WO2019015755A1

WO2019015755A1 - Methods and nodes for providing or selecting a user traffic node

Info

Publication number: WO2019015755A1
Application number: PCT/EP2017/068301
Authority: WO
Inventors: Santiago GALLEGO RODRIGO; Yixin Chen; Jorge GARCIA LLORENTE
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2017-07-20
Filing date: 2017-07-20
Publication date: 2019-01-24

Abstract

A method and a policy node(110) for providing a set of indications identifying a set of user traffic nodes as well as a method and a mobility management node (120) for selecting a user traffic node from a set of user traffic nodes are disclosed. The policy node (110)receives(A020), from said each user traffic node (130-132), respective information relating to an operating condition of said each user traffic node (130-132). The policy node (110)determines (A030) a respective weight based on said respective information for said each user traffic node (130-132). The mobility management node (120)receives(A050), from the policy node (110),the set of indications identifying the set of user traffic nodes (130-132)and the set of respective weights for each user traffic node (130-132).The mobility management node (120) selects (A060) the user traffic node (130-132)based on the set of indications identifying the set of user traffic nodes (130-132)and the set of respective weights. The mobility management node (120) transmits(A070), to the selected user traffic node (130-132), a session establishment request. Corresponding computer programs and computer program carriers are also disclosed.

Description

METHODS AND NODES FOR PROVIDING OR

SELECTING A USER TRAFFIC NODE

TECHNICAL FIELD

Embodiments herein relate to wireless communication networks, such as cellular networks, telecommunication networks or the like. In particular, a method and a policy node for providing a set of indications identifying a set of user traffic nodes as well as a method and a mobility management node for selecting a user traffic node from a set of user traffic nodes are disclosed. Corresponding computer programs and computer program carriers are also disclosed.

BACKGROUND

In a telecommunication system, such as Long Term Evolution Evolved Packet Core (LTE EPC), a function called Policy and Charging Rules Function (PCRF) is responsible for handling policy control decisions and flow based charging control functionalities in the telecommunication system. The PCRF provides network and gating control, and manages the flow based charging. In some proprietary implementations, a so called Diameter Smp-interface is used by the PCRF to instruct a Mobility

Management Entity (MME) to select a Packet Data Network Gateway (PDN-GW) for a User Equipment (UE), for example when the UE attaches to the telecommunication system.

With existing solutions, a single or multiple PDN-GWs can be provided, by the PCRF, to the MME.

When the PCRF does not provide any PDN-GW, the MME is able to select the

PDN-GW by use of an Access Point Name (APN) resolving procedure according to Third Generation Partnership Project (3GPP) specifications. Once the APN is resolved, the PDN-GW selection can be dynamic or static.

For dynamic PDN-GW selection, the MME can query a DNS server, which can provide weights for each of the PDN-GWs that the MME queries. These weights are static, in the sense that they are the same regardless the PDN-GW conditions and network conditions, and the same weights are provided for all subscribers.

For static PDN-GW selection, the PDN-GW can be defined in the Home Subscriber Server (HSS) or locally configured in MME. In the first case no weight is available. In the latter, only a static weight can be defined.

Hence, according to known manners, when the UE attaches to the

telecommunication network or requests PDN connectivity, the MME can ask for the PCRF to provide a PDN-GW for the UE. The PCRF selects the PDN-GW by use of information available via the Smp-interface and by use of PCRF subscription based policies, for example Access Point Name (APN), User Location Information, International Mobile Subscriber Identity (IMSI), International Mobile Equipment Identity (IMEI), Subscriber group, Time of Day and the like.

Additionally, when introducing one or more new PDN-GWs in a network dynamically, which can be a typical scenario for Virtual Network Functions (VNFs), said one or more PDN-GWs are initially not handling any user equipments, i.e. not handling any PDN connections or the like. Therefore, time until the newly introduced and previously installed PDN-GWs are evenly loaded may be unnecessarily high.

SUMMARY

An object may thus be how to improve selection of gateways, such as a PDN- GW, e.g. during an initial attach or PDN connectivity procedure, in a telecommunication network e.g. of the above mentioned kind.

According to an aspect, the object is achieved by a method, performed by a policy node, for providing a set of indications identifying a set of user traffic nodes. The policy node manages the set of user traffic nodes according to one or more policies for at least one of subscription and charging. Each user traffic node of the set is capable of forwarding user traffic between a network and a wireless device. The user traffic is assigned to a user traffic node of the set by a mobility management node for managing mobility of the wireless device. The policy node receives, from said each user traffic node, respective information relating to an operating condition of said each user traffic node. The policy node determines a respective weight based on said respective information for said each user traffic node, wherein a set of respective weights comprises each respective weight for said each user traffic node. The policy node transmits, to the mobility management node for attaching the user traffic to one of the user traffic nodes of the set, the set of indications identifying the set of user traffic nodes and the set of respective weights. According to another aspect, the object is achieved by a policy node configured for providing a set of indications identifying a set of user traffic nodes. The policy node manages the set of user traffic nodes according to one or more policies for at least one of subscription and charging. Each user traffic node of the set is capable of forwarding user traffic between a network and a wireless device. The user traffic is assigned to a user traffic node of the set by a mobility management node for managing mobility of the wireless device. The policy node is configured for receiving, from said each user traffic node, respective information relating to an operating condition of said each user traffic node. The policy node is further configured for determining a respective weight based on said respective information for said each user traffic node. A set of respective weights comprises each respective weight for said each user traffic node. Moreover, the policy node is configured for transmitting, to the mobility management node for attaching the user traffic to one of the user traffic nodes of the set, the set of indications identifying the set of user traffic nodes and the set of respective weights.

According to a further aspect, the object is achieved by a method, performed by a mobility management node, for selecting a user traffic node from a set of user traffic nodes. Each user traffic node of the set is capable of forwarding user traffic between a network and a wireless device. The mobility management node receives, from a policy node for managing the set of user traffic nodes according to one or more policies for at least one of subscription and charging, a set of indications identifying the set of user traffic nodes and a set of respective weights for each user traffic node of the set of user traffic nodes. The mobility management node selects the user traffic node based on the set of indications identifying the set of user traffic nodes and the set of respective weights. The mobility management node transmits, to the selected user traffic node, a session establishment request.

According to yet another aspect, the object is achieved by a mobility

management node configured for selecting a user traffic node from a set of user traffic nodes. Each user traffic node of the set is capable of forwarding user traffic between a network and a wireless device. The mobility management node is configured for receiving, from a policy node for managing the set of user traffic nodes according to one or more policies for at least one of subscription and charging, a set of indications identifying the set of user traffic nodes and a set of respective weights for each user traffic node of the set of user traffic nodes. The mobility management node is further configured for selecting the user traffic node based on the set of indications identifying the set of user traffic nodes and the set of respective weights. Moreover, the mobility management node is configured for transmitting, to the selected user traffic node, a session establishment request.

According to further aspects, the object is achieved by computer programs and computer program carriers corresponding to the aspects above.

Thanks to that the policy node receives, from said each user traffic node, the respective information relating to the operating condition of said each user traffic node, the policy node is able to determine the respective weight based on said respective information for said each user traffic node. Hence, the policy node determines the respective weight for said each user traffic node, wherein the respective weight may reflect the operating condition, such as memory usage, processor usage, number of PDN connections, Quality of Experience (QoE), etc., at said each user traffic node.

Next, in order to make the mobility management node aware of the available user traffic nodes, the policy node transmits, to the mobility management node, the set of indications identifying the set of user traffic nodes and the set of respective weights.

Upon receiving the set of indications, the mobility management node selects the user traffic node based on the set of indications and the set of respective weights. In this manner, the mobility management node may take into account the operating conditions on which the set of respective weights are based. Subsequently, e.g. in order to provide a PDN connection to the wireless device, the mobility management node transmits, to the selected user traffic node, a session establishment request.

An advantage is that the embodiments herein enable the mobility management node to take dynamic operating conditions into account when selecting the user traffic node.

Another advantage may, for at least some embodiments, be that the load balancing, among available user traffic nodes, may be achieved by considering dynamic and/or current operating conditions. In particular embodiments, the policy node may be a node implementing a Policy and Charging Rules Function, PCRF, or a Policy Control Function, PCF; the mobility management node may be a node implementing a Mobility Management Entity, MME, or an access and mobility management function, AMF; and the user traffic node may be a node implementing a packet data network gateway, PDN-GW, or a user part function, UPF, or a session management function, SMF.

BRIEF DESCRIPTION OF THE DRAWINGS

The various aspects of embodiments disclosed herein, including particular features and advantages thereof, will be readily understood from the following detailed description and the accompanying drawings, in which:

Figure 1 is a schematic overview of an exemplifying system in which

embodiments herein may be implemented,

Figure 2 is a combined signaling and flowchart illustrating the methods herein, Figure 3 is a combined signaling and flowchart illustrating some embodiments of the methods herein,

Figure 4 is a combined signaling and flowchart illustrating some further embodiments of the methods herein,

Figure 5 is a flowchart illustrating embodiments of the method in the policy node, Figure 6 is a block diagram illustrating embodiments of the policy node,

Figure 7 is a flowchart illustrating embodiments of the method in the mobility management node, and

Figure 8 is a block diagram illustrating embodiments of the mobility management node.

DETAILED DESCRIPTION

Throughout the following description similar reference numerals have been used to denote similar features, such as nodes, actions, modules, circuits, parts, items, elements, units or the like, when applicable. In the Figures, features that appear in some embodiments are indicated by dashed lines.

Figure 1 depicts an exemplifying telecommunication network 100 in which embodiments herein may be implemented. In this example, the telecommunication network 100 is a Long Term Evolution (LTE) network. In other examples, the telecommunication network 100 may be a Universal Mobile Telecommunication System (UMTS), a Worldwide Interoperability for Microwave Access (WiMAX) network, a Global System for Mobile communication (GSM) network or the like. The telecommunication network 100 may be said to comprise a policy node 1 10, such as PCRF, Service Aware Policy Controller (SAPC), a Policy Control Function (PCF) or the like.

Furthermore, the telecommunication network 100 may be said comprise a mobility management node 120, such as an Mobility Management Entity (MME), an Access and Mobility Management Function (AMF) or the like. An interface between the policy node 1 10 and the mobility management node 120 may be referred to as Smp- interface.

Additionally, the telecommunication network 100 may be said comprise a set of user traffic nodes 130-132, such as one or more PDN-GWs (PGWs), User Part

Functions (UPFs), Session Management Functions (SMFs) or the like. Interfaces between each of the user traffic nodes 130-132 and the policy node 1 10 may be referred to as Gx-interfaces.

Each of the user traffic nodes 130-132 may be connected to a Serving Gateway (SGW) 140, which is managed by the mobility management node 120.

Moreover, the SGW 140 may be connected to a radio network node 150, such as a base station, a radio base station, a relay node, a repeater, a radio network controller, an evolved Node B (eNB) or the like.

Each of the user traffic nodes 130-132 may forward traffic between a network 101 and e.g. a wireless device 160, typically via the SGW 140 and the radio network node 150. The network 101 may be external with respect to the telecommunication network 100, i.e. the network 101 may be not operated by an operator that manages the telecommunication network 100.

The mobility management node 120 may further be connected to a DNS server 170 and/or a Home Subscriber System (HSS) 180 according to know manners.

As illustrated, to the lower right of the radio network node 150, traffic to/from the

SGW 140 may take different paths depending on scenario.

As used herein, the term "wireless device" may refer to a user equipment, a wireless communication device, a machine-to-machine (M2M) device, a mobile phone, a cellular phone, a Personal Digital Assistant (PDA) equipped with radio communication capabilities, a smartphone, a laptop or personal computer (PC) equipped with an internal or external mobile broadband modem, a tablet PC with radio communication capabilities, a portable electronic radio communication device, a sensor device equipped with radio communication capabilities or the like. The sensor device may detect any kind of metric, such as wind, temperature, air pressure, humidity, light, electricity, sound, images etc. The term "user" may indirectly refer to the wireless device. Sometimes, the term "user" may be used to refer to the user equipment or the like as above. It shall be understood that the user may not necessarily involve a human user. The term "user" may also refer to a machine, a software component or the like using certain functions, methods and similar.

Figure 2 illustrates exemplifying methods according to embodiments herein when implemented in the telecommunication network 100 of Figure 1. The exemplifying methods are performed by the policy node 110 and the mobility management node 120, respectively.

Hence, the policy node 1 10 performs a method for providing a set of indications identifying a set of user traffic nodes 130-132 and the mobility management node 120 performs a method for selecting a user traffic node 130-132 from a set of user traffic nodes 130-132.

The policy node 1 10 manages the set of user traffic nodes 130-132 according to one or more policies for at least one of subscription and charging. Each user traffic node 130-132 of the set is capable of forwarding user traffic between the network 101 and the wireless device 160. The user traffic is assigned to the user traffic node 130-132 of the set by the mobility management node 120 for managing mobility of the wireless device 160.

The method may be performed during an attach procedure, or similar procedure, for the telecommunication network 100, which for example allow the wireless device 160 to obtain a PDN connection towards the network 101 . Again, it may here be noted that the telecommunication network 100 may comprise the policy node 1 10, the mobility management node 120, one or more user traffic nodes 130-132, the wireless device 160 etc. as shown in Figure 1 , but the telecommunication network 100 may not comprise the network 101. One or more of the following actions may be performed in any suitable order.

Action A010

Each of the user traffic nodes 130-132 may send respective information relating to an operating condition of each user traffic node 130-132. The operating condition for a first user traffic node 130 may typically be different from the operating condition for a second user traffic node 131 , i.e. there is a respective operating condition for each user traffic node 130-132 which may be different or the same as compared to another operating condition of any other user traffic node.

The operating condition of said each user traffic node 130-132 may refer to at least one of:

utilization of a resource of said each user traffic node 130-132,

a parameter relating to at least one of a number of sessions, such as Internet Protocol Connectivity Access Network (IP-CAN) sessions, handled by said each user traffic node 130-132, a Quality of Experience, a latency, a throughput, a packet loss rate, a jitter for each said user traffic node 130-132, and

- the like.

The resource may comprise at least one of processing power and memory capacity.

Each of the user traffic nodes 130-132 may send the respective information regularly or irregularly.

Action A020

Subsequent to action A010, the policy node 1 10 receives, from said each user traffic node 130-132, the respective information relating to the operating condition of said each user traffic node 130-132, e.g. relating to the respective operating condition of said each user traffic node 130-132.

In action A010 and A020, the respective information relating to the operating condition may be conveyed over an interface referred to as Gx-interface or the like.

Action A030

Once the respective information has been received by the policy node 1 10, the policy node 1 10 determines a respective weight based on said respective information for said each user traffic node 130-132. A set of respective weights comprises each respective weight for said each user traffic node 130-132.

Action A040

In order to make the mobility management node 120 aware of the user traffic nodes 130-132 and the set of respective weights, the policy node 1 10 transmits, to the mobility management node 120 for attaching the user traffic to one of the user traffic nodes 130-132 of the set, the set of indications identifying the set of user traffic nodes 130-132 and the set of respective weights.

The user traffic may originate from the wireless device 160, or be destined to the wireless device 160, which attaches to the telecommunication network 100 in order to send/receive data.

Action A050

Following action A040, the mobility management node 120 receives, from the policy node 1 10 for managing the set of user traffic nodes 130-132 according to one or more policies for at least one of subscription and charging, the set of indications identifying the set of user traffic nodes 130-132 and the set of respective weights for each user traffic node 130-132 of the set of user traffic nodes 130-132.

In this manner, the mobility management node 120 is made aware of the set of indications identifying the set of user traffic nodes 130-132 and the set of respective weights for each user traffic node 130-132 of the set of user traffic nodes 130-132.

In action A040 and A050, the set of indications identifying the set of user traffic nodes 130-132 and the set of respective weights may be conveyed over an interface referred to as Smp-interface or the like.

Action A060

Subsequent to action A050, the mobility management node 120 selects the user traffic node 130-132 based on the set of indications identifying the set of user traffic nodes 130-132 and the set of respective weights.

As an example, the mobility management node 120 may select the user traffic node 130-132 randomly or quasi randomly while taking the set of respective weights into account, wherein a respective weight may be directly or inversely related to a probability of selecting the user traffic node 130-132 that corresponds to said respective weight. Action A070

When action A060 has been completed, the mobility management node 120 transmits, to the selected user traffic node 130-132, a session establishment request. Thanks to the session establishment request, the mobility management node 120 assigns a user traffic node to handle the user traffic between the network 101 and the wireless device 160.

In view of the above, the embodiments herein provides a way of passing information about the operating conditions of the user traffic nodes, such as an PDN- GW, to the policy node 1 10, such as a PCRF. The operating conditions may be dynamic in that the operating conditions change over time due to e.g. number of sessions, CPU usage, memory usage, subscriber QoE, etc. The policy node 1 10 can then use this information to suggest to the mobility management node 120 one or more user traffic nodes 130-132 to be used for new attachments of wireless devices.

Furthermore, the policy node 1 10 provides to the mobility management node 120 a respective weight for each user traffic node 130-132, from which the mobility management node 120 may deduce a suitable user traffic node to be used for a current attachment.

Several algorithms based on the weights can be used by the mobility management node 120 to deduce, or select, the user traffic node to be used for the current attachment. Some examples will be given below with reference to action 406 of Figure 4. It shall be understood that the embodiments herein may also be implemented in a so called 5^th generation (5G) network. In such case, the policy node 1 10, such as a Policy Control Function (PCF) may collect periodically, or non-periodically, resource utilization data from the user traffic nodes, such as User Part Functions (UPFs), e.g. via an SMF over an NG7-interface. Then, the PCF may apply a UPF selection mechanism including weights for each UPF, and pass that information on to the mobility management node 120, such as an AMF, over an NG15 interface. Accordingly, information exchanged over Gx-interface applies to the NG7-interface, and information exchanged over Smp-interface applies to NG15-interface.

Hence, in various embodiments herein, the policy node 1 10 may implement a Policy and Charging Rules Function, PCRF, or a Policy Control Function, PCF, or the like. The mobility management node 120 may implement a Mobility Management Entity, MME, or an access and mobility management function, AMF, or the like. The user traffic node 130-132 may implement a packet data network gateway, PDN-GW, a user part function, UPF, or a session management function, SMF, or the like.

Thus, at least some embodiments provides a solution that may be extended to the dynamic conditions of the control and user plane resources in virtual operating networks based on 5G networks' slicing concepts. Thanks to at least some embodiments herein, the operator is allowed to flexibly adapt usage of the user traffic nodes to current operating conditions at the user traffic nodes by assigning new wireless devices, i.e. wireless device not already attached to the telecommunication network, to one of the most suitable user traffic nodes, e.g. one that is among the least loaded in terms of memory and/or processing usage or the like as mentioned above.

At least some embodiments herein allows an operator of the telecommunication network, i.e. a service network, to reduce operation costs while keeping a balanced load among available user traffic nodes 130-132, e.g. since no manual intervention is required in order to find a suitable user traffic node to serve a wireless device that is attaching to the telecommunication network.

Moreover, with some embodiments, load among user traffic nodes converges to be evenly, or nearly evenly, distributed among them automatically when new user traffic nodes are added to the network, or when user traffic nodes are removed from it, by assigning more weight to the user traffic nodes that have more available resources or have a higher capacity, i.e. are less loaded.

As will be described in the following, the embodiments herein may be

implemented as two parts.

A first part relates dynamic collection of information about status of the user traffic nodes 130-132 in the telecommunication network 100, in order to obtain information about available resources in the user traffic nodes, and to provide that information to the policy node 1 10.

A second part relates to assessment of resource usage for the selected one or more user traffic nodes and to calculation of the respective weights, Furthermore, the second part relates to how to provide the respective weights and indications, or identifiers, of the associated user traffic nodes to the mobility management node 120. In turn, the mobility management node 120 may then use the received information to determine the user traffic node to be used when continuing with an attachment of a wireless device.

The first part is described with reference to Figure 3 and the second part is described with reference to Figure 4 below. The messages of Figure 3 and/or 4 will be further described after the description of Figure 4. According to Figure 3, the policy node 1 10 is exemplified by a PCRF and a user traffic node 130-132 is exemplified by a PDN-GW.

One or more of the following actions may be performed.

Action 301

The PDN-GW commences with collection of information relating to the operational conditions for itself periodically or non-periodically. A period for the collection may preferably be short enough so that the collected information is current enough when used e.g. by the mobility management node 120, but not too short so that the collection may impact user traffic. Collecting this data initially every 10 seconds may be a suitable for some use cases, but the period for collection may be configurable to adapt to different networks and operators.

Action 302

The PDN-GW collects information relating to the operational conditions for itself. As already mentioned, the information may include:

a current number of sessions in the PDN-GW, e.g. as a percentage of the maximum capacity,

a current CPU usage in the PDN-GW, e.g. as a percentage of the maximum capacity,

a current memory usage in the PDN-GW, e.g. as a percentage of the maximum capacity,

a current estimated QoE for subscribers, i.e. wireless devices, attached using the PDN-GW, based on packet losses, latency, jitter, throughput, etc, and

the like. Once the information relating to the operational conditions is collected in the PDN-GW, it may be sent to the PCRF, for example via the Gx interface. Some options are:

using a PUSH mechanism, where the PDN-GW informs periodically to the PCRF about the resource utilization

using a PULL mechanism, where it's the PCRF the one responsible for asking the PDN-GW about its resource utilization

Action 303

Thus, in order to inform the PCRF about the information relating to the operational conditions, the PDN-GW may send a Credit Control Request (CCR)-Update (U) message, configured as described below with reference to an example

implementation, to the PCRF. The CCR-U message may include information about resource utilization, i.e. the information relating to operational conditions.

Action 304

The PCRF collects information about resource utilization for one, some or all PDN-GWs. When new samples of the information about resource utilization are received from a PDN-GW for which the PCRF already has previous resource utilization, the new sample may overrides the previous sample, the new sample is fed to a moving average filter or similar actions may be taken.

Action 305

Once the PCRF has correctly received the information about resource utilization from the PDN-GW, the PCRF may send a Credit Control Answer (CCA) message to the PDN-GW that provided the information about its resource utilization.

In the first part above, the information about operational conditions is obtained in any suitable manner.

Note that actions according to Figure 3 may be performed by all the PDN-GWs that may be selected by the PCRF.

According to Figure 4, the wireless device 160 is exemplified by a UE, the mobility management node 120 is exemplified by an MME, the policy node 1 10 is exemplified by a PCRF, a user traffic node 130-132 is exemplified by a PDN-GW.

Figure 4 describes an exemplifying way of calculating and providing a weighted list of PDN-GWs from the PCRF to the MME over an Smp-interface.

One or more of the following actions may be performed.

Action 401

The UE sends an attach request to the MME, e.g. via an access network e.g. represented by the radio network node 150 in Figure 1. Action 402

The MME sends a CCR-lnitial (I) message to the PCRF in order to request a list of PDN-GWs.

Action 403

The PCRF finds, or selects, a set of PDN-GW which can provide a PDN connection for a new subscriber, i.e. UE.

Action 404

Since the resource utilization, i.e. a current resource utilization, for the PDN- GWs is known by the PCRF according to the first part above, this information may be used when the UE is attaching to the telecommunication network.

Thus, the PCRF calculates a respective weight for each of the PDN-GWs. Several algorithms can be used to determine the actual weights sent to the MME, but all may take into account that the weight may be directly or inversely proportional to the resource utilization.

For example, if using a linear inverse algorithm:

Thus, the higher the utilization the lower the probability to select that particular PDN-GW.

As can be seen, the algorithm gives the highest weight to the least loaded PDN- GW, and the lowest weight to the most loaded PDN-GW, producing that the less loaded PDN-GWs are selected with a higher probability. This leads to a long term convergence, where the load in the PDN-GWs will be approximately balanced.

The value for the weight sent in an Smp CCA Initial message for the PDN-GW may be the value defined in the "Weight" row. Given as an input the resource utilization for each PDN-GW (η), the weight (w,) for each PDN-GW can be formulated as:

With this, the probability for each PDN-GW to be selected (P,) can be formulated as:

Other algorithms may also be used, which may make convergence faster, i.e. make load, or resource utilization, on PGWs to be evenly, or nearly evenly, distributed among the available PGWs.

Action 405

The PCRF may send a CCA-I message to the MME. The CCA-I message may include the set of indications identifying the PDN-GWs and the respective weight for each of these. E.g. the CCA-I message may include MIP6-Agent-lnfo, i.e. the weighted list of PDN-GWs.

Action 406

When the MME receives the weighted list of PDN-GWs, the MME may use the weights to determine the PDN-GW for the attachment to continue based on probabilistic data, i.e. the weighted list.

As an example, the MME may generate a random number between 0 and the sum of all the weights. Then, the MME may map the random number to the

corresponding PDN-GW which is to be selected.

As another example, the MME may map all the weights for the PDN-GWs to a value so that the sum of all the weights is 1000. Then, when the PDN-GW selection decision has to be made, the MME may retrieve the current system time in milliseconds, and keep only the current milliseconds, and then map it to one of the PDN-GWs, i.e. the one to be selected. Action 407

The MME sends a Create Session Request to the selected PDN-GW. Action 408

The PDN-GW sends a Create Session Response message to the MME. This message may include the IP address of the UE.

Action 409

The MME sends a CCR-U message to the PCRF. This message may include an identification of the selected PDN-GW and the IP address of the UE.

Action 410

Accordingly, the PCRF may send a CCA-U message in response to the CCR-U message. In the following, an exemplifying implementation over the Gx-interface and Smp- interface is described.

Gx Credit-Control Request Update (CCR-U) message

The Gx CCR Update message is sent from the PDN-GW to the PCRF according to Figure 3. According to at least some embodiments herein, this message may be extended to support reporting of information relating to the operational conditions, aka the resource utilization, from the PDN-GW:

<CC-Request> ::= < Diameter Header: 272, REQ, PXY >

[^■■■ ]

*[ Resource-Utilization I

Such Attribute Value Pairs (AVPs) may be sent in a dedicated message from the PDN-GW to the PCRF if there's no traffic between them or piggybacked in another CCR- U message in order to avoid additional signalling.

Note that the resource utilization is reported per node at node level.

Resource-Utilization AVP

This AVP is added to the Gx CCR-U message(s) in order to provide details about the utilization of specific resources in the PDN-GW. It's a Grouped AVP containing information about which resource is reported and its utilization:

Resource-Utilization ::= < AVP Header: XXX >

{ Resource-Type }

{ Resource-Value }

[ Resource-Max-Value ]

Resource-Type A VP

This AVP is of type Enumerated and indicates the type of resource whose utilization is being reported. The following values may be supported:

- NUMBER_OF_SESSIONS (0)

o Indicates that the Resource-Utilization AVP reports the total number of sessions currently handled by the PDN-GW. In this case, both the Resource-Value and Resource-Max-Value AVPs are mandatory, to report the current and the maximum number of sessions in the PDN-GW.

- CPU_USAGE (1 )

o Indicates that the Resource-Utilization AVP reports the current CPU

usage of the PDN-GW. In this case, only the Resource-Value AVP is mandatory.

- MEMORY_USAGE (2)

o Indicates that the Resource-Utilization AVP reports the current memory usage of the PDN-GW

- PACKETJ.OSSES (3)

o Indicates that the Resource-Utilization AVP reports the current packet losses as seen by the PDN-GW

- QOE (4)

o Indicates the estimated overall Quality of Experience as perceived by the PDN-GW. The Resource-Utilization AVP reports the estimated overall QoE, in a range from 0 (worst) to 100 (best). Resource-Value A VP

This AVP is of type Unsigned32 and indicates the current value of the type of resource indicated in the Resource-Type AVP. Its concrete meaning depends on the Resource-Type AVP defined above.

Resource-Max-Value A VP

This AVP is of type Unsigned32, is used for the resource types where it's defined, and indicates the maximum value of the type of resource indicated in the Resource-Type AVP. Its concrete meaning depends on the Resource-Type AVP defined above.

MIP6-Agent-lnfo AVP

This AVP, included in the Smp CCA Initial message, conveys information about each one of the selected PDN-GWs, and is sent from the PCRF to the MME in Figure 4. Some embodiments herein extend this AVP to include information about the weight assigned to the PDN-GW:

MIP6-Agent-lnfo ::= < AVP-Header: 486 >

[^■■■ ]

Γ Weight 1

Weight AVP

This AVP is of type Unsigned32 and indicates the weight granted to the current PDN-GW. The weights for all the PDN-GWs provided by the PCRF are used by the MME to decide which of the available PDN-GWs is finally selected to continue with the attachment.

The embodiments herein may be used in network deployments with multiple PDN-GWs, to ensure that the PDN-GWs with certain capabilities are load balanced, because the least loaded ones may be assigned a higher weight than the most loaded ones.

Furthermore, the embodiments herein may be used in Network Function

Virtualization (NFV) deployments, where new PDN-GWs can be instantiated, to automatically assign more subscribers to the initially spawned instances. In these deployments, it may be more common to have multiple nodes with smaller capacity that will be added or removed to the network dynamically based on the operational conditions.

Note that, even though the examples above mention how to implement this logic over a Diameter interface, the concepts and the information exchange

mechanism is protocol-independent, and the same logic can be implemented over other protocols, for example using a Representational State Transfer (REST)

Application Programming Interface (API) over Hypertext Transfer Protocol (HTTP). In Figure 5, a schematic flowchart of exemplifying methods in the policy node 1 10 is shown. Accordingly, the policy node 1 10 performs a method for providing a set of indications identifying a set of user traffic nodes 130-132.

As mentioned, the policy node 1 10 manages the set of user traffic nodes 130-132 according to one or more policies for at least one of subscription and charging. Each user traffic node 130-132 of the set is capable of forwarding user traffic between a network 101 and a wireless device 160. The user traffic is assigned to a user traffic node 130-132 of the set by a mobility management node 120 for managing mobility of the wireless device 160. One or more of the following actions may be performed in any suitable order.

Action 510

This action is similar to action A020.

The policy node 1 10 receives, from said each user traffic node 130-132, respective information relating to an operating condition of said each user traffic node 130-132.

utilization of a resource of said each user traffic node 130-132, and

- a parameter relating to at least one of a number of sessions handled by said each user traffic node 130-132, a Quality of Experience, a latency, a throughput, a packet loss rate, a jitter for each said user traffic node 130-132.

The resource may comprise at least one of processing power and memory capacity.

The receiving may be performed regularly or irregularly. Action 520

This action is similar to action A030.

The policy node 1 10 determines a respective weight based on said respective information for said each user traffic node 130-132, wherein a set of respective weights comprises each respective weight for said each user traffic node 130-132.

Action 530

This action is similar to action A040.

The policy node 1 10 transmits, to the mobility management node 120 for attaching the user traffic to one of the user traffic nodes 130-132 of the set, the set of indications identifying the set of user traffic nodes 130-132 and the set of respective weights. With reference to Figure 6, a schematic block diagram of embodiments of the policy node 1 10 of Figure 1 is shown.

The policy node 1 10 may comprise a processing module 601 , such as a means for performing the methods described herein. The means may be embodied in the form of one or more hardware modules and/or one or more software modules

The policy node 1 10 may further comprise a memory 602. The memory may comprise, such as contain or store, instructions, e.g. in the form of a computer program 603, which may comprise computer readable code units. According to some embodiments herein, the policy node 1 10 and/or the processing module 601 comprises a processing circuit 604 as an exemplifying hardware module, which may comprise one or more processors. Accordingly, the processing module 601 may be embodied in the form of, or 'realized by', the processing circuit 604. The instructions may be executable by the processing circuit 604, whereby the policy node 1 10 is operative to perform the methods of Figure 2 and/or Figure 5. As another example, the instructions, when executed by the policy node 1 10 and/or the processing circuit 604, may cause the policy node 1 10 to perform the method according to Figure 2 and/or Figure 5.

In view of the above, in one example, there is provided a policy node 1 10 for providing a set of indications identifying a set of user traffic nodes 130-132. As mentioned, the policy node 1 10 manages the set of user traffic nodes 130-132 according to one or more policies for at least one of subscription and charging. Each user traffic node 130-132 of the set is capable of forwarding user traffic between a network 101 and a wireless device 160. The user traffic is assigned to a user traffic node 130-132 of the set by a mobility management node 120 for managing mobility of the wireless device 160. Again, the memory 602 contains the instructions executable by said processing circuit 604 whereby the policy node 1 10 is operative for:

receiving, from said each user traffic node 130-132, respective information relating to an operating condition of said each user traffic node 130-132,

determining a respective weight based on said respective information for said each user traffic node 130-132, wherein a set of respective weights comprises each respective weight for said each user traffic node 130-132, and

transmitting, to the mobility management node 120 for attaching the user traffic to one of the user traffic nodes 130-132 of the set, the set of indications identifying the set of user traffic nodes 130-132 and the set of respective weights.

Figure 6 further illustrates a carrier 605, or program carrier, which comprises the computer program 603 as described directly above. In some embodiments, the policy node 1 10 and/or the processing module 601 may comprise one or more of a receiving module 610, a determining module 620, and a transmitting module 630 as exemplifying hardware modules. In other examples, one or more of the aforementioned exemplifying hardware modules may be implemented as one or more software modules.

Moreover, the policy node 1 10 and/or the processing module 601 comprises an Input/Output unit 606, which may be exemplified by the receiving module and/or the transmitting module when applicable. Accordingly, the policy node 1 10 is configured for providing a set of indications identifying a set of user traffic nodes 130-132.

Therefore, according to the various embodiments described above, the policy node 110 and/or the processing module 601 and/or the receiving module 610 is configured for receiving, from said each user traffic node 130-132, respective information relating to an operating condition of said each user traffic node 130-132.

The policy node 1 10 and/or the processing module 601 and/or the determining module 620 may be configured for determining a respective weight based on said respective information for said each user traffic node 130-132, wherein a set of respective weights comprises each respective weight for said each user traffic node 130- 132.

The policy node 1 10 and/or the processing module 601 and/or the transmitting module 630 may be configured for transmitting, to the mobility management node 120 for attaching the user traffic to one of the user traffic nodes 130-132 of the set, the set of indications identifying the set of user traffic nodes 130-132 and the set of respective weights.

In Figure 7, a schematic flowchart of exemplifying methods in the mobility management node 120 is shown. Accordingly, the mobility management node 120 performs a method for selecting a user traffic node 130-132 from a set of user traffic nodes 130-132.

As mentioned, each user traffic node 130-132 of the set is capable of forwarding user traffic between a network 101 and a wireless device 160. One or more of the following actions may be performed in any suitable order.

Action 710

This action is similar to action A050.

The mobility management node 120 receives, from a policy node 1 10 for managing the set of user traffic nodes 130-132 according to one or more policies for at least one of subscription and charging, a set of indications identifying the set of user traffic nodes 130-132 and a set of respective weights for each user traffic node 130-132 of the set of user traffic nodes 130-132. Action 720

This action is similar to action A060.

The mobility management node 120 selects the user traffic node 130-132 based on the set of indications identifying the set of user traffic nodes 130-132 and the set of respective weights. The selection of the user traffic node 130-132 may comprise selecting the user traffic node 130-132 randomly or quasi randomly while taking the set of respective weights into account, wherein a respective weight may be directly or inversely related to a probability of selecting the user traffic node 130-132 that corresponds to said respective weight.

Action 730

This action is similar to action A070.

The mobility management node 120 transmits, to the selected user traffic node 130-132, a session establishment request.

With reference to Figure 8, a schematic block diagram of embodiments of the mobility management node 120 of Figure 1 is shown. The mobility management node 120 may comprise a processing module 801 , such as a means for performing the methods described herein. The means may be embodied in the form of one or more hardware modules and/or one or more software modules

The mobility management node 120 may further comprise a memory 802. The memory may comprise, such as contain or store, instructions, e.g. in the form of a computer program 803, which may comprise computer readable code units.

According to some embodiments herein, the mobility management node 120 and/or the processing module 801 comprises a processing circuit 804 as an exemplifying hardware module. Accordingly, the processing module 801 may be embodied in the form of, or 'realized by', the processing circuit 804. The instructions may be executable by the processing circuit 804, whereby the mobility management node 120 is operative to perform the methods of Figure 2 and/or Figure 7. As another example, the instructions, when executed by the mobility management node 120 and/or the processing circuit 804, may cause the mobility management node 120 to perform the method according to Figure 2 and/or Figure 7.

In view of the above, in one example, there is provided a mobility management node 120 for selecting a user traffic node 130-132 from a set of user traffic nodes 130- 132. As mentioned, each user traffic node 130-132 of the set is capable of forwarding user traffic between a network 101 and a wireless device 160. Again, the memory 802 contains the instructions executable by said processing circuit 804 whereby the mobility management node 120 is operative for:

receiving, from a policy node 110 for managing the set of user traffic nodes 130- 132 according to one or more policies for at least one of subscription and charging, a set of indications identifying the set of user traffic nodes 130-132 and a set of respective weights for each user traffic node 130-132 of the set of user traffic nodes 130-132,

selecting the user traffic node 130-132 based on the set of indications identifying the set of user traffic nodes 130-132 and the set of respective weights, and

transmitting, to the selected user traffic node 130-132, a session establishment request.

Figure 8 further illustrates a carrier 805, or program carrier, which comprises the computer program 803 as described directly above. In some embodiments, the mobility management node 120 and/or the processing module 801 comprises an Input/Output unit 806, which may be exemplified by a receiving module and/or a transmitting module when applicable.

In further embodiments, the mobility management node 120 and/or the processing module 801 may comprise one or more of a receiving module 810, a selecting module 820, and a transmitting module 830 as exemplifying hardware modules. In other examples, one or more of the aforementioned exemplifying hardware modules may be implemented as one or more software modules. Accordingly, the mobility management node 120 is configured for selecting a user traffic node 130-132 from a set of user traffic nodes 130-132.

Therefore, according to the various embodiments described above, the mobility management node 120 and/or the processing module 801 and/or the receiving module 810 is configured for receiving, from a policy node 1 10 for managing the set of user traffic nodes 130-132 according to one or more policies for at least one of subscription and charging, a set of indications identifying the set of user traffic nodes 130-132 and a set of respective weights for each user traffic node 130-132 of the set of user traffic nodes 130-132,

The mobility management node 120 and/or the processing module 801 and/or the selecting module 820 may be configured for selecting the user traffic node 130-132 based on the set of indications identifying the set of user traffic nodes 130-132 and the set of respective weights.

The mobility management node 120 and/or the processing module 801 and/or the transmitting module 830 may be configured for transmitting, to the selected user traffic node 130-132, a session establishment request.

As used herein, the term "node", or "network node", may refer to one or more physical entities, such as devices, apparatuses, computers, servers or the like. This may mean that embodiments herein may be implemented in one physical entity. Alternatively, the embodiments herein may be implemented in a plurality of physical entities, such as an arrangement comprising said one or more physical entities, i.e. the embodiments may be implemented in a distributed manner, such as on cloud system, which may comprise a set of server machines.

As used herein, the term "module" may refer to one or more functional modules, each of which may be implemented as one or more hardware modules and/or one or more software modules and/or a combined software/hardware module in a node. In some examples, the module may represent a functional unit realized as software and/or hardware of the node.

As used herein, the term "computer program carrier", "program carrier", or

"carrier", may refer to one of an electronic signal, an optical signal, a radio signal, and a computer readable medium. In some examples, the computer program carrier may exclude transitory, propagating signals, such as the electronic, optical and/or radio signal. Thus, in these examples, the computer program carrier may be a non-transitory carrier, such as a non-transitory computer readable medium.

As used herein, the term "processing module" may include one or more hardware modules, one or more software modules or a combination thereof. Any such module, be it a hardware, software or a combined hardware-software module, may be a determining means, estimating means, capturing means, associating means, comparing means, identification means, selecting means, receiving means, sending means or the like as disclosed herein. As an example, the expression "means" may be a module

corresponding to the modules listed above in conjunction with the Figures.

As used herein, the term "software module" may refer to a software application, a Dynamic Link Library (DLL), a software component, a software object, an object according to Component Object Model (COM), a software component, a software function, a software engine, an executable binary software file or the like.

The terms "processing module" or "processing circuit" may herein encompass a processing unit, comprising e.g. one or more processors, an Application Specific integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA) or the like. The processing circuit or the like may comprise one or more processor kernels.

As used herein, the expression "configured to/for" may mean that a processing circuit is configured to, such as adapted to or operative to, by means of software configuration and/or hardware configuration, perform one or more of the actions described herein.

As used herein, the term "action" may refer to an action, a step, an operation, a response, a reaction, an activity or the like. It shall be noted that an action herein may be split into two or more sub-actions as applicable. Moreover, also as applicable, it shall be noted that two or more of the actions described herein may be merged into a single action.

As used herein, the term "memory" may refer to a hard disk, a magnetic storage medium, a portable computer diskette or disc, flash memory, random access memory (RAM) or the like. Furthermore, the term "memory" may refer to an internal register memory of a processor or the like.

As used herein, the term "computer readable medium" may be a Universal Serial

Bus (USB) memory, a DVD-disc, a Blu-ray disc, a software module that is received as a stream of data, a Flash memory, a hard drive, a memory card, such as a MemoryStick, a Multimedia Card (MMC), Secure Digital (SD) card, etc. One or more of the

aforementioned examples of computer readable medium may be provided as one or more computer program products.

As used herein, the term "computer readable code units" may be text of a computer program, parts of or an entire binary file representing a computer program in a compiled format or anything there between.

As used herein, the expression "transmit" and "send" are considered to be interchangeable. These expressions include transmission by broadcasting, uni-casting, group-casting and the like. In this context, a transmission by broadcasting may be received and decoded by any authorized device within range. In case of uni-casting, one specifically addressed device may receive and decode the transmission. In case of group-casting, a group of specifically addressed devices may receive and decode the transmission.

As used herein, the terms "number" and/or "value" may be any kind of digit, such as binary, real, imaginary or rational number or the like. Moreover, "number" and/or "value" may be one or more characters, such as a letter or a string of letters. "Number" and/or "value" may also be represented by a string of bits, i.e. zeros and/or ones.

As used herein, the term "set of may refer to one or more of something. E.g. a set of devices may refer to one or more devices, a set of parameters may refer to one or more parameters or the like according to the embodiments herein.

As used herein, the expression "in some embodiments" has been used to indicate that the features of the embodiment described may be combined with any other embodiment disclosed herein.

Even though embodiments of the various aspects have been described, many different alterations, modifications and the like thereof will become apparent for those skilled in the art. The described embodiments are therefore not intended to limit the scope of the present disclosure.

Claims

1. A method, performed by a policy node (1 10), for providing a set of indications

identifying a set of user traffic nodes (130-132), wherein the policy node (1 10) manages the set of user traffic nodes (130-132) according to one or more policies for at least one of subscription and charging, wherein each user traffic node (130-132) of the set is capable of forwarding user traffic between a network (101 ) and a wireless device (160), wherein the user traffic is assigned to a user traffic node (130-132) of the set by a mobility management node (120) for managing mobility of the wireless device (160), wherein the method comprises:

receiving (A020), from said each user traffic node (130-132), respective information relating to an operating condition of said each user traffic node (130- 132),

determining (A030) a respective weight based on said respective information for said each user traffic node (130-132), wherein a set of respective weights comprises each respective weight for said each user traffic node (130-132), and transmitting (A040), to the mobility management node (120) for attaching the user traffic to one of the user traffic nodes (130-132) of the set, the set of indications identifying the set of user traffic nodes (130-132) and the set of respective weights.

2. The method according to claim 1 , wherein the operating condition of said each user traffic node (130-132) refers to at least one of:

utilization of a resource of said each user traffic node (130-132), and

a parameter relating to at least one of a number of sessions handled by said each user traffic node (130-132), a Quality of Experience, a latency, a

throughput, a packet loss rate, a jitter for each said user traffic node (130-132).

3. The method according to claim 2, wherein the resource comprises at least one of processing power and memory capacity.

4. The method according to any one of claims 1 -3, wherein the receiving is performed regularly or irregularly.

5. The method according to any one of claims 1 -4, wherein the method is performed during an attach procedure for a telecommunication network (100).

6. The method according to any one of claims 1 -5, wherein the policy node (1 10) implements a Policy and Charging Rules Function, PCRF, or a Policy Control Function, PCF.

7. The method according to any one of claims 1 -6, wherein the mobility management node (120) implements a Mobility Management Entity, MME, or an access and mobility management function, AMF.

8. The method according to any one of claims 1 -7, wherein the user traffic node (130- 132) implements a packet data network gateway, PDN-GW, a user part function, UPF, or a session management function, SMF.

9. A method, performed by a mobility management node (120), for selecting a user traffic node (130-132) from a set of user traffic nodes (130-132), wherein each user traffic node (130-132) of the set is capable of forwarding user traffic between a network (101 ) and a wireless device (160), wherein the method comprises:

receiving (A050), from a policy node (1 10) for managing the set of user traffic nodes (130-132) according to one or more policies for at least one of subscription and charging, a set of indications identifying the set of user traffic nodes (130-132) and a set of respective weights for each user traffic node (130-132) of the set of user traffic nodes (130-132),

selecting (A060) the user traffic node (130-132) based on the set of indications identifying the set of user traffic nodes (130-132) and the set of respective weights, and

transmitting (A070), to the selected user traffic node (130-132), a session establishment request.

10. The method according to claim 9, wherein the selection (A060) of the user traffic node (130-132) comprises selecting the user traffic node (130-132) randomly or quasi randomly while taking the set of respective weights into account, wherein a respective weight is directly or inversely related to a probability of selecting the user traffic node (130-132) that corresponds to said respective weight.

1 1 . The method according to any one of claims 9-10, wherein the method is performed during an attach procedure for a telecommunication network (100).

12. The method according to any one of claims 9-1 1 , wherein the policy node (1 10) implements a Policy and Charging Rules Function, PCRF, or a Policy Control

Function, PCF.

13. The method according to any one of claims 9-12, wherein the mobility management node (120) implements a Mobility Management Entity, MME, or an access and mobility management function, AMF.

14. The method according to any one of claims 9-13, wherein the user traffic node (130- 132) implements a packet data network gateway, PDN-GW, a user part function, UPF, or a session management function, SMF.

15. A computer program (603), comprising computer readable code units which when executed on a policy node (1 10) causes the policy node (110) to perform the method according to any one of claims 1 -8.

16. A carrier (605) comprising the computer program according to the preceding claim, wherein the carrier (605) is one of an electronic signal, an optical signal, a radio signal and a computer readable medium.

17. A computer program (803), comprising computer readable code units which when executed on a mobility management node (120) causes the mobility management node (120) to perform the method according to any one of claims 9-14.

18. A carrier (805) comprising the computer program according to the preceding claim, wherein the carrier (805) is one of an electronic signal, an optical signal, a radio signal and a computer readable medium.

19. A policy node (1 10) configured for providing a set of indications identifying a set of user traffic nodes (130-132), wherein the policy node (1 10) manages the set of user traffic nodes (130-132) according to one or more policies for at least one of subscription and charging, wherein each user traffic node (130-132) of the set is capable of forwarding user traffic between a network (101 ) and a wireless device (160), wherein the user traffic is assigned to a user traffic node (130-132) of the set by a mobility management node (120) for managing mobility of the wireless device (160), wherein the policy node (1 10) is configured for:

receiving, from said each user traffic node (130-132), respective information relating to an operating condition of said each user traffic node (130-132),

determining a respective weight based on said respective information for said each user traffic node (130-132), wherein a set of respective weights comprises each respective weight for said each user traffic node (130-132), and

transmitting, to the mobility management node (120) for attaching the user traffic to one of the user traffic nodes (130-132) of the set, the set of indications identifying the set of user traffic nodes (130-132) and the set of respective weights.

20. The policy node (1 10) according to claim 19, wherein the operating condition of said each user traffic node (130-132) refers to at least one of:

utilization of a resource of said each user traffic node (130-132), and

21 . The policy node (1 10) according to claim 20, wherein the resource comprises at least one of processing power and memory capacity.

22. The policy node (1 10) according to any one of claims 19-21 , wherein the policy node (1 10) is configured for receiving the respective information relating to the operating condition regularly or irregularly.

23. The policy node (1 10) according to any one of claims 19-22, wherein the policy node (1 10) is configured for performing an attach procedure for a telecommunication network (100).

24. The policy node (1 10) according to any one of claims 19-23, wherein the policy node (1 10) implements a Policy and Charging Rules Function, PCRF, or a Policy Control Function, PCF.

25. The policy node (1 10) according to any one of claims 19-24, wherein the mobility management node (120) implements a Mobility Management Entity, MME, or an access and mobility management function, AMF.

26. The policy node (1 10) according to any one of claims 19-25, wherein the user traffic node (130-132) implements a packet data network gateway, PDN-GW, a user part function, UPF, or a session management function, SMF.

27. A mobility management node (120) configured for selecting a user traffic node (130- 132) from a set of user traffic nodes (130-132), wherein each user traffic node (130- 132) of the set is capable of forwarding user traffic between a network (101 ) and a wireless device (160), wherein the mobility management node (120) is configured for:

receiving, from a policy node (1 10) for managing the set of user traffic nodes (130-132) according to one or more policies for at least one of subscription and charging, a set of indications identifying the set of user traffic nodes (130-132) and a set of respective weights for each user traffic node (130-132) of the set of user traffic nodes (130-132),

selecting the user traffic node (130-132) based on the set of indications identifying the set of user traffic nodes (130-132) and the set of respective weights, and

transmitting, to the selected user traffic node (130-132), a session establishment request.

28. The mobility management node (120) according to claim 27, wherein the mobility management node (120) is configured for selecting the user traffic node (130-132) randomly or quasi randomly while taking the set of respective weights into account, wherein a respective weight is directly or inversely related to a probability of selecting the user traffic node (130-132) that corresponds to said respective weight.

29. The mobility management node (120) according to any one of claims 27-28, wherein the mobility management node (120) is configured to perform an attach procedure for a telecommunication network (100).

30. The mobility management node (120) according to any one of claims 27-29, wherein the policy node (1 10) implements a Policy and Charging Rules Function, PCRF, or a Policy Control Function, PCF.

31 . The mobility management node (120) according to any one of claims 27-30, wherein the mobility management node (120) implements a Mobility Management Entity, MME, or an access and mobility management function, AMF.

32. The mobility management node (120) according to any one of claims 27-31 , wherein the user traffic node (130-132) implements a packet data network gateway, PDN- GW, a user part function, UPF, or a session management function, SMF.