks without direct connectivity.

[0076] In some embodiments, the first network node is an Edge Application Server / Application Function (EAS / AF), the second network node is a Network Exposure Function (NEF), and the third network node is a Session Management Function (SMF).

[0077] Figure 6 is a flowchart illustrating a method performed by the third network node for routing of application traffic between a local and a central part of a Distributed Network, DN.

[0078] In step S-601 , the third network node receives from a second network node a second tunnel request including at least one supported tunneling mechanism or protocol and two DNAIs. In step S-602, the third network node selects one of the at least one supported tunneling mechanism or protocol.

[0079] In step S-603, the third network node determines a first and a second User Plane Function (UPF) as the tunnel endpoints based on the DNAIs and the selected tunneling mechanism or protocol, particularly wherein the first UPF or the second UPF is a UPF in a central part of the DN or a local part of the DN.

[0080] In step S-604, the third network node initiates a N4 Session Establishment procedure with the first UPF, wherein the initiating further comprises receiving at the SMF from the first UPF an N4 Session Establishment Response including a Tunnel Endpoint Identifier (TEID) for uplink traffic of the tunnel, particularly wherein the TEID is selected by the first UPF.

[0081] In step S-605, the third network node initiates a N4 Session Establishment procedure with the second UPF to provide the TEID for uplink traffic of the tunnel and an IP tunnel endpoint address for uplink traffic, particularly wherein the IP tunnel endpoint address is obtained from an UPF or configured in the SMF, and particularly wherein the IP tunnel endpoint address further comprises a port number.

[0082] In step S-606, the third network node transmits to the second network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address.

[0083] In some embodiments, the second tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support.

[0084] In some embodiments, the second tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names (FQDNs) of the EAS.

[0085] In some embodiments, the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation (GRE) and IP-in-IP tunneling mechanisms.

[0086] In some embodiments, the method further comprises the selection of Tunnel Endpoint Identifiers (TEIDs) for both UL and DL traffic.

[0087] In some embodiments, the local and a central part of the Distributed Network (DN) are disjoint IP networks without direct connectivity. In some embodiments, the second network node is a Network Exposure Function (NEF), and the third network node is a Session Management Function (SMF).

[0088] Figure 7 is a block diagram illustrating elements of a mobile network node 700 of a mobile communications network. In some embodiments, the mobile network node 700 is an EAS / AF 113. As shown, the mobile network node may include network interface circuitry 701 (also referred to as a network interface) configured to provide communications with other nodes of the core network and / or the network. The mobile network node may also include a processing circuitry 702 (also referred to as a processor) coupled to the network interface circuitry, and memory circuitry 703 (also referred to as memory) coupled to the processing circuitry. The memory circuitry 703 may include computer readable program code that when executed by the processing circuitry 702 causes the processing circuitry to perform operations according to embodiments disclosed herein. According to other embodiments, processing circuitry 702 may be defined to include memory so that a separate memory circuitry is not required. As discussed herein, operations of the mobile network node may be performed by processing circuitry 702 and / or network interface circuitry 701 . For example, processing circuitry 702 may control network interface circuitry 701 to transmit communications through network interface circuitry 701 to one or more other network nodes and / or to receive communications through network interface circuitry from one or more other network nodes. Moreover, modules may be stored in memory 703, and these modules may provide instructions so that when instructions of a module are executed by processing circuitry 702, processing circuitry 702 performs respective operations (e.g., operations discussed below with respect to Example Embodiments relating to core network nodes).

[0089] Figure 8 is a block diagram illustrating elements of a mobile network node 800 of a mobile communications network. In some embodiments, the mobile network node 800 is a NEF 109. As shown, the mobile network node may include network interface circuitry 801 (also referred to as a network interface) configured to provide communications with other nodes of the core network and / or the network. The mobile network node may also include a processing circuitry 802 (also referred to as a processor) coupled to the network interface circuitry, and memory circuitry 803 (also referred to as memory) coupled to the processing circuitry. The memory circuitry 803 may include computer readable program code that when executed by the processing circuitry 802 causes the processing circuitry to perform operations according to embodiments disclosed herein. According to other embodiments, processing circuitry 802 may be defined to include memory so that a separate memory circuitry is not required. As discussed herein, operations of the mobile network node may be performed by processing circuitry 802 and / or network interface circuitry 801 . For example, processing circuitry 802 may control network interface circuitry 801 to transmit communications through network interface circuitry 801 to one or more other network nodes and / or to receive communications through network interface circuitry from one or more other network nodes. Moreover, modules may be stored in memory 803, and these modules may provide instructions so that when instructions of a module are executed by processing circuitry 802, processing circuitry 802 performs respective operations (e.g., operations discussed below with respect to Example Embodiments relating to core network nodes).

[0090] Figure 9 is a block diagram illustrating elements of a mobile network node 900 of a mobile communications network. In some embodiments, the mobile network node 900 is an SMF 107. As shown, the mobile network node may include network interface circuitry 901 (also referred to as a network interface) configured to provide communications with other nodes of the core network and / or the network. The mobile network node may also include a processing circuitry 902 (also referred to as a processor) coupled to the network interface circuitry, and memory circuitry 903 (also referred to as memory) coupled to the processing circuitry. The memory circuitry 903 may include computer readable program code that when executed by the processing circuitry 902 causes the processing circuitry to perform operations according to embodiments disclosed herein. According to other embodiments, processing circuitry 902 may be defined to include memory so that a separate memory circuitry is not required. As discussed herein, operations of the mobile network node may be performed by processing circuitry 902 and / or network interface circuitry 901 . For example, processing circuitry 902 may control network interface circuitry 901 to transmit communications through network interface circuitry 901 to one or more other network nodes and / or to receive communications through network interface circuitry from one or more other network nodes. Moreover, modules may be stored in memory 903, and these modules may provide instructions so that when instructions of a module are executed by processing circuitry 902, processing circuitry 902 performs respective operations (e.g., operations discussed below with respect to Example Embodiments relating to core network nodes).

[0091] Figure 10 is a block diagram illustrating a virtualization environment 1000 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 1000 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 1000 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an 0-2 interface.

[0092] Applications 1002 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0093] Hardware 1004 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1006 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1008a and 1008b (one or more of which may be generally referred to as VMs 1008), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1006 may present a virtual operating platform that appears like networking hardware to the VMs 1008.

[0094] The VMs 1008 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1006. Different embodiments of the instance of a virtual appliance 1002 may be implemented on one or more of VMs 1008, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0095] In the context of NFV, a VM 1008 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 1008, and that part of hardware 1004 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 1008 on top of the hardware 1004 and corresponds to the application 1002.

[0096] Hardware 1004 may be implemented in a standalone network node with generic or specific components. Hardware 1004 may implement some functions via virtualization. Alternatively, hardware 1004 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 1010, which, among others, oversees lifecycle management of applications 1002. In some embodiments, hardware 1004 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1012 which may alternatively be used for communication between hardware nodes and radio units.

[0097] Embodiments within the scope of the present invention may also include computer-readable media for carrying or having computer-executable instructions or data structures stored thereon. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such tangible computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions or data structures. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or combination thereof) to a computer, the computer properly views the connection as a computer-readable medium. Thus, any such connection is properly termed a computer- readable medium. Combinations of the above should also be included within the scope of the tangible computer-readable media.

[0098] Computer-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Computer-executable instructions also include program modules that are executed by computers in standalone or network environments. Generally, program modules include routines, programs, objects, components, and data structures that perform particular tasks or implement particular abstract data types. Computer executable instructions, associated data structures, and program modules represent examples of the program code means for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represent examples of corresponding acts for implementing the functions described in such steps.

[0099] Those of skill in the art will appreciate that other embodiments of the invention may be practiced in network computing environments with many types of computer system configurations, including personal computers, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like. Embodiments may also be practiced in distributed computing environments where tasks are performed by local and remote processing devices that are linked (either by hardwired links, wireless links, or by a combination thereof) through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.

[0100] Communication at various stages of the described system can be performed through a local area network, a token ring network, the Internet, a corporate intranet, 802.11 series wireless signals, fiber-optic network, radio or microwave transmission, etc. Although the underlying communication technology may change, the fundamental principles described herein are still applicable.

[0101] The various embodiments described above are provided by way of illustration only and should not be construed to limit the invention. For example, the principles herein may be applied to any remotely controlled device. Further, those of skill in the art will recognize that communication between the remote the remotely controlled device need not be limited to communication over a local area network but can include communication over infrared channels, Bluetooth or any other suitable communication interface. Those skilled in the art will readily recognize various modifications and changes that may be made to the present invention without following the example embodiments and applications illustrated and described herein, and without departing from the scope of the present disclosure.

[0102] The terminology used herein is for the purpose of describing various embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "includes," "including," "comprises," and "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, or components, and combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, or components, and combinations thereof. Further, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to ""a / an / the element, apparatus, component, means, module, step, etc."" are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Claims

CLAIMS1 . A method for routing of application traffic between a local and a central part of a Distributed Network, DN, the method comprising: transmitting (S-401) from a first network node to a second network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers, DNAIs, the first tunnel request including at least one supported tunneling mechanism or protocol; transmitting (S-502) from the second network node to a third network node a second tunnel request including the at least one supported tunneling mechanism or protocol and the two DNAIs; selecting (S-602) at the third network node one of the at least one supported tunneling mechanism or protocol; determining (S-603) at the third network node a first and a second User Plane Function, UPF, as the tunnel endpoints based on the DNAIs and the selected tunneling mechanism or protocol, particularly wherein the first UPF or the second UPF is a UPF in a central part of the DN or a local part of the DN; initiating (S-604) at the third network node a N4 Session Establishment procedure with the first UPF, wherein the initiating further comprises receiving at the SMF from the first UPF an N4 Session Establishment Response including a Tunnel Endpoint Identifier, TEID, for uplink traffic of the tunnel, particularly wherein the TEID is selected by the first UPF; initiating (S-605) at the third network node a N4 Session Establishment procedure with the second UPF to provide the TEID for uplink traffic of the tunnel and an IP tunnel endpoint address for uplink traffic, particularly wherein the IP tunnel endpoint address is obtained from an UPF or configured in the SMF, and particularly wherein the IP tunnel endpoint address further comprises a port number; transmitting (S-606) from the third network node to the second network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address; andtransmitting (S-504) from the second network node to the first network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address.

2. The method of claim 1 , wherein the method further comprises determining at the second network node the two DNAIs based on the first tunnel request, particularly wherein determining at the second network node the two DNAIs comprises receiving at the second network node from the first network node the two DNAIs, IP address ranges or Fully Qualified Domain Names, FQDNs.

3. The method of any one of claims from claim 1 to claim 2, wherein the first or second tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support.

4. The method of any one of claims from claim 1 to claim 3, wherein the first and / or second tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names, FQDNs, of the EAS.

5. The method of any one of claims from claim 1 to claim 4, wherein the method further comprises determining at the second network node the two DNAIs based on the first tunnel request.

6. The method of any one of claims from claim 1 to claim 5, wherein the method further comprises determining at the second network node an SMF supporting the two DNAIs based on the first tunnel request.

7. The method of any one of claims from claim 1 to claim 6, wherein the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation, GRE, and IP-in-IP tunneling mechanisms.

8. The method of any one of claims from claim 1 to claim 7, wherein the method further comprises the selection of Tunnel Endpoint Identifiers, TEIDs, for both UL and DL traffic.

9. The method of any one of claims from claim 1 to claim 8, wherein the local and a central part of the Distributed Network, DN, are disjoint IP networks without direct connectivity.

10. The method of any one of claims from claim 1 to claim 9, wherein the first network node is an Edge Application Server / Application Function, EAS / AF, the second network nodeis a Network Exposure Function, NEF, and the third network node is a Session Management Function, SMF.

11. A method performed by a first network node for routing of application traffic between a local and a central part of a Distributed Network, DN, the method comprising: transmitting (S-401) from a first network node to a second network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers, DNAIs, the first tunnel request including at least one supported tunneling mechanism or protocol; and receiving (S-402) at the first network node from the second network node a tunnel response including a selected tunneling mechanism or protocol and the IP tunnel endpoint address.

12. The method of claim 11 , wherein the first tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support.

13. The method of any one of claims from claim 11 to claim 12, wherein the first tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names, FQDNs, of the EAS.

14. The method of any one of claims from claim 11 to claim 13, wherein the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation, GRE, and IP-in-IP tunneling mechanisms.

15. The method of any one of claims from claim 11 to claim 14, wherein the local and a central part of the Distributed Network, DN, are disjoint IP networks without direct connectivity.

16. The method of any one of claims from claim 11 to claim 15, wherein the first network node is an Edge Application Server / Application Function, EAS / AF, and the second network node is a Network Exposure Function, NEF.

17. A method performed by a second network node for routing of application traffic between a local and a central part of a Distributed Network, DN, the method comprising: receiving (S-501) at a second network node from a first network node a first tunnel request to set up a tunnel between two Distributed Network Address Identifiers, DNAIs, the first tunnel request including at least one supported tunneling mechanism or protocol;transmitting (S-502) from the second network node to a third network node a second tunnel request including the at least one supported tunneling mechanism or protocol and the two DNAIs; receiving (S-503) at the second network node from the third network node a tunnel response including a selected tunneling mechanism or protocol and the IP tunnel endpoint address; and transmitting (S-504) from the second network node to the first network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address.

18. The method of claim 17, wherein the method further comprises determining at the second network node the two DNAIs based on the first tunnel request, particularly wherein determining at the second network node the two DNAIs comprises receiving at the second network node from the first network node the two DNAIs, IP address ranges or Fully Qualified Domain Names, FQDNs.

19. The method of any one of claims from claim 17 to claim 18, wherein the first or second tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support.

20. The method of any one of claims from claim 17 to claim 19, wherein the first and / or second tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names, FQDNs, of the EAS.21 . The method of any one of claims from claim 17 to claim 20, wherein the method further comprises determining at the second network node the two DNAIs based on the first tunnel request.

22. The method of any one of claims from claim 17 to claim 21 , wherein the method further comprises determining at the second network node an SMF supporting the two DNAIs based on the first tunnel request.

23. The method of any one of claims from claim 17 to claim 22, wherein the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation, GRE, and IP-in-IP tunneling mechanisms.

24. The method of any one of claims from claim 17 to claim 23, wherein the method further comprises the selection of Tunnel Endpoint Identifiers, TEIDs, for both UL and DL traffic.

25. The method of any one of claims from claim 17 to claim 24, wherein the local and a central part of the Distributed Network, DN, are disjoint IP networks without direct connectivity.

26. The method of any one of claims from claim 17 to claim 25, wherein the first network node is an Edge Application Server / Application Function, EAS / AF, the second network node is a Network Exposure Function, NEF, and the third network node is a Session Management Function, SMF.

27. A method performed by a third network node for routing of application traffic between a local and a central part of a Distributed Network, DN, the method comprising: receiving (S-601) at a third network node from a second network node a second tunnel request including at least one supported tunneling mechanism or protocol and two DNAIs; selecting (S-602) at the third network node one of the at least one supported tunneling mechanism or protocol; determining (S-603) at the third network node a first and a second User Plane Function, UPF, as the tunnel endpoints based on the DNAIs and the selected tunneling mechanism or protocol, particularly wherein the first UPF or the second UPF is a UPF in a central part of the DN or a local part of the DN; initiating (S-604) at the third network node a N4 Session Establishment procedure with the first UPF, wherein the initiating further comprises receiving at the SMF from the first UPF an N4 Session Establishment Response including a Tunnel Endpoint Identifier, TEID, for uplink traffic of the tunnel, particularly wherein the TEID is selected by the first UPF; initiating (S-605) at the third network node a N4 Session Establishment procedure with the second UPF to provide the TEID for uplink traffic of the tunnel and an IP tunnel endpoint address for uplink traffic, particularly wherein the IP tunnel endpoint address is obtained from an UPF or configured in the SMF, and particularly wherein the IP tunnel endpoint address further comprises a port number; andtransmitting (S-606) from the third network node to the second network node a tunnel response including the selected tunneling mechanism or protocol and the IP tunnel endpoint address.

28. The method of claim 27, wherein the second tunnel request further include any one of: tunnel address information, such as tunnel address of the first network node, optional parameters, a key value, and indication of Multiplexed Application Substrate over QUIC Encryption, MASQUE, support.

29. The method of any one of claims from claim 27 to claim 28, wherein the second tunnel request further comprises the two DNAIs, IP address ranges or Fully Qualified Domain Names, FQDNs, of the EAS.

30. The method of any one of claims from claim 27 to claim 29, wherein the at least one supported tunneling mechanism comprises any one of Generic Routing Encapsulation, GRE, and IP-in-IP tunneling mechanisms.31 . The method of any one of claims from claim 27 to claim 30, wherein the method further comprises the selection of Tunnel Endpoint Identifiers, TEIDs, for both UL and DL traffic.

32. The method of any one of claims from claim 27 to claim 31 , wherein the local and a central part of the Distributed Network, DN, are disjoint IP networks without direct connectivity.

33. The method of any one of claims from claim 27 to claim 32, wherein the second network node is a Network Exposure Function, NEF, and the third network node is a Session Management Function, SMF.

34. Apparatus for routing of application traffic between a local and a central part of a Distributed Network, DN, the apparatus comprising a processor and a memory, the memory containing instructions executable by the processor such that the apparatus is operable to perform the method of any one of claims from claim 11 to claim 16.

35. Apparatus for routing of application traffic between a local and a central part of a Distributed Network, DN, the apparatus comprising a processor and a memory, the memory containing instructions executable by the processor such that the apparatus is operable to perform the method of any one of claims from claim 17 to claim 26.

36. Apparatus for routing of application traffic between a local and a central part of a Distributed Network, DN, the apparatus comprising a processor and a memory, the memory containing instructions executable by the processor such that the apparatus is operable to perform the method of any one of claims from claim 27 to claim 33.

37. A system comprising an apparatus as claimed in claim 34, an apparatus as claimed in claim 35, and an apparatus as claimed in claim 36.

38. A computer-implemented system comprising one or more processors and one or more computer storage media storing computer-usable instructions that, when used by the one or more processors, cause the one or more processors to perform a method according to any one of claims from claim 11 to claim 33.

39. A computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to perform a method according to any of claims from claim 11 to claim 33.

40. A computer program product, embodied on a non-transitory machine-readable medium, comprising instructions which are executable by a processor, causing the processor to perform the method according to any of claims from claim 11 to claim 33.

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