WO2015048992A1

WO2015048992A1 - Handling overload of a network node

Info

Publication number: WO2015048992A1
Application number: PCT/EP2013/070547
Authority: WO
Inventors: Yong Yang; Anders FRÈDEN; Tony Olsson
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2013-10-02
Filing date: 2013-10-02
Publication date: 2015-04-09

Abstract

The present disclosure is directed to a method in a first network node (101) and a first node for performing the method, wherein the method is handling overload of a second network node (103) in a communications network (100), the method comprising: when overload of the second network node (103) is detected, transmitting (203, 305, 403, 505, 608, 721, 803), to the third network node (105), information indicating that the second network node (103) is overloaded and information indicating the identity of the second network node (103).

Description

HANDLING OVERLOAD OF A NETWORK NODE

TECHNICAL FIELD

Embodiments herein relate generally to a first network node, a method in the first network node, a third network node and a method in the third network node. More particularly the embodiments herein relate to for handling overload of a second network node in a communications network.

BACKGROUND

The Third Generation Partnership Project (3GPP) has concluded a new technical study - Core Network (CN) overload study, which aims for:

1 . Identify and document events that have occurred and caused network

disturbances due to signalling overload. In addition, identify and document scenarios that have high probability of occurrence in the 3GPP network, which may result in signalling overload for core network entities. Such scenarios/events may include Home location register/Home Subscriber Server (HLR/HSS) overload by Radio Network Controller (RNC) restart, denial of service attacks, and misbehaving/3GPP-non-compliant wireless devices causing unpredictable system response.

2. Analyse the criticality of the scenarios and determine whether it is required to take actions for the identified scenarios.

3. Study ways to mitigate and/or eliminate the impact on the core network from

signalling overload scenarios that are identified to be critical. Overload control is applicable to almost all interfaces specified in 3GPP, e.g. Gx interface which is covered by Diameter Overload control mechanism.

So there are quite some network scenarios which may lead to signaling overload over different interfaces between network nodes, and the solutions for these signalling overload scenarios may be for example to avoid the core network signalling overload, e.g. load re-balance, or signaling optimization, or to mitigate overload situation when a network node is about to be overloaded.

SUMMARY

An objective of embodiments herein is therefore to provide improved overload control in a communications network.

According to a first aspect, the object is achieved by a method in a first network node for handling overload of a second network node in a communications network. When overload of the second network node is detected, the first network node transmits, to a third network node, information indicating that the second network node is overloaded and information indicating the identity of the second network node, so as to enable the third network node to control the overload of the second network node.

It should be noted that transmitting overload and identity information from the first node to the third node may merely enable the third node to control the overload of the second node. This does not necessarily mean that the third node will actually do that, or that the third node is even capable of doing that. Rather, the information makes it possible for a capable third node to control the overload of the second node.

According to a second aspect, the object is achieved by a method in a third network node for handling overload of a second network node in a communications network. The third network node receives information, from the first network node, information indicating that the second network node is overloaded and information indicating the identity of the second network node. The third network node obtains information indicating at least one, PDN connection associated with the identity of the second network node. The third network node determines to apply overload control towards the second network node and the associated at least one PDN connection for which information has been obtained.

According to a third aspect, the object is achieved by a first network node for handling overload of a second network node in a communications network. The first network node comprises a transmitter which is adapted to detect overload of the second network node and then transmit, to a third network node, information indicating that the second network node is overloaded and information indicating the identity of the second network node, so as to enable the third network node to control the overload of the second network node.

According to a fourth aspect, the object is achieved by a third network node for handling overload of a second network node in a communications network. The third network node comprises a receiver which is adapted to receive information, from a first network node, information indicating that the second network node is overloaded and information indicating the identity of the second network node. The third network node comprises an obtaining unit which is adapted to obtain information indicating at least one PDN connection associated with the identity of the second network node. The third network node comprises a determining unit which is adapted to determine to apply overload control towards the second network node and the associated at least one PDN connection for which information has been obtained. Since the information indicating that the second network node is overloaded and information indicating the identity of the second network node is transmitted to the third network node, improved signaling overload control in a communications network is provided. Embodiments herein afford many advantages, of which a non-exhaustive list of examples follows:

Some embodiments herein allows receiving of signaling overload information in the first network node from the second network, and further transferring the signaling overload information from the first network node to the third network node. Thus, the third network node may perform signaling reduction specifically towards the second network node.

Some embodiments herein provide an advantage of improved signaling efficiency. The GTP request messages sent from the third network node to the second network node are deemed to be rejected due to downstream node overload situation according to the previous technology. With the embodiments herein, the signaling efficiency is improved by skipping transmission of those GTP messages which would have been deemed to be rejected in the previous technology. Another advantage of some embodiments herein is that since the information transmitted in embodiments herein are piggybacked on existing signaling messages, the

embodiments herein does not provide any extra signaling. A further advantage of some embodiments herein is that they are fully backward

compatible with older technology.

The embodiments herein are not limited to the features and advantages mentioned

above. A person skilled in the art will recognize additional features and advantages upon reading the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS The embodiments herein will now be further described in more detail in the following detailed description by reference to the appended drawings illustrating the embodiments and in which:

Figure 1a is a schematic block diagram illustrating embodiments of a communications network.

Figure 1 b is a schematic block diagram illustrating embodiments of a communications network.

Figure 1c is a schematic block diagram illustrating embodiments of a communications network.

Figure 2 is a signaling diagram illustrating embodiments of a method in a communications network.

Figure 3 is a signaling diagram illustrating embodiments of a method in a communications network.

Figure 4 is a signaling diagram illustrating embodiments of a method in a communications network.

Figure 5 is a signaling diagram illustrating embodiments of a method in a communications network.

Figure 6 is a signaling diagram illustrating embodiments of a method in a communications network. Figure 7 a is a signaling diagram illustrating embodiments of a method in a communications network.

Figure 7b is a continuation of figure 7a.

Figure 8 is a flow chart illustrating embodiments of a method in a first network node.

Figure 9 is a schematic block diagram illustrating embodiments of a first network node.

Figure 10a is a flow chart illustrating embodiments of a method in a third network node.

Figure 10b is a continuation of figure 10a.

Figure 1 1 is a schematic block diagram illustrating embodiments of a third network node. The drawings are not necessarily to scale and the dimensions of certain features may have been exaggerated for the sake of clarity. Emphasis is instead placed upon

illustrating the principle of the embodiments herein.

DETAILED DESCRIPTION

Embodiments herein relate to receiving and/or detecting in a first network node an

overload of a second network node, and then transmitting to a third network node

information indicating that the second network node is overloaded and indicating the identity of the second network node. This enables the third network node to control the overload of the second network node, e.g. perform signaling reduction specifically towards that second network node. This may involve associating a PDN connection with that overloaded second network node. The overload may be signaling overload.

Figure 1 a depicts a communications network 100 in which embodiments herein may be implemented. The communications network 100 may in some embodiments apply to one or more radio access technologies such as for example Long Term Evolution (LTE), LTE Advanced, Wideband Code Division Multiple Access (WCDMA), WiMax, Wifi, Global

System for Mobile Communications (GSM), or any other radio access technology,

or other radio access technologies such as Wireless Local Area Network (WLAN).

The communications network 100 comprises a first network node 101 connected to a second network node 103 and connected to a third network node 105. It should be noted that the links between the first network node 101 , the second network node 103 and the third network node 105 may be of any suitable wired link. The link may use any

suitable protocol depending on type and level of layer (e.g. as indicated by the Open

Systems Interconnection (OSI) model) as understood by the person skilled in the art. From the perspective of a signaling message direction, the overloaded node may be referred to as a downstream node. The upstream node is the node which may apply overload control, i.e. reduce the traffic towards the downstream node.

5

Figures 1 b and 1 c illustrates two different embodiments of the communications network 100 in figure 1. Figure 1b illustrates an embodiment where the first network node 101 may be represented by a PGW or a GGSN and the second network node 103 may be represented by one of a PCRF, PCEF, OCS and Radius Server. The third network node

10 105 may, in figure 1 b, be represented by one of a MME, a SGSN, an ePDG, a TWAN and a SGW. In some embodiments, the MME and SGSN are separate network nodes. In other embodiments, the MME and SGSN are co-located in one network node. In the following text, the term MME is used when referring to a standalone MME, a standalone SGSN or to a co-located MME/SGSN. The different abbreviations above will be

15 described in more detail below.

In other words, the following combinations seen in table 1 may be valid. The right column represents the first network node 101 , the middle column represents the second network node 103 and the left column represents the third network node 105.

Table 1

Figure 1 c illustrates another embodiment where the first network node may 101 may be represented by a PGW or a GGSN, similar to figure 1 b. In figure 1 c, the second network node 103 may be represented by one of a MME, a SGSN, an ePDG, a TWAN and a SGW. The third network node 101 may be represented by one of a PCRF, PCEF, OCS and Radius Server. In other words, the following combinations seen in table 2 may be valid. The right column represents the first network node 101 , the middle column represents the third network node 105 and the left column represents the second network node 103.

Table 2

A PGW, short for Packet data network GateWay and sometimes referred to as PDN GW, is a network node of the communications network 100 which provides connectivity from a wireless device to external Packet Data Networks (PDN) by being the point of entry and/or exit of the traffic for the wireless device. A wireless device may have simultaneous

connectivity with more than one PGW for accessing multiple PDNs.

The GGSN, short for Gateway GPRS Support Node, is a network node which is responsible for the interworking between the GPRS network and an external network such as e.g. the Internet. GPRS is short for general packet radio service. The GGSN keeps a record of all active wireless devices and a Serving GPRS Support Node (SGSN) attached to the wireless device. The GGSN allocates IP addresses to the wireless devices and is responsible for billing.

MME, short for Mobility Management Entity, is a network node which performs management of handovers by selecting a new (target) MME for handovers to 2G or 3G 3GPP access networks. The MME sets up, modifies, and releases default and dedicated bearers.

A SGSN is a network node which is responsible for the delivery of data packets from and to the wireless device(s) within its geographical service area. Its tasks comprises packet routing and transfer, mobility management, logical link management, authentication and charging functions etc. In some embodiments, the MME is co-located with a SGSN in one network node. An ePDG, short for evolved Packet Data Gateway, is a network node which is responsible for securing the data transmission with a wireless device connected to the Evolved Packet Core (EPC) over an untrusted non-3GPP access.

A TWAN, short for Trusted WLAN Access Network, is a WLAN network interfaced with the Evolved Packet Core as a trusted non-3GPP access via the STa interface to the 3GPP

Authentication, Authorization, and Accounting (AAA) Server/Proxy and the S2a interface to the PDN GW.

A SGW, short for Serving GateWay, is a network node which is responsible for handovers with neighboring base station, data transfer in terms of all packets across user plane and mobility interface (or anchors) to other 3GPP systems (2G and 3G) etc. A PCRF, short for Policy and Charging Rules Function, is a function implemented in a network node which provides policy control and flow based charging control decisions in the

communications network 100.

A PCEF, short for Policy and Charging Enforcement Function, is a function implemented in a network node and provides policy enforcement along with follow based charging functionalities. It is responsible of providing controller functions in traffic handling and QOS at the network node in which it is implemented over the user plane, and providing service data flow detection, counting with including online and offline different charging interactions. OCS, short for Online Charging System, provides credit management and grants credit to the PCEF based on time, traffic volume or chargeable events.

A Radius Server, where Radius is short for Remote access dial in user service, provides AAA management for wireless devices that connect and use a network service.

Currently, there is no solution in General packet radio service Tunneling Protocol (GTP) protocols, e.g. in GTP version 2 (GTPv2), to transfer the signalling overload information received from the second network node 103 which makes some of requests from the third network node 105 be deemed rejected (due to the signaling overload situation); this implies unnecessary signaling over the GTP interface. 3GPP has specified that it should be possible to provide the signaling overload

information per network node level and per Access Point Name (APN) level. Using figure 1 b as an example. The second network node 103, e.g. the PCRF, is selected by the first network node 101 , e.g. PGW not only per APN, but also per wireless device identifier, e.g. I MSI NS, MSISDN, and other selection algorisms may also be used. See the following excerpted requirements: A PCEF may be served by one or more PCRF nodes. The PCEF shall contact the

appropriate PCRF based on the PDN connected to, together with, a wireless device identity information (if available, and which may be IP CAN specific). It shall be possible to ensure that the same PCRF is contacted for a specific wireless device irrespective of the I P CAN used. I P CAN is short for Internet Protocol Connectivity Access Network.

Here the PCRF is just one of example of a second network node 103. Other examples of a second node 103 are PCEF, Online Charging System (OCS), Radius server etc.

The issue is also valid in the other "direction", i.e. in the example embodiment of figure 1 c, e.g. when a first network node 101 , e.g. PGW, has received overload control information from the second network node 103, e.g. MME/SGSN. In such embodiment, a question is how the first network node 101 should report the overload control information to the third network node 105, e.g. PCRF. The PCRF may authorize/modify PCC rules for the PDN connections associated with that overloaded second network node 103, e.g. MME/SGSN, to generate more signaling.

The method for handling overload of a second network node 103 in a communications network 100 according to some embodiments will now be described with reference to the signaling diagram depicted in Figure 2. In figure 2, the embodiment of the communications network 100 in figure 1 a is used as an example. However, the method of figure 2 is equally applicable to the embodiments seen in figures 1 b and 1 c. Method steps which are specific for each of the embodiments in figures 1 b and 1 c will be described with reference to figures 3, 4 and 5. The method of figure 2 comprises the following steps, which steps may as well be carried out in another suitable order than described below: Step 200

In some embodiments, the third network node 105 sends, to the first network node 101 , information indicating that it supports receipt of overload information and that it has capability to control overload, i.e. that it is capable of receiving overload information.

Step 201

The second network node 103 is overloaded. Step 202

The first network node 101 detects that the second network node 103 is overloaded. In some embodiments, the detection may be that the first network node 101 receives information indicating the overload from the overloaded second network node 103 (indicated with a dotted arrow in figure 2). In addition to indicating the overload, the received information may further comprise information which indicates how much the third network node 105 needs to reduce its signaling towards the second network node 103 to control the overload. In other embodiments, the overload detection may be done internally within the first network node 101 , e.g. based on the number of unreplied messages sent to the second network node 103 and/or based on the average response time from the second network node 103. Step 203

The first network node 101 transmits information indicating that the second network node 103 is overloaded together with information indicating an identity of the second network node 103. The information indicating the identity of the second network node will be referred to as second network node ID for the sake of simplicity. In some embodiments, the transmitted information indicates how much the third network node 105 needs to reduce its signaling towards the second network node 103 to control the overload, i.e. an amount of signaling to be reduced.

Step 204

The third network node 105 receives the information in step 203 and, preferably based on this received information, obtains information indicating at least one PDN connection associated with the second network node ID. Step 205

The third network node 105 determines to apply overload control towards the second network node identified by the second network node ID and the obtained associated at least one PDN connection from step 204. This control may be to discard 3 of every 10 messages to be sent.

Step 206

The third network node 305 transmits the controlled signaling towards the second network node 103 which substantially mitigates the overload in the second network node 103. The method for handling overload of a second network node 103 in a communications network 100 according to some embodiments will now be described with reference to the signaling diagram depicted in Figure 3. In figure 3, the embodiment of the communications network 100 in figure 1 b applies. This implies that figure 3 describes the method in the embodiment where the first network node 101 is e.g. a PGW or a GGSN, where the second network node 103 is e.g. a PCRF, PCEF, OCS or a Radius server and where the third network node 105 is e.g. a MME, a SGSN, a ePDG, a TWAN or a SGW. The method comprises the following steps, which steps may as well be carried out in another suitable order than described below:

Step 300

This step corresponds to step 200 in figure 2. In some embodiments, the third network node 105 sends, to the first network node 101 , information indicating that it supports receipt of overload information and that it has capability to control overload, i.e. that it is capable of receiving overload information. Step 301

In some embodiments, at creation of a PDN connection, the second network node 103

transmits, to the third network node 105, information indicating identification of the second network node 103 and information indicating the PDN connection. The identification of the second network node 103 may be an explicit identification or an index to a location where the identification is found. The identification may also be any other implicit identification, such as for example embedding the identification in an octet of the TEI D-C range. The PDN connection information may comprise any suitable explicit or implicit identification of the PDN connection.

As mentioned previously, a PGW provides connectivity from a wireless device to a PDN by being the point of entry and/or exit of the traffic for the wireless device, and a wireless device may have simultaneous connectivity with more than one PGW for accessing multiple PDNs. Thus, a PDN connection is the association between the wireless device and the PDN. The second network node obtains information indicating the PDN connection during the PDN connection establishment procedure. The PDN connection maybe represented by for example an Internet Protocol (IP) address together with an Access Pont Name (APN).

The creation of the PDN connection may involve a PDN create session establishment procedure with for example the messages PDN create session Request and PDN create session Response.

As mentioned above, figure 3 illustrates an embodiment where the second network node is a PCRF, PCEF, OCS or a Radius server. A PCRF, PCEF, OCS or a Radius server would not be changed during the lifetime of a PDN connection. So as long as at the first network node 101 comprises the second network node address ID in the response

message (Create Session response message) during a PDN connection creation

procedure, it would be sufficient. Note that the third network node 105 may store the second network node ID and transfer it to the next second network node.

Step 302

In some embodiments, the third network node 105 stores the second network node ID together with the information indicating the PDN connection. This way, the third network node 105 comprises stored information about the association between the second network node ID and the PDN connection. The information may be stored in for example the form of a table having the node ID in one column and the associated PDN connection in the other column.

Step 303

This step corresponds to step 201 in figure 2. The second network node is overloaded. Step 304

This step corresponds to step 202 in figure 2. The first network node 101 detects that the second network node 103 is overloaded. In some embodiments, the detection may be that the first network node 101 receives information indicating the overload from the overloaded second network node 103 (indicated with a dotted arrow in figure 3). In addition to indicating the overload, the received information may further comprise information which indicates how much the third network node 105 needs to reduce its signaling towards the second network node 103 to control the overload. In other embodiments, the overload detection may be done internally within the first network node 101 .

Step 305

This step corresponds to step 203 in figure 2. The first network node 101 transmits, to the third network node 105, information indicating that the second network node 103 is overloaded together with information indicating an identity of the second network node 103. In some embodiments, the transmitted information indicates how much the third network node 105 needs to reduce its signaling towards the second network node 103 to control the overload.

Step 306

This step corresponds to step 204 in figure 2. The third network node 105 receives the information in step 305 and, preferably based on this received information, obtains information indicating at least one PDN connection associated with the second network node ID. In this embodiments, the third network node 105 uses the stored information from step 302 to find which PDN connection that is associated with the second network ID that was sent from the first network node in step 305.

The third network node will only perform signaling reduction for those PDN connection associated with the overloaded node. E.g. a PGW may be connected to several PCRFs, but maybe only one of the PCRFs is overloaded. Therefore should signaling reducing be performed towards that overloaded PCRF.

The third network node 105 may get to know which second network node 103 that is associated with a given PDN connection during e.g. a PDN connection creation

procedure.

For the embodiment of the communications network 100 illustrated in figure 1 b, the

information indicating the overload is transmitted to third network node 105. The second network node 103, e.g. a PCRF, would not be changed during the lifetime of a PDN

connection. So once the second network node ID is provided during a PDN connection creation procedure, it would not change.

For the embodiment of the communications network 100 illustrated in figure 1 c, for the transmission of the overload information to the third network node 105, e.g. a PCRF, the third network node 105 need to know which second network node 103 is associated with a given PDN connection. So during an inter-second network node change, the updated Identifier may need to be report to the third network node 105.

5 Step 307

This step corresponds to step 205 in figure 2. The third network node 105 determines to apply overload control towards the second network node identified by the second network node ID and the obtained associated at least one PDN connection from step 306.

10 Step 308

This step corresponds to step 206 in figure 2. The third network node 305 transmits the controlled signaling towards the second network node 103 which substantially mitigates the overload in the second network node 103.

15 The method for handling overload of a second network node 103 in a communications network 100 according to some embodiments will now be described with reference to the signaling diagram depicted in Figure 4. In figure 4, the embodiment of the communications network 100 in figure 1 b also applies. This implies that figure 4 describes the method in the embodiment where the first network node 101 is e.g. a PGW or a GGSN, where the second network node

20 103 is e.g. a PCRF, PCEF, OCS or a Radius server and where the third network node 105 is e.g. a MME, a SGSN, a ePDG, a TWAN or a SGW. The method comprises the following steps, which steps may as well be carried out in another suitable order than described below:

Step 400

25 This step corresponds to step 200 in figure 2 and step 300 in figure 3. In some embodiments, the third network node 105 sends, to the first network node 101 , information indicating that it supports receipt of overload information and that it has capability to control overload, i.e. that it is capable of receiving overload information.

30 Step 401

This step corresponds to step 201 in figure 2 and step 303 in figure 3. The second network node 103 is overloaded, which is in this embodiment for example a PCRF, PCEF, OCS or a Radius server. Step 402

This step corresponds to step 202 in figure 2 and to step 304 in figure 3. The first network node 101 detects that the second network node 103 is overloaded. In some embodiments, the detection may be that the first network node 101 receives information indicating the overload from the overloaded second network node 103 (indicated with a dotted arrow in figure 2). In addition to indicating the overload, the received information may further comprise information which indicates how much the third network node 105 needs to reduce its signaling towards the second network node 103 to control the overload. In other embodiments, the overload detection may be done internally within the first network node 101.

Step 403

This step corresponds to step 203 in figure 2 and to step 305 in figure 3. The first network node 101 transmits information indicating that the second network node 103 is overloaded together with information indicating an identity of the second network node 103. The information indicating the identity of the second network node will be referred to as second network node ID for the sake of simplicity. In this embodiment, the second network node ID is for example an IMSI NS, MSISDN NS or any charging characteristics. In some embodiments, the transmitted information indicates how much the third network node 105 needs to reduce its signaling towards the second network node 103 to control the overload.

Step 404

This step corresponds to step 204 in figure 2 and to step 306 in figure 3. The third network node 105 receives the information in step 403 and, preferably based on this received information, obtains information indicating at least one PDN connection associated with the second network node ID.

Step 405

This step corresponds to step 205 in figure 2 and to step 307 in figure 3. The third network node 105 determines to apply overload control towards the second network node identified by the second network node ID and the obtained associated at least one PDN connection from step 204. Step 406

This step corresponds to step 206 in figure 2 and to step 308 in figure 3. The third network node 305 transmits the controlled signaling towards the second network node 103 which substantially mitigates the overload in the second network node 103.

The method for handling overload of a second network node 103 in a communications network 100 according to some embodiments will now be described with reference to the signaling diagram depicted in Figure 5. In figure 5, the embodiment of the communications network 100 in figure 1 c applies. This implies that figure 5 describes the method in the embodiment where the first network node 101 is e.g. a PGW or a GGSN, where the second network node 103 is e.g. a MME, a SGSN, an ePDG, a TWAN or a SGW and where the third network node 105 is e.g. a PCRF, PCEF, OCS or a Radius server. The method comprises the following steps, which steps may as well be carried out in another suitable order than described below: Step 500

This step corresponds to step 200 in figure 2, step 300 in figure 3 and step 400 in figure 4. In some embodiments, the third network node 105 sends, to the first network node 101 , information indicating that it supports receipt of overload information and that it has capability to control overload, i.e. that it is capable of receiving overload information.

Step 501

In some embodiments, at an IP Connectivity Access Network (IP-CAN) procedure, the second network node 103 transmits, to the third network node 105, information indicating identification of the second network node 103 and information indicating the PDN

connection. The identification of the second network node 103 may be an explicit

identification or an index to a location where the identification is found. The identification may also be any other implicit identification, such as for example embedding the

identification in an octet of the TEID-C range. The TEID-C range may be assigned during a PDN connection creation procedure. The PDN connection information may comprise any suitable explicit or implicit identification of the PDN connection.

IP-CAN is an access network that provides IP connectivity. The IP-CAN procedure may be for example a session establishment procedure or a session modification procedure.

The IP-CAN session establishment may correspond to an IP address assignment. So, if the same wireless device is assigned multiple IP addresses (for example, if the same wireless device is assigned an IPv4 and IPv6 address), each such address assignment is considered as a new IP-CAN session establishment. An IP-CAN procedure is associated with a PDN connection. For example, a PCEF establishes the IP-CAN Session during the Gateway Control session establishment. This happens when the wireless device

attaches to the EPC for the first time and when the wireless device establishes a new

PDN Connection. In relation to IP-CAN, the PCEF is a functional entity in the Gateway node implementing the IP access to the PDN.

As mentioned above, the second network node 103 obtains the information indicating the PDN connection during the IP_CAN session establishment procedure, which as part of a PDN connection establishment procedure. An IP-CAN session establishment procedure is to setup an association between the PCEF and the PCRF for the PDN connection, to allow the PCRF to provide policy and charging control. It is the same wireless device IP address and APN which may be used to identify the IP-CAN.

Step 502

This step corresponds to step 302 in figure 2. In some embodiments, the third network node 105 stores the second network node ID together with the information indicating the PDN connection. This way, the third network node 105 comprises stored information about the association between the second network node ID and the PDN connection. The information may be stored in for example the form of a table having the node ID in one column and the associated PDN connection in the other column.

Step 503

This step corresponds to step 201 in figure 2, step 303 in figure 2 and step 401 in figure 4. The second network node 103 is overloaded.

Step 504

This step corresponds to step 202 in figure 2, step 304 in figure 3 and step 402 in figure 4. The first network node 101 detects that the second network node 103 is overloaded. In some embodiments, the detection may be that the first network node 101 receives information indicating the overload from the overloaded second network node 103 (indicated with a dotted arrow in figure 5). In addition to indicating the overload, the received information may further comprise information which indicates how much the third network node 105 needs to reduce its signaling towards the second network node 103 to control the overload. In other embodiments, the overload detection may be done internally within the first network node 101.

Step 505

This step corresponds to step 203 in figure 2, step 305 in figure 3 and step 403 in figure 4. The first network node 101 transmits information indicating that the second network node 103 is overloaded together with information indicating an identity of the second network node 103. In some embodiments, the transmitted information indicates how much the third network node 105 needs to reduce its signaling towards the second network node 103 to control the overload.

Step 506

This step corresponds to step 204 in figure 2, step 306 in figure 3 and step 404 in figure 4. The third network node 105 receives the information in step 505 and, preferably based on this received information, obtains information indicating at least one PDN connection associated with the second network node ID. In this embodiments, the third network node 105 uses the stored information from step 502 to find which PDN connection that is associated with the second network ID that was sent from the first network node in step 505.

Step 507

This step corresponds to step 205 in figure 2, step 307 in figure 3 and step 405 in figure 4. The third network node 105 determines to apply overload control towards the second network node identified by the second network node ID and the obtained associated at least one PDN connection from step 506. Step 508

This step corresponds to step 206 in figure 2, step 308 in figure 3 and step 406 in figure 4. The third network node 305 transmits the controlled signaling towards the second network node 103 which substantially mitigates the overload in the second network node 103. As seen from figures 2, 3, 4 and 5, there are three alternatives for associating the

overloaded second network node with the respective PDN connection. For example, if a PGW has received overload control information from the PCRF, e.g. reduce the signaling traffic with 30%, the PGW may transfer such information to the MME/SGSN, to request the MME/SGSN to suppress sending GTP messages which trigger Gx signaling more than what the PCRF may handle. This requires that the MME/SGSN may associate the PDN connection to that overloaded PCRF. The Gx signaling mentioned above, is signaling on a Gx interface. The Gx interface is between the PCRF and the PCEF. The Gx interface is responsible for e.g. provisioning and removal of Policy and Charging Control (PCC) rules from the PCRF to the PCEF, transmission of traffic plane events from the PCEF to the PCRF, charging control, policy control or both.

These three alternatives are as follows. Alternative 1 )

In some embodiments, during a PDN connection creation procedure, information indicating the identity of the second network node 103, e.g. a PCRF identifier, an OCS identifier or the index of them is provided by the first network node 101 via an explicit information element. The information element comprises the second network node ID or an index of the second network node ID. Alternative 2)

In some embodiments, the second network node ID is provided implicitly to the first network node 101. For example, when the first network node 101 provides a TEID-C on the control plane of its own, it may embed the index of second network node 103 in some bits of TEID. The number of bits and position of those bits in the TEID are subject for standardization or by configuration based on operators provisioning. For example, the PGW 101 is connected with PCRF1 , PCRF2, OCS1 , OCS2 and Radius server 1. The PGW 101 allocates TEID-C for a given PDN connection at creation. E.g. four bits in the TEID-C is used to identify the second network node 103 and starting from the second Octet of the TEID-C. For a PDN connection which is using PCRF1 , the TEID-C "xx 1x xx xx" may be allocated. For a PDN connection which is using PCRF2, the TEID-C "xx 2x xx xx" may be allocated. When the MME/SGSN later receives overload control information associated with the TEID-C "xx 2x xx xx" from the PGW, the MME/SGSN shall perform signaling reduction only for the PGW TEID-C with "xx 2x xx xx". This is because the MME already knows which PGW is used for a certain PDN connection, and by using an "index" that points to a certain second network node 103, e.g. a PCRF (known by that PGW), the MME will be able to throttle requests that involve that second network node 103, e.g. PCRF. This approach gives a great flexibility, requires no storage in MME/SGSN to store second network node identifiers. Alternative 3)

In another embodiment, the first network node 101 , e.g. the PGW, provides the parameters which are used for the selection of second network node 103 by the PGW directly with the overload control information. Such parameters may be e.g. IMSI Number Series, MSISDN NS, Charging Characteristics and so on. In this way, the parameters are provide together with the overload control information to indicate to the MME/SGSN that signaling reduction (which may be indicated in the Overload Control information) is only applicable to those IMSI NS, MSISDN and so on. The method for handling overload of the second network node 103 in the communications network 100 according to some embodiments will now be described with reference to the signaling diagram depicted in Figure 6. In figure 6, the first network node 101 is exemplified with a PGW, the second network node 103 is exemplified with a PCRF and the third network node 105 is exemplified with a MME, i.e. corresponding to the embodiment of the communications network 100 illustrated in figure 1 b. When describing figure 6, the reference number 101 is therefore used when referring to the PGW, the reference number 103 is used when referring to the PCR and the reference number 105 is used when referring to the MME. The PCRF 103 is the overloaded node and the MME 105 is the node which controls the overload. In addition to the PGW 101 , the PCRF 103 and the MME 105, a SGW 110 is illustrated in figure 6. The method shown in figure 6 comprises an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) initial attach (steps 601-604) and a subsequent Service Request procedure with User Location Information (ULI) included (steps 606-609). The Service Request procedure triggers S5/S8 signaling towards the PGW 101 . The PCRF 103 has been overloaded (step 605). The method comprises the following steps, which steps may as well be carried out in another suitable order than described below:

Step 601

This step is part of the E-UTRAN initial attach procedure. The MME 105 sends a Create Session Request message to the SGW 1 10. The message comprises information which indicates that the MME 105 supports receipt of overload information and that the MME 105 is capable of controlling overload of the second network node 103. This information may be in the form of a flag, e.g. referred to as a "downstream node Flag". The

"downstream node Flag" may be in the form of an Information Element (IE) In the message, the PCRF 103 which the MME 105 is capable of overload controlling may be identified with a TEID-C range, or additional parameters, e.g. I MSI NS, or any suitable given second network node identifier as described above in the three alternatives.

Step 602

This step is part of the E-UTRAN initial attach procedure. The SGW 1 10 forwards the Create Session Request message from step 301 to the PGW 101. The PGW 101 may keep the information untouched which indicates that the MME 105 supports receipt of overload information and that the MME 105 is capable of controlling overload of the PCRF 103 if the PGW 101 supports this received information, i.e. if it supports the IE.

Step 603

This step is part of the E-UTRAN initial attach procedure. The PGW 101 sends a Create Session Response message to the SGW 110. This Create Session Response message is a response to the Create Session Request message in step 602. The messages comprises the same information as the Create Session Request message, i.e. the information which indicates that the MME 105 supports receipt of overload information and that the MME is capable of controlling overload of the PCRF 103. The information is repeated in the Create Session Response message as a confirmation that the PGW 101 supports this function. In addition, the Create Session Response message may comprise an identifier of the second network node 103. The identifier of the PCRF 103 may be comprised in the response message in case alternative 1 ) of how to link the PDN connection with the overloaded PCRF 103 is used.

Step 604

This step is part of the E-UTRAN initial attach procedure. The SGW 1 10 forwards the Create Session Response message to the MME 105. It is the same message as in step 603 which is forwarded to the MME 105.

Step 605

This step corresponds to step 202 in figure 2, step 304 in figure 3, step 402 in figure 4 and step 504 in figure 5. The PGW 101 detects that the PCRF 103 has overloaded. The detection may be that the PGW 101 receives information indicating that the PCRF 103 has overloaded, , as seen with the arrow 605 in figure 6, or that the PGW 101 detects the overload using internal algorithms within the PGW 101 e.g. algorithms using such parameters at the number of un-replied messages sent to the PCRF 103 and/or the average response time from the PCRF 103. The PGW 101 may also in this embodiment determine the how much the signaling should be reduced towards the PCRF 103 to control the overload. The amount of signaling may be for example a percentage figure. The overload information received from the PCRF 103 may for example comprise a request for that there should be a 30% signaling reduction towards the PCRF 103.

Step 606

This step is part of the Service Request procedure. The MME 105 sends a Modify Bearer Request message to the SGW 1 10. The Modify Bearer Request message may comprise User Location Information (ULI). ULI may comprise information indicating the location of the user, i.e. the wireless device. Such information may be represented by e.g. Cell Global Identification (CGI), Service Area Identification (SAI), E-UTRAN Cell Global Identification (ECGI), Tracking Area Identity (TAI) or Routing Area Identity (RAI).

Step 607

The SGW 1 10 forwards the Modify Bearer Request message to the PGW 101. The forwarded message is the same message as in step 606.

Step 608

This step corresponds to step 203 in figure 2 and to step 403 in figure 4. The PGW 101 sends a Modify Bearer Response message to the SGW 1 10. The Modify Bearer

Response message is sent in response to the Modify Bearer Request message in step 607. Since the PGW 101 previously has detected that the PCRF 103 is overloaded in step 605, the PGW 101 comprises overload control information in the Modify Bearer Request message. The overload control information may be a request to reduce the signaling with 30% towards the PCRF 103. In addition to the overload control information, the Modify Bearer Response message may further comprise information which identifies the PCRF 103. Such identifying information may be an explicit PCRF ID or an index which points to the PCRF ID. In other embodiments, the identifying information may be a TEID-C range (which is for the PDN Connections associated with that PCRF 103), or an IMSI NS (which is for the PDN Connections associated with that PCRF 1013, i.e. PCRF 103 is selected using IMSI NS). Step 609

This step corresponds to step 203 in figure 2 and to step 403 in figure 4. The SGW 110 forwards the Modify Bearer Response message to the MME 105. The forwarded message is the same as the Modify Bearer Response message transmitted in step 308.

Step 610

This step corresponds to step 206 in figure 2, step 308 in figure 3, step 406 in figure 4 and step 508 in figure 5. With the overload control information and possibly the identifying information, the MME 103 is able to control the overload of the PCRF 103, e.g. by performing signaling reduction with the requested rate towards the specific PCRF 103.

The method for handling overload of a second network node 103 in a communications network 100 according to some embodiments will now be described with reference to the signaling diagram depicted in Figures 7a and 7b. In figure 7a and 7b, the first network node 101 is exemplified with a PGW 101 , the second network node 103 is exemplified with a second MME2 103 and the third network node 105 is exemplified with a PCRF 105, i.e. the embodiment of the communications network 100 seen in figure 1 c. Figures 7a and 7b illustrates the following further nodes which may also be comprised in the communications network 100 illustrated in figures 1 a-c: a SGW 1 10 and a first MME1 113. The second MME2 103 is the overloaded node and the PCRF is the overload control node. Note that the MME is just an example of the overloaded node and that the overloaded node may be any other node such as a SGSN, an MME, an ePDG, an SGW, a TWAN. Similarly, the PGW is just an example of the first network node 101 and that the first network node may also be for example a GGSN.

In detail, figure 7a and figure 7b depicts how the MME identifier is sent to the PCRF during an IP-CAN session establishment and session modification procedure (where there is and inter MME mobility procedure). An inter MME TAU is used as an example. Figure 7a comprises steps 701-706 and illustrates an embodiment of an E-UTRAN initial attach procedure, where an identifier of the second MME2 103 is provided to the third network node 105. Figure 7b comprises steps 707-724. Steps 707-713 in figure 7b illustrate an embodiment of a Tracking Area Update (TAU) or Routing Area Update (RAU) procedure without a SGW change procedure. The identifier of the second MME2 103 identifier is provided to the PCRF 105 if the PCRF 105 supports this feature, i.e. that the PCRF 105 has previously subscribed to the corresponding event. Steps 714-724 illustrates an embodiment of a PCRF initiated IP-CAN session modification procedure.

Note that figures 7a and 7b may comprise further steps which are not shown in figure 7. The method exemplified in figures 7a and 7b is a PCRF 105 initiated IP-CAN session modification procedure, where PCC rule(s) comprises a lead dedicate bearer creation over a GTP interface while the MME2 103 has overloaded. The MME2 103 comprises Overload control information in its Create Bearer Response message and the PGW 101 transfers the overload information to the PCRF 105 in the new CCR update message, so that the PCRF 105 may perform signaling reduction towards the MME2 103, if such Gx signaling leads the GTP signaling towards the MME2 103.

The method in figures 7a and 7b comprises the following steps, which steps may as well be carried out in another suitable order than described below:

Step 701

This step is seen in figure 7a. This step is part of the E-UTRAN initial attach procedure. The first MME1 1 13 sends a Create Session Request message to the SGW 1 10. Step 702

This step is seen in figure 7a. This step is part of the E-UTRAN initial attach procedure. The SGW 1 10 forwards the Create Session Request message to the PGW 101. The Create Session Request message is the same message as the one in step 701. Step 703

This step is seen in figure 7a. This step corresponds to step 301 in figure 3 and step 501 in figure 5. This step is part of the E-UTRAN initial attach procedure. The SGW 1 10 sends a Credit Control Request (CCR) Initial message to the PCRF 105. The CCR message comprises a MME identifier. CCR is one of two Diameter messages which are used to support Credit Control via the Diameter protocol. The purpose of the diameter credit control is to provide a framework for real-time charging. CCR is used to request credit authorization for a given service. With this step 703, the PCRF 105 stores IP-CAN session information together with the identifier of the MME1 1 13. Step 704

This step is seen in figure 7a. This step is part of the E-UTRAN initial attach procedure. The PCR 105 sends a Credit-Control-Answer (CCA) initial message to the PGW 101. The CCA initial message is a response to the CCR message in step 703. The CCA

5 message may comprise an Event Trigger - MME change. The CCA message is the second of the two Diameter messages which are used to support Credit Control via the Diameter Protocol. CCA is used to acknowledge the CCR message.

The Event-Trigger mentioned above will now be described. If the PCRF 105 is configured 10 to perform overload control towards the MME (when the MME is overloaded), it needs to ask the PGW 101 to report if the MME has changed (due to mobility procedure of the wireless device). Therefore, the PCRF 105 needs to keep track of which MME is associated with the specific PDN connection/I P-CAN session. So later on, when the PCRF 105 receives the information indicating that the MME2 103 is overloaded and

15 sends signaling to the PGW 101 , which will lead bearer signaling towards the MME2 103, the PCRF 105 may apply overload control. The overload control implies that the PCRF 105 does not send any more signaling to the MME2 103 than it can handle. The purpose of the Event Trigger is to inform the PGW 101 that the PCRF 105 supports this feature and that it needs to keep track of the MME.

20

Step 705

This step is seen in figure 7a. This step is part of the E-UTRAN initial attach procedure. The PGW 101 sends a Create Session Response message to the SGW 1 10. This Create Session Response message is a response to the message in step 702.

25

Step 706

This step is seen in figure 7a. This step is part of the E-UTRAN initial attach procedure. The SGW 1 10 forwards the Create Session Response message to the first MME1 1 113. This Create Session Response message is the same message as the one sent in step 30 705.

Step 707

This step is seen in figure 7b. This step is part of the subsequent inter MME TAU/RAU procedure. A context transfer takes place between the first MME1 1 13 and the second 35 MME2 103. Stop 708

This step is seen in figure 7b. This step is part of the subsequent inter MME TAU/RAU procedure. The second MME2 103 sends a Modify Bearer Request message to the SGW 5 1 10.

Step 709

This step is seen in figure 7b. This step is part of the subsequent inter MME TAU/RAU procedure. The SGW 1 10 forwards the Modify Bearer Request message to the PGW 10 101 . The forwarded Modify Bearer Request message is the same message as the one in step 708.

Step 710

This step is seen in figure 7b. This step corresponds to step 301 in figure 3 and to step 15 501 in figure 5. This step is part of the subsequent inter MME TAU/RAU procedure. The PGW 101 sends a CCR update message to the PCRF 105. The CCR update message may comprise an updated MME Identifier, i.e. the MME2 103 identifier.

This way, the PCRF 105, which is the node that will control overload later, comprises the identity of MME2 103.

20

Step 71 1

This step is seen in figure 7b. This step is part of the subsequent inter MME TAU/RAU procedure. The PCRF 105 sends a CCA update message to the PGW 101. The CCA update message may comprise an Event Trigger - MME change.

25

Step 712

This step is seen in figure 7b. This step is part of the subsequent inter MME TAU/RAU procedure. The PGW 101 sends a Modify Bearer Response to the SGW 1 10.

30 Step 713

This step is seen in figure 7b. This step is part of the subsequent inter MME TAU/RAU procedure. The SGW 110 forwards the Modify Bearer Response message to the second MME2 103. The forwarded Modify Bearer Response message is the same message as in step 712.

35 Step 714

This step is seen in figure 7b. This step is part of the PCRF initiated IP-CAN session modification procedure. The PCRF 105 sends a Re-Authorization Request message to the PGW 101 .

Step 715

This step is seen in figure 7b. The PGW 101 sends a Re-Authorization Acknowledgement message to the PCRF 105. The Re-Authorization Acknowledgement message is a response to the Re-Authorization Request message in step 714.

Step 716

This step is seen in figure 7b. The PGW 101 sends a Create Bearer Request message to the SGW 1 10. Step 717

This step is seen in figure 7b. The SGW 1 10 forwards the Create Bearer Request message to the second MME2 103. The forwarded Create Bearer Request message is the same message as in step 716. Step 718

This step is seen in figure 7b. The MME2 103 is overloaded. In some embodiments, the MME2 determines that the signaling needs to be reduced with a certain amount, e.g. 30%. Step 719

This step is seen in figure 7b. The second MME2 103 sends a Create Bearer Response to the SGW 1 10. This Create Bearer Response is a response to the request message sent in step 717. The MME2 103 has overloaded in step 718 and provides information indicating the overload in the Create Bearer Response. The information may be for example a request for signaling reduction of 30%. In addition to the information indicating the overload, the Create Barer Response comprises the MME2 identifier. Step 720

This step is seen in figure 7b. The SGW 1 10 forwards the Create Bearer Response message from step 719 to the PGW 101. The forwarded Create Bearer Response comprises the overload information and the MME2 identifier.

Step 721

This step is seen in figure 7b. This step corresponds to step 203 in figure 2, step 305 in figure 3, step 403 in figure 4, step 505 in figure 5 and steps 608 and 609 in figure 6. The PGW 101 sends a CCR update message to the PCRF 105. The CCR update message comprises the overload information from MME2 103 together with the MME2 identifier.

Step 722

This step is seen in figure 7b. The PCRF 105 sends a CCA update message to the PGW 101. The CCA update message is a response to the CCR update message in step 721. The CCA update message may comprise an Event Trigger - MME change. The Event Trigger is the same as described above.

Step 723

The PCRF 105 stores the information indicating that MME2 has overloaded together with the MME2 identifier and determines to apply overload control towards the MME2.

Step 724

The PCRF 105 sends controlled signaling towards the MME2 103. For example, when the PCRF 105 sends Gx signaling to the PGW 101 which trigger further bearer signaling towards the MME2 103, the PCRF 105 applies signaling overload control as requested by the MME2 103 in the step 719.

The method described above will now be described seen from the perspective of the first network node 101. Figure 8 is a flowchart describing the present method in the first network node 101 , for handling overload of a second network node 103 in a

communications network 100. In some embodiments, when the first network node 101 is represented by a PGW or a GGSN, then the second network node 103 is represented by a PCRF, a PCEF, an OCS or a Radius Server and the third network node 101 is represented by a MME, a SGSN, an ePDG, a TWAN or a SGW. In some embodiments, when the first network node 101 is represented by a PGW or a GGSN, then the second network node 103 is represented by a MME, a SGSN, an ePDG, a TWAN or a SGW and the third network node 101 is represented by one of a PCRF, PCEF, OCS or Radius Server. The method comprises the following steps to be performed by the first network node 101 , which steps may be performed in any suitable order than described below:

Step 800

This step corresponds to step 200 in figure 2, step 300 in figure 3, step 400 in figure 4 and step 500 in figure 5. In some embodiments, the first network node 101 receives, from the third network node 105, information indicating that the third network node 105 supports receipt of overload information and that the third network node 105 is capable of controlling the overload of the second network node 103.

Step 801

This step corresponds to step 301 in figure 2, step 703 in figure 7 and to step 710 in figure 7. In some embodiments, during a PDN connection creation procedure, the first network node 101 transmits, to the third network node 105, information indicating the identity of the second network node 103 and information indicating the created PDN connection associated with the second network node 103. The information indicating the identity of the second network node 103 may be one of an explicit identity of the second network node 103, an index indicating the identity of the second network node 103, a TEID-C range, an IMSI NS, a MSISDN and a charging characteristic. Step 802

This step corresponds to step 501 in figure 5. In some embodiments, during an IP-CAN procedure for a PDN, connection, the first network node 101 transmits, to the third network node 105, information indicating the identity of the second network node 103 and information indicating the PDN connection associated with the second network node 103. The IP-CAN procedure may be an IP-CAN session establishment procedure or an IP- CAN session modification procedure. The information indicating the PDN connection may be at least one of an APN and an IP address. Step 803

This step corresponds to step 305 in figure 3, step 403 in figure 4, step 505 in figure 5, step 608 in figure 6 and step 721 in figure 7. When overload of the second network node 103 is detected, the first network node 101 transmits, to the third network node 105, information indicating that the second network node 103 is overloaded and information indicating the identity of the second network node 103. The information indicating the PDN connection may be at least one of an APN and an IP address.

In some embodiments, the first network node 101 itself detects that the second network node 103 is overloaded. In some embodiments, the first network node 101 detects that the second network node 103 is overloaded by receiving information indicating the overload from the second network node 103.

In some embodiments, the information indicating that the second network node 103 is overloaded comprises information indicating how much, i.e. the amount, the third network node 103 should reduce its signaling traffic towards the second network node to control the overload of the second network node 103.

To perform the method steps shown in figure 8 for for handling overload of a second network node 103 in a communications network 100, the first network node 101 comprises an arrangement as shown in Figure 9. In some embodiments, when the first network node 101 is represented by a PGW or a GGSN, then the second network node 103 is represented by a PCRF, a PCEF, an OCS or a Radius Server and the third network node 101 is represented by a MME, a SGSN, an ePDG, a TWAN or a SGW. In some embodiments, when the first network node 101 is represented by a PGW or a GGSN, then the second network node 103 is represented by a MME, a SGSN, an ePDG, a TWAN or a SGW and the third network node 101 is represented by one of a PCRF, PCEF, OCS or Radius Server. The first network node 101 comprises a transmitter 901 which is adapted to detect overload of the second network node 103 and then transmit, to the third network node 105, information indicating that the second network node 103 is overloaded and information indicating the identity of the second network node 103. 22. In some embodiments, the transmitter 901 is further adapted to, during a PDN connection creation procedure, transmit, to the third network node 105, information indicating the identity of the second network node 103 and information indicating the created PDN connection associated with the second network node 103. In some embodiments, the transmitter 901 is further adapted to, during an IP-CAN procedure for a PDN connection, transmit, to the third network node 105, information indicating the identity of the second network node 103 and information indicating the PDN connection associated with the second network node 103. The information indicating the PDN connection may be at least one of an APN and an IP address.

The information indicating the identity of the second network node 103 may be one of an explicit identity of the second network node 103, an index indicating the identity of the second network node 103, a TEID-C range, an IMSI NS, a MSISDN and a charging characteristic.

In some embodiments, the first network node 101 comprises a receiver 903 which is adapted to receive, from the third network node 105, information indicating that the third network node 105 supports receipt of overload information and that the third network node 105 is capable of controlling the overload of the second network node 103.

In some embodiments, the information indicating that the second network node 103 is overloaded comprises information indicating how much the third network node 103 should reduce its signaling traffic towards the second network node to control the overload of the second network node 103.

The first network node 1001 may further comprise a memory 905 comprising one or more memory units. The memory 905 is arranged to be used to store data, received data streams, power level measurements, overload information, information indicating the identity of the second network node 103, information indicating the PDN connection, information indicating overload, threshold values, time periods, configurations, scheduling, and applications to perform the methods herein when being executed in the first network node 101. Those skilled in the art will also appreciate that the transmitter 901 and receiver 903 described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory, that when executed by the one or more processors such as the processor 910 perform as described below. One or more of these processors, as well as the other digital hardware, may be comprised in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).

The method described above will now be described seen from the perspective of the third network node 105. Figure 10a and figure 10b is a flowchart describing the present method in the third network node 105, for handling overload of a second network node 103 in a communications network 100. Figure 10a shows steps 1000-1005 and figure 10b shows steps 1006-1010. In some embodiments, when the first network node 101 is represented by a PGW or a GGSN, then the second network node 103 is represented by a PCRF, a PCEF, an OCS or a Radius Server and the third network node 101 is represented by a MME, a SGSN, an ePDG, a TWAN or a SGW. In some embodiments, when the first network node 101 is represented by a PGW or a GGSN, then the second network node 103 is represented by a MME, a SGSN, an ePDG, a TWAN or a SGW and the third network node 101 is represented by one of a PCRF, PCEF, OCS or Radius Server. The method comprises the following steps, which steps may be performed in any suitable order than described below: Step 1000

This step is seen in figure 10a. This step corresponds to step 200 in figure 2, step 300 in figure 3, step 400 in figure 4 and step 500 in figure 5. In some embodiments, the third network node 105 transmits, to the first network node 101 , information indicating that the third network node 105 supports receipt of overload information and that the third network node 105 is capable of controlling the overload of the second network node 103.

Step 1001

This step corresponds to step 301 in figure 3, steps 703 and 710 in figure 7. This step is seen in figure 10a. In some embodiments, during a PDN connection creation procedure, the third network node 105 receives, from the first network node 101 , information indicating the identity of the second network node 103.

The information indicating the identity of the second network node 103 may be one of an 5 explicit identity of the second network node 103, an index indicating the identity of the second network node 103, a TEID-C range, an IMSI NS, a MSISDN and a charging characteristic.

Step 1002

10 This step is seen in figure 10a. This step corresponds to step 301 in figure 3 and to steps 703 and 71 1 in figure 7. In some embodiments, during a PDN connection creation procedure, the third network node 105 obtains information indicating the created PDN connection associated with the second network node 103.

15 Step 1003

This step is seen in figure 10a. This step corresponds to step 302 in figure 2. In some embodiments, during a PDN connection creation procedure, the third network node 105 stores the received information indicating the identity of the second network node 103 and information indicating the created PDN connection associated with the second network 20 node 103.

Step 1004

This step is seen in figure 10a. This step corresponds to step 501 in figure 5. In some embodiments, during an IP-CAN procedure for a PDN connection, the third network node 25 105 receives, from the first network node 101 , information indicating the identity of the second network node 103.

Step 1005

This step is seen in figure 10a. This step corresponds to step 501 in figure 5. In some 30 embodiments, during an IP-CAN procedure for a PDN connection, the third network node 105 obtains information indicating the PDN connection associated with the second network node 103. Step 1006

This step is seen in figure 10b. This step corresponds to step 502 in figure 5. In some embodiments, during an IP-CAN procedure for a PDN connection, the third network node 105 stores the received information indicating the identity of the second network node 103 and information indicating the PDN connection.

Step 1007

This step is seen in figure 10b. This step corresponds to step 203 in figure 2, step 305 in figure 3, step 403 in figure 4, step 505 in figure 5, step 608 in figure 6 and to step 721 in figure 7. The third network node 105 receives information, from a first network node 105, information indicating that the second network node 103 is overloaded and information indicating the identity of the second network node 103.

In some embodiments, the information indicating that the second network node 103 is overloaded comprises information indicating how much the third network node 103 should reduce its signaling traffic towards the second network node 103 to control the overload of the second network node 103.

Step 1008

This step is seen in figure 10b. This step corresponds to step 204 in figure 2, step 306 in figure 3, step 404 in figure 4 and to step 506 in figure 5. The third network node 105 obtains information indicating at least one PDN connection associated with the identity of the second network node 103. The information indicating the PDN connection may be at least one of an APN and an IP address.

Step 1008a

This step is seen in figure 10b. This step corresponds to step 306 in figure 3 and to step 506 in figure 5. This is a substep of step 1008. In some embodiments, the third network node 105 obtains information indicating the at least one PDN connection associated with the identity of the second network node 103 from the stored information, i.e. the information stored in step 1003 or in step 1006.

Step 1009

This step is seen in figure 10b. This step corresponds to step 205 in figure 2, step 307 in figure 3, step 405 in figure 4 and to step 507 in figure 5. The third network node 105 determines to apply overload control towards the second network node and the associated at least one PDN connection for which information has been obtained.

Step 1010

This step is seen in figure 10b. This step corresponds to step 206 in figure 2, step 308 in figure 3, step 406 in figure 4, step 508 in figure 5 and to step 610 in figure 6. In some embodiments, the third network node 105 transmits controlled signaling traffic to the second network node 103 as determined in step 1009. To perform the method steps shown in figure 9 for for handling overload of a second network node 103 in a communications network 100, the third network node 105 comprises an arrangement as shown in Figure 11. In some embodiments, when the first network node 101 is represented by a PGW or a GGSN, then the second network node 103 is represented by a PCRF, a PCEF, an OCS or a Radius Server and the third network node 101 is represented by a MME, a SGSN, an ePDG, a TWAN or a SGW. In some embodiments, when the first network node 101 is represented by a PGW or a GGSN, then the second network node 103 is represented by a MME, a SGSN, an ePDG, a TWAN or a SGW and the third network node 101 is represented by one of a PCRF, PCEF, OCS or Radius Server.

The third network node 105 comprises a receiver 1101 which is adapted to receive information, from a first network node 101 , information indicating that the second network node 103 is overloaded and information indicating the identity of the second network node 103. The information indicating that the second network node 103 is overloaded may comprise information indicating how much the third network node 103 should reduce its signaling traffic towards the second network node 103 to control the overload of the second network node 103. The receiver 1 101 may be further adapted to, during a PDN connection creation procedure, receive, from the first network node 101 , information indicating the identity of the second network node 103. The receiver 1101 may be further adapted to, during an IP-CAN procedure for a PDN connection, receive, from the first network node 101 , information indicating the identity of the second network node 103.

The third network node 105 comprises an obtaining unit 1103 adapted to obtain information indicating at least one PDN connection associated with the identity of the second network node 103. The obtaining unit 1 103 may be further adapted to obtain information indicating the created PDN connection associated with the second network node 103. The obtaining unit 1 103 may be further adapted to obtain information indicating the PDN connection associated with the second network node 103. The obtaining unit 1 103 may be further adapted to obtain information indicating the at least one PDN 5 connection associated with the identity of the second network node 103 from the stored information.

The third network node 105 comprises a determining unit 1105 which is adapted to determine to apply overload control towards the second network node and the associated 10 at least one PDN connection for which information has been obtained.

In some embodiments, the third network node 105 comprises a transmitter 1108 which is adapted to transmit, to the first network node 101 , information indicating that the third network node 105 supports receipt of overload information and that the third network node 15 105 is capable of controlling the overload of the second network node 103. The

transmitter 1 108 may be further adapted to transmit controlled signaling traffic to the second network node 103 as determined.

The third network node 105 may further comprise a memory 1110 which is adapted to 20 store the received information indicating the identity of the second network node 103 and information indicating the created PDN connection associated with the second network node 103. The memory 1 110 may be further adapted to store the received information indicating the identity of the second network node 103 and information indicating the PDN connection. The memory 11 10 may comprise one or more memory units. The memory 25 1 110 is arranged to be used to store data, received data streams, power level

measurements, overload information, information indicating the identity of the second network node 103, information indicating the PDN connection, information indicating overload, threshold values, time periods, configurations, scheduling, and applications to perform the methods herein when being executed in the third network node 105.

30

In some embodiments, the information indicating the PDN connection is at least one of an APN and an IP address.

The information indicating the identity of the second network node 103 may be one of an 35 explicit identity of the second network node 103, an index indicating the identity of the second network node 103, a TEID-C range, an IMSI NS, a MSISDN and a charging characteristic.

Those skilled in the art will also appreciate that the transmitter 1 1 108, the receiver 1 101 , the obtaining unit 1 103 and the determining unit 1105 described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory, that when executed by the one or more processors such as the processor 1 120 perform as described below. One or more of these processors, as well as the other digital hardware, may be comprised in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).

The present mechanism for handling overload of a second network node 103 in a communications network 100 may be implemented through one or more processors, such as a processor 901 in the first network node arrangement depicted in Figure 9 and a processor 1 120 in the third network node arrangement depicted in Figure 1 , together with computer program code for performing the functions of the embodiments herein. The processor may be for example a Digital Signal Processor (DSP), Application Specific Integrated Circuit (ASIC) processor, Field-programmable gate array (FPGA) processor or microprocessor. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into the first network node 101 and/or the third network node 105. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server and downloaded to the first network node 101 and/or the third network node 105.

During Initial attach procedure, the identifier of the second network node may be provided to the third network node. In the acknowledge message from the third network node, the third network node may subscribe to a new Event Trigger (new for EPS) indicating a change of second network node, e.g. a MME/SGSN change.

During an inter second network node mobility procedure, the updated second network node identifier may be provided to the third network node. When the second network node is overloaded, the first network node reports and transfers overload control information to the third network node. If the embodiments herein are subject for standardization, then support for the embodiments herein may need to involve a handshake between the second network node 103 and the first network node 101 either via a new flag (comprised in the request and response message) along the PDN connection creation procedure, or a supported feature notification procedure.

In addition, the first network node 101 may transfer the overload information received from the second network node 103 to the third network node 105, so that the third network node 105 may perform signaling reduction towards a specific second network node 103. This requires that the first network node 101 should provide the second network node identifier to the third network node 105 during e.g. an IP-CAN session establishment.

Some embodiments described above may be summarized in the following manner: One embodiment is directed to a method in a first network node for handling overload of a second network node in a communications network. The method compromises that when overload of the second network node is detected, transmitting, to a third network node, information indicating that the second network node is overloaded and information indicating the identity of the second network node, so as to enable the third network node to control the overload of the second network node.

The method may further comprise receiving, from the third network node, information indicating that the third network node supports receipt of overload information and that the third network node is capable of controlling the overload of the second network node.

The method may further comprise transmitting, during a Packet Data Network, PDN, connection creation procedure, to the third network node, information indicating the identity of the second network node and information indicating the created PDN connection associated with the second network node. The method may further comprise transmitting, during an Internet Protocol-Connectivity Access Network, IP-CAN, procedure for a Packet Data Network, PDN, connection, to the third network node, information indicating the identity of the second network node and information indicating the PDN connection associated with the second network node.

In the method, the information indicating the PDN connection may be at least one of an Access Point Name, APN, and an Internet Protocol, IP, address.

In the method, the information indicating the identity of the second network node may be one of: an explicit identity of the second network node, an index indicating the identity of the second network node, a Tunnel Endpoint IDentifier-Control plane, TEID-C, range, a International Mobile Subscriber Identity Number Series, IMSI NS, a Mobile Subscriber Integrated Services Digital Network number series, MSISDN, and a charging

characteristic.

In the method, the first network node may itself detect that the second network node is overloaded; or the first network node may detect that the second network node is overloaded by receiving information indicating the overload from the second network node.

In the method, the information indicating that the second network node is overloaded may comprise information indicating how much the third network node should reduce its signaling traffic towards the second network node to control the overload of the second network node.

In the method the first network node may be represented by a PGW or a GGSN, the second network node may be represented by a Policy and Charging Rules Function, PCRF, a Policy and Charging Enforcement Function, PCEF, an Online Charging System, OCS, or a Radius Server and the third network node may be represented by a Mobility Management Entity, MME,, a Serving General packet radio service Support Node, SGSN, an evolved Packet Data Gateway, ePDG, a Trusted Wireless local area network Access Network, TWAN; or a Serving GateWay, SGW; or the first network node may be represented by a PGW or a GGSN, the second network node may be represented by a MME, a SGSN, an ePDG, a TWAN or a SGW and the third network node may be represented by one of a PCRF, PCEF, OCS or Radius Server. Some other embodiments described above may be summarized in the following manner:

One embodiment is directed to a method in a third network node for handling overload of a second network node in a communications network. The method comprises receiving information from a first network node, indicating that the second network node is overloaded and information indicating the identity of the second network node;

and obtaining information indicating at least one Packet Data Network, PDN, connection associated with the identity of the second network node; and determining to apply overload control towards the second network node and the associated at least one PDN connection for which information has been obtained.

The method may further comprise transmitting, to the first network node, information indicating that the third network node supports receipt of overload information and that the third network node is capable of controlling the overload of the second network node.

The method may further comprise receiving, during a Packet Data Network, PDN, connection creation procedure, from the first network node, information indicating the identity of the second network node; and obtaining information indicating the created PDN connection associated with the second network node (103); and storing the received information indicating the identity of the second network node and information indicating the created PDN connection associated with the second network node.

The method may further comprise receiving - during an Internet Protocol-Connectivity Access Network, IP-CAN, procedure for a Packet Data Network, PDN, connection - from the first network node, information indicating the identity of the second network node; and obtaining information indicating the PDN connection associated with the second network node; and storing the received information indicating the identity of the second network node and information indicating the PDN connection.

In the method, the obtaining information indicating at least one Packet Data Network, PDN, connection associated with the identity of the second network node may further comprise: obtaining information indicating the at least one PDN connection associated with the identity of the second network node from the stored information. In the method, the information indicating the PDN connection may be at least one of: an Access Point Name, APN, and an Internet Protocol, I P, address.

The method may further comprise: transmitting controlled signaling traffic to the second network node as determined.

In the method, the information indicating the identity of the second network node (103) may be one of: an explicit identity of the second network node, an index indicating the identity of the second network node, a Tunnel Endpoint IDentifier-Control plane, TEI D-C, range, a International Mobile Subscriber Identity Number Series, IMSI NS, a Mobile Subscriber Integrated Services Digital Network number, MSISDN and a charging characteristic.

In the method, the first network node may be represented by a PGW or a GGSN, the second network node (103) may be represented by a Policy and Charging Rules

Function, PCRF, a Policy and Charging Enforcement Function, PCEF, and Online Charging System, OCS, or a Radius Server and the third network node may be represented by a Mobility Management Entity, MME, a Serving General packet radio service Support Node, SGSN, an evolved Packet Data Gateway, ePDG, a Trusted Wireless local area network Access Network, TWAN, or a Serving GateWay, SGW; or the first network node may be represented by a PGW or a GGSN, the second network node may be represented by a MME, a SGSN, an ePDG, a TWAN or a SGW and the third network node may be represented by one of a PCRF, PCEF, OCS or Radius Server. Some other embodiments described above may be summarized in the following manner:

One embodiment is directed to a first network node for handling overload of a second network node in a communications network. The first network node comprises: a transmitter adapted to detect overload of the second network node and then transmit, to a third network node, information indicating that the second network node is overloaded and information indicating the identity of the second network node, so as to enable the third network node to control the overload of the second network node.

The first network node may further comprise: a receiver adapted to receive, from the third network node, information indicating that the third network node supports receipt of overload information and that the third network node is capable of controlling the overload of the second network node.

In the first network node the transmitter may be further adapted to: during a Packet Data Network, PDN, connection creation procedure, transmit to the third network node, information indicating the identity of the second network node and information indicating the created PDN connection associated with the second network node.

In first network node the transmitter may be further adapted to: during an Internet Protocol-Connectivity Access Network, IP-CAN, procedure for a Packet Data Network, PDN, connection, transmit, to the third network node, information indicating the identity of the second network node and information indicating the PDN connection associated with the second network node. For the first network node, the information indicating the PDN connection may be at least one of an Access Point Name, APN, and an Internet Protocol, IP, address.

For the first network node, the information indicating the identity of the second network node may be one of an explicit identity of the second network node, an index indicating the identity of the second network node, a Tunnel Endpoint IDentifier-Control plane, TEID- C, range, a International Mobile Subscriber Identity Number Series, IMSI NS, a Mobile Subscriber Integrated Services Digital Network number series, MSISDN, and a charging characteristic. The first network node may itself detect that the second network node is overloaded; or the first network node may detect that the second network node is overloaded by receiving information indicating the overload from the second network node.

For the first network node, the information indicating that the second network node is overloaded may comprise information indicating how much the third network node should reduce its signaling traffic towards the second network node to control the overload of the second network node.

The first network node may be represented by a PGW or a GGSN, the second network node may be represented by a Policy and Charging Rules Function, PCRF, a Policy and Charging Enforcement Function, PCEF, an Online Charging System, OCS, or a Radius Server and the third network node may be represented by a Mobility Management Entity, MME,, a Serving General packet radio service Support Node, SGSN, an evolved Packet Data Gateway, ePDG, a Terrestrial Wide Area Network, TWAN; or a Serving GateWay, SGW; or

wherein the first network node may be represented by a PGW or a GGSN, the second network node may be represented by a MME, a SGSN, an ePDG, a TWAN or a SGW and the third network node may be represented by one of a PCRF, PCEF, OCS or Radius Server.

Some other embodiments described above may be summarized in the following manner:

One embodiment is directed to a third network node for handling overload of a second network node in a communications network. The third network node comprises: a receiver adapted to receive information, from a first network node, information indicating that the second network node is overloaded and information indicating the identity of the second network node; and an obtaining unit adapted to obtain information indicating at least one Packet Data Network, PDN, connection associated with the identity of the second network node); and a determining unit adapted to determine to apply overload control towards the second network node and the associated at least one PDN connection for which

information has been obtained.

The third network node may further comprise: a transmitter adapted to transmit, to the first network node, information indicating that the third network node supports receipt of overload information and that the third network node is capable of controlling the overload of the second network node.

In the third network node the receiver may be further adapted to: during a Packet Data

Network, PDN, connection creation procedure, receive, from the first network node, information indicating the identity of the second network node; and the obtaining unit may be further adapted to: obtain information indicating the created PDN connection

associated with the second network node; and the third network node may further comprise: a memory adapted to store the received information indicating the identity of the second network node and information indicating the created PDN connection associated with the second network node. In the third network node the receiver may be further adapted to: during an Internet Protocol-Connectivity Access Network, IP-CAN, procedure for a Packet Data Network, PDN, connection, receive, from the first network node, information indicating the identity of the second network node (103); and the obtaining unit may be further adapted to: obtain information indicating the PDN connection associated with the second network node; and the third network node may further comprise: a memory adapted to store the received information indicating the identity of the second network node and information indicating the PDN connection.

In the third network node the obtaining unit may be further adapted to: obtain information indicating the at least one PDN connection associated with the identity of the second network node from the stored information.

For the third network node the information indicating the PDN connection may be at least one of an Access Point Name, APN, and an Internet Protocol, IP, address.

The third network node may further comprise: a transmitter adapted to transmit controlled signaling traffic to the second network node as determined.

For the third network node the information indicating the identity of the second network node may be one of: an explicit identity of the second network node, an index indicating the identity of the second network node, a Tunnel Endpoint IDentifier-Control plane, TEID- C, range, a International Mobile Subscriber Identity Number Series, IMSI NS, a Mobile Subscriber Integrated Services Digital Network number, MSISDN and a charging characteristic.

For the third network node the information indicating that the second network node is overloaded may comprise information indicating how much the third network node should reduce its signaling traffic towards the second network node to control the overload of the second network node. For the third network node the first network node may be represented by a PGW or a GGSN, the second network node may be represented by a Policy and Charging Rules Function, PCRF, a Policy and Charging Enforcement Function, PCEF, and Online Charging System, OCS, or a Radius Server and the third network node may be represented by a Mobility Management Entity, MME, a Serving General packet radio service Support Node, SGSN, an evolved Packet Data Gateway, ePDG, a Terrestrial Wide Area Network, TWAN, or a Serving GateWay, SGW; or the first network node may be represented by a PGW or a GGSN, the second network node may be represented by a MME, a SGSN, an ePDG, a TWAN or a SGW and the third network node may be represented by one of a PCRF, PCEF, OCS or Radius Server.

The embodiments herein are not limited to the above described embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above

embodiments should not be taken as limiting the scope of the embodiments, which is defined by the appending claims.

It should be emphasized that the term "comprises/comprising" when used in this

specification is taken to specify the presence of stated features, integers, steps or

components, but does not preclude the presence or addition of one or more other

features, integers, steps, components or groups thereof. It should also be noted that the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements.

It should also be emphasized that the steps of the methods defined in the appended claims may, without departing from the embodiments herein, be performed in another order than the order in which they appear in the claims.

Claims

1. A method in a first network node (101 ) for handling overload of a second network node (103) in a communications network (100), the method comprising:

when overload of the second network node (103) is detected, transmitting (203,

305, 403, 505, 608, 721 , 803), to a third network node (105), information indicating that the second network node (103) is overloaded and information indicating the identity of the second network node (103), so as to enable the third network node (105) to control the overload of the second network node (103).

2. The method according to claim 1 , further comprising:

receiving (200, 300, 400, 500, 800), from the third network node (105), information indicating that the third network node (105) supports receipt of overload information and that the third network node (105) is capable of controlling the overload of the second network node (103).

3. The method according to any one of claims 1 -2, further comprising:

during a Packet Data Network, PDN, connection creation procedure, transmitting (301 , 703, 710, 801 ), to the third network node (105), information indicating the identity of the second network node (103) and information indicating the created PDN connection associated with the second network node (103).

4. The method according to any one of claims 1 -2, further comprising:

during an Internet Protocol-Connectivity Access Network, IP-CAN, procedure for a Packet Data Network, PDN, connection, transmitting (501 , 802), to the third network node (105), information indicating the identity of the second network node (103) and information indicating the PDN connection associated with the second network node (103).

5. The method according to any one of claims 3-4, and wherein the information indicating the PDN connection is at least one of an Access Point Name, APN, and an Internet

Protocol, IP, address.

6. The method according to any one of claims 1 -5, wherein the information indicating the identity of the second network node (103) is one of an explicit identity of the second network node (103), an index indicating the identity of the second network node (103), a Tunnel Endpoint IDentifier-Control plane, TEID-C, range, a International Mobile

Subscriber Identity Number Series, I MSI NS, a Mobile Subscriber Integrated Services

Digital Network number series, MSISDN, and a charging characteristic.

7. The method according to any one of claims 1 -6, wherein the first network node (101 ) itself detects that the second network node (103) is overloaded; or

wherein the first network node (101 ) detects that the second network node (103) is overloaded by receiving information indicating the overload from the second network node (103).

8. The method according to any one of claims 1 -7, wherein the information indicating that the second network node (103) is overloaded comprises information indicating how much the third network node (103) should reduce its signaling traffic towards the second

network node to control the overload of the second network node (103).

9. The method according to any one of claims 1 -8, wherein the first network node may (101 ) is represented by a PGW or a GGSN, the second network node (103) is represented by a Policy and Charging Rules Function, PCRF, a Policy and Charging Enforcement Function, PCEF, an Online Charging System, OCS, or a Radius Server and the third network node (101 ) is represented by a Mobility Management Entity, MME,, a Serving General packet radio service Support Node, SGSN, an evolved Packet Data Gateway, ePDG, a Trusted Wireless local area network Access Network, TWAN; or a Serving GateWay, SGW; or

wherein the first network node (101 ) is represented by a PGW or a GGSN, the second network node (103) is represented by a MME, a SGSN, an ePDG, a TWAN or a SGW and the third network node (101 ) is represented by one of a PCRF, PCEF, OCS or Radius Server.

10. A method in a third network node (105) for handling overload of a second network node (103) in a communications network (100), the method comprising:

receiving (203, 305, 403, 505, 608, 721 , 1007) information, from a first network node (105), information indicating that the second network node (103) is overloaded and information indicating the identity of the second network node (103);

obtaining (204, 306, 404, 506, 1008) information indicating at least one Packet Data Network, PDN, connection associated with the identity of the second network node (103); and

determining (205, 307, 405, 507, 1009) to apply overload control towards the second network node and the associated at least one PDN connection for which information has been obtained.

1 1. The method according to claim 10, further comprising:

transmitting (200, 300, 400, 500, 1000), to the first network node (101 ), information indicating that the third network node (105) supports receipt of overload information and that the third network node (105) is capable of controlling the overload of the second network node (103).

12. The method according to any one of claims 10-1 1 , further comprising:

during a Packet Data Network, PDN, connection creation procedure, receiving

(301 , 703, 710, 1001 ), from the first network node (101 ), information indicating the identity of the second network node (103);

obtaining (301 , 1002) information indicating the created PDN connection associated with the second network node (103); and

storing (302, 1003) the received information indicating the identity of the second network node (103) and information indicating the created PDN connection associated with the second network node (103).

13. The method according to any one of claims 10-12, further comprising:

during an Internet Protocol-Connectivity Access Network, IP-CAN, procedure for a

Packet Data Network, PDN, connection, receiving (501 , 1004), from the first network node (101 ), information indicating the identity of the second network node (103);

obtaining (501 , 1005) information indicating the PDN connection associated with the second network node (103); and

storing (502, 1006) the received information indicating the identity of the second network node (103) and information indicating the PDN connection.

14. The method according to any one of claims 12-13, wherein the obtaining (204, 306, 404, 506, 1008) information indicating at least one Packet Data Network, PDN,

connection associated with the identity of the second network node (103) further

comprises:

obtaining (306, 506, 1008a) information indicating the at least one PDN connection associated with the identity of the second network node (103) from the stored information.

15. The method according to any one of claims 12-14, wherein the information indicating the PDN connection is at least one of an Access Point Name, APN, and an Internet

Protocol, IP, address.

16. The method according to any one of claims 10-15, further comprising:

transmitting (206, 308, 406, 508, 610, 1010) controlled signaling traffic to the second network node (103) as determined.

17. The method according to any one of claims 9-14, wherein the information indicating the identity of the second network node (103) is one of an explicit identity of the second network node (103), an index indicating the identity of the second network node (103), a Tunnel Endpoint IDentifier-Control plane, TEID-C, range, a International Mobile

Digital Network number, MSISDN and a charging characteristic.

18. The method according to any one of claims 10-17, wherein the information indicating that the second network node (103) is overloaded comprises information indicating how much the third network node (103) should reduce its signaling traffic towards the second network node (103) to control the overload of the second network node (103).

19. The method according to any one of claims 10-18, wherein

the first network node (101 ) is represented by a PGW or a GGSN, the second network node (103) is represented by a Policy and Charging Rules Function, PCRF, a Policy and Charging Enforcement Function, PCEF, and Online Charging System, OCS, or a Radius Server and the third network node (101 ) is represented by a Mobility Management Entity, MME, a Serving General packet radio service Support Node, SGSN, an evolved Packet Data Gateway, ePDG, a Trusted Wireless local area network Access Network, TWAN, or a Serving GateWay, SGW; or wherein the first network node (101 ) is represented by a PGW or a GGSN, the second network node (103) is represented by a MME, a SGSN, an ePDG, a TWAN or a SGW and the third network node (101 ) is represented by one of a PCRF, PCEF, OCS or Radius Server.

20. A first network node (101 ) for handling overload of a second network node (103) in a communications network (100), the first network node (101 ) comprising:

a transmitter (901 ) adapted to detect overload of the second network node (103) 5 and then transmit, to a third network node (105), information indicating that the second network node (103) is overloaded and information indicating the identity of the second network node (103) , so as to enable the third network node (105) to control the overload of the second network node (103).

10 21. The first network node (101 ) according to claim 20, further comprising:

a receiver (903) adapted to receive, from the third network node (105), information indicating that the third network node (105) supports receipt of overload information and that the third network node (105) is capable of controlling the overload of the second network node (103).

15

22. The first network node (101 ) according to any one of claims 20-21 , wherein the transmitter (901 ) is further adapted to:

during a Packet Data Network, PDN, connection creation procedure, transmit to the third network node (105), information indicating the identity of the second network 20 node (103) and information indicating the created PDN connection associated with the second network node (103).

23. The first network node (101 ) according to any one of claims 20-22, wherein the transmitter (901 ) is further adapted to:

25 during an Internet Protocol-Connectivity Access Network, IP-CAN, procedure for a

Packet Data Network, PDN, connection, transmit, to the third network node (105), information indicating the identity of the second network node (103) and information indicating the PDN connection associated with the second network node (103).

30 24. The first network node (101 ) according to any one of claims 22-23, and wherein the information indicating the PDN connection is at least one of an Access Point Name, APN, and an Internet Protocol, IP, address.

25. The first network node (101 ) according to any one of claims 20-24, wherein the 35 information indicating the identity of the second network node (103) is one of an explicit identity of the second network node (103), an index indicating the identity of the second network node (103), a Tunnel Endpoint IDentifier-Control plane, TEID-C, range, a International Mobile Subscriber Identity Number Series, IMSI NS, a Mobile Subscriber

Integrated Services Digital Network number series, MSISDN, and a charging

characteristic.

26. The first network node (101 ) according to any one of claims 20-25, wherein the first network node (101 ) itself detects that the second network node (103) is overloaded; or wherein the first network node (101 ) detects that the second network node (103) is

overloaded by receiving information indicating the overload from the second network node (103).

27. The first network node (101 ) according to any one of claims 20-26, wherein the

information indicating that the second network node (103) is overloaded comprises

information indicating how much the third network node (103) should reduce its signaling traffic towards the second network node to control the overload of the second network node (103).

28. The first network node (101 ) according to any one of claims 20-27, wherein the first network node may (101 ) is represented by a PGW or a GGSN, the second network node (103) is represented by a Policy and Charging Rules Function, PCRF, a Policy and Charging

Enforcement Function, PCEF, an Online Charging System, OCS, or a Radius Server and the third network node (101 ) is represented by a Mobility Management Entity, MME,, a Serving General packet radio service Support Node, SGSN, an evolved Packet Data Gateway, ePDG, a Terrestrial Wide Area Network, TWAN; or a Serving GateWay, SGW; or

29. A third network node (105) for handling overload of a second network node (103) in a communications network (100), the third network node (105) comprising:

a receiver (1 101 ) adapted to receive information, from a first network node (101 ), information indicating that the second network node (103) is overloaded and information indicating the identity of the second network node (103);

an obtaining unit (1 103) adapted to obtain information indicating at least one

Packet Data Network, PDN, connection associated with the identity of the second network node (103); and a determining unit (1 105) adapted to determine to apply overload control towards the second network node and the associated at least one PDN connection for which information has been obtained.

30. The third network node (105) according to claim 29, further comprising:

a transmitter (1 108) adapted to transmit, to the first network node (101 ), information indicating that the third network node (105) supports receipt of overload information and that the third network node (105) is capable of controlling the overload of the second network node (103).

31. The third network node (105) according to any one of claims 29-30, wherein the receiver (1 101 ) is further adapted to:

during a Packet Data Network, PDN, connection creation procedure, receive, from the first network node (101 ), information indicating the identity of the second network node (103);

wherein the obtaining unit (1 103) is further adapted to:

obtain information indicating the created PDN connection associated with the second network node (103); and

wherein the third network node (105) further comprises:

a memory (1 110) adapted to store the received information indicating the identity of the second network node (103) and information indicating the created PDN connection associated with the second network node (103).

32. The third network node (105) according to any one of claims 29-31 , wherein the receiver (1 101 ) is further adapted to:

during an Internet Protocol-Connectivity Access Network, IP-CAN, procedure for a Packet Data Network, PDN, connection, receive, from the first network node (101 ), information indicating the identity of the second network node (103);

wherein the obtaining unit (1 103) is further adapted to:

obtain information indicating the PDN connection associated with the second network node (103); and

wherein the third network node (105) further comprises:

a memory (1 110) adapted to store the received information indicating the identity of the second network node (103) and information indicating the PDN connection.

33. The third network node (105) according to any one of claims 29-32, wherein the obtaining unit (1103) is further adapted to: obtain information indicating the at least one PDN connection associated with the identity of the second network node (103) from the stored information.

34. The third network node (105) according to any one of claims 29-33, wherein the

5 information indicating the PDN connection is at least one of an Access Point Name, APN, and an Internet Protocol, IP, address.

35. The third network node (105) according to any one of claims 29-34, further

comprising:

10 a transmitter (1 108) adapted to transmit controlled signaling traffic to the second

network node (103) as determined.

36. The third network node (105) according to any one of claims 29-35, wherein the

information indicating the identity of the second network node (103) is one of an explicit

15 identity of the second network node (103), an index indicating the identity of the second

network node (103), a Tunnel Endpoint IDentifier-Control plane, TEID-C, range, a

International Mobile Subscriber Identity Number Series, IMSI NS, a Mobile Subscriber

Integrated Services Digital Network number, MSISDN and a charging characteristic.

20 37. The third network node (105) according to any one of claims 29-36, wherein the

information indicating how much the third network node (103) should reduce its signaling traffic towards the second network node (103) to control the overload of the second

network node (103).

25

38. The third network node (105) according to any one of claims 29-37, wherein

the first network node may (101 ) is represented by a PGW or a GGSN, the second network node (103) is represented by a Policy and Charging Rules Function, PCRF, a Policy and Charging Enforcement Function, PCEF, and Online Charging System, OCS, or a Radius Server

30 and the third network node (101 ) is represented by a Mobility Management Entity, MME, a Serving General packet radio service Support Node, SGSN, an evolved Packet Data Gateway, ePDG, a Terrestrial Wide Area Network, TWAN, or a Serving GateWay, SGW; or

wherein the first network node (101 ) is represented by a PGW or a GGSN, the second network node (103) is represented by a MME, a SGSN, an ePDG, a TWAN or a SGW and the third

35 network node (101 ) is represented by one of a PCRF, PCEF, OCS or Radius Server.