Patent Publication Number: US-11394811-B2

Title: Redirection handling

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
     This application is a 35 U.S.C. § 371 National Phase of PCT/EP2019/053572, filed Feb. 13, 2019, designating the United States, which claims the benefit of U.S. Provisional Application No. 62/630,901, filed Feb. 15, 2018, the disclosure of which are incorporated by this reference. 
    
    
     TECHNICAL FIELD 
     Embodiments herein relate to supporting redirection based on response codes and timeout under CP and UP separation. 
     BACKGROUND 
       FIG. 1  shows the architecture reference model in the case of separation between control plane and user plane.  FIG. 1  is from 3GPP TS 23.214 V15.1.0 (2017 December). This architecture reference model covers non-roaming as well as home routed and local breakout roaming scenarios. Using other words, the  FIG. 1  illustrates the architecture for GTP-based interfaces when SGW, PGW and TDF control and user planes are separated. 
     The -C or -U suffix appended to S 2 a, S 2 b, S 5  and S 8  existing reference points only indicate the control plane and user plane components of those interfaces. 
     The architecture in  FIG. 1  only depicts the case when the CP and UP functions of all SGW, PGW and TDF nodes are split. However, the other cases when the CP and UP function of only one of these nodes is split while the CP and UP function of the other interfacing node is not split, e.g. PGW&#39;s control plane and user plane is split while SGW&#39;s control plane and user plane is not split, are also supported. The split architecture of a node does not put any architectural requirements on the peer nodes with which it interfaces. TDF may be an optional functional entity. 
     For a roaming architecture with local breakout, the Gx interface is defined between the PGW-C and PCRF in the visited network. 
       FIG. 2  illustrates an example of a combined SGW/PGW architecture in the case of separation between control plane and user plane.  FIG. 2  is also from 3GPP TS 23.214 V15.1.0 (2017 December). 
     The usage of a combined SGW/PGW remains possible in a deployment with separated control and user planes. This is enabled by supporting an Sx interface with a common parameter structure for non-combined and combined cases.
         Sxa: Reference point between SGW-C and SGW-U.   Sxb: Reference point between PGW-C and PGW-U.   Sxc: Reference point between TDF-C and TDF-U.       

     3GPP TS 29.244 V14.1.0 (2017 September) subclause 5.4.7 states “Traffic Redirection refers to the process of redirecting uplink application traffic” and subclause 8.2.20 specifies Sx interface support for Redirection. These subclauses are reproduced below: 
     “5.4.7 Traffic Redirection 
     Traffic Redirection refers to the process of redirecting uplink application traffic, in a PGW or TDF, towards a redirect destination, e.g. redirect some HTTP flows to a service provisioning page. See subclause 6.1.13 of 3GPP TS 23.203 [7] and subclauses 4.5.2.6 and 4b.5.1.4 of 3GPP TS 29.212 [8]. 
     The redirect destination may be provided by the PCRF or be preconfigured in the CP function or in the UP function. 
     The traffic redirection may be enforced in the CP function or in the UP function. If the traffic that the UP function can support may be subject to traffic redirection, traffic redirection enforcement in the UP function shall be supported by the UP function. The UP function reports to the CP function whether it supports traffic redirection enforcement in the UP function via the UP Function Features IE (see subclause 8.2.25). 
     NOTE: A UP function that supports traffic not requiring traffic redirection does not need to support traffic redirection enforcement in the UP function. The CP function can select a UP function supporting traffic redirection enforcement in the UP function for users or services which may require traffic redirection. 
     To enforce the traffic redirection in the CP function, the CP function shall instruct the UP function to forward the applicable user traffic to the CP function, as specified in subclause 5.3.1. 
     To enforce the traffic redirection in the UP function, the CP function shall:
         create the necessary PDR(s) to represent the traffic to be redirected, if not already existing;   create a FAR with:   the Redirect Information IE including the redirect destination, if the traffic needs to be redirected towards a redirect destination provided by the CP function; a redirect destination provided by the CP function shall prevail over a redirect destination preconfigured in the UP function; or   the Forwarding Policy IE including the identifier of the forwarding policy to apply, if the traffic needs to be redirected towards a redirect destination preconfigured in the UP function;   associate the FAR to the above PDRs of the Sx session.”
 
“8.2.20 Redirect Information
       

     Redirect Information is coded as depicted in  FIG. 9 . 
     Redirect Address Type indicates the type of the Redirect Address. It shall be encoded as defined in Table 8.2.20-1. 
     
       
         
           
               
             
               
                 TABLE 8.2.20-1 
               
             
            
               
                   
               
               
                 Redirect Address Type 
               
            
           
           
               
               
               
            
               
                   
                   
                 Value 
               
               
                   
                 Redirect Address Type 
                 (Decimal) 
               
               
                   
                   
               
               
                   
                 IPv4 address 
                 0 
               
               
                   
                 IPv6 address 
                 1 
               
               
                   
                 URL 
                 2 
               
               
                   
                 SIP URI 
                 3 
               
               
                   
                 Spare, for future use. 
                 4 to 15 
               
               
                   
                   
               
            
           
         
       
     
     The Redirect Server Address Length shall indicate the length of the Redirect Server Address. 
     The Redirect Server Address shall be encoded in UTF8String format and shall contain the address of the redirect server (e.g. HTTP redirect server, SIP server) with which the end user is to be connected, as specified in subclauses 8.38 and 8.39 of IETF RFC 4006 [16].” 
     As seen in the above reproduced sections from 3GPP TS. 29.244, it has only specified support for Redirection triggered when the uplink request is received, Therefore, there is a need to at least mitigate or solve this issue. 
     SUMMARY 
     An objective of embodiments herein is therefore to obviate at least one of the above disadvantages and to provide improved redirection. 
     Accordingly, in one aspect there is provided a method performed by a user plane, UP, which method includes the UP determining whether a redirect message should be sent to a user equipment, UE, that has transmitted a first message intended for a first server, wherein the determining comprises: i) receiving a message transmitted by the first server and determining, based on the message, whether a redirect message should be sent to the UE or ii) detecting a timeout with respect to the first server. The method also includes the UP sending to the UE the redirect message as a result of the UP determining that redirect message should be sent to the UE. The redirect message is configured to cause the UE to send a second message to a second server. 
     In some embodiments, the method also includes the UP receiving a redirection rule transmitted by a control plane, CP. 
     In some embodiments, determining whether a redirect message should be sent to the UE comprises receiving the message transmitted by the first server and determining whether the message includes a redirection parameter that matches any redirection parameter included in a set of one or more redirection parameters, and, if the message includes a redirection parameter that matches any redirection parameter included in the set of one or more redirection parameters, then it is determined that the redirection should be sent to the UE. 
     In some embodiments, the set of redirection parameters include a set of one or more HTTP status codes. 
     In some embodiments, the set of HTTP status codes comprises status codes that begin with the digit 4 and/or status codes that begin with the digit 5. 
     In some embodiments, determining whether the message includes a redirection parameter that matches any redirection parameter included in a set of one or more redirection parameters comprises determining whether the redirection parameter included in the message matches any of the HTTP status codes included in the set of HTTP status codes. 
     In some embodiments, the redirect message is an HTTP message that includes a 302 status code and a URI pointing to the second server. 
     In some embodiments, receiving the redirection rule comprises receiving a message comprising the redirection rule, wherein the message is: an Sx Session Establishment Request message, an Sx Session Establishment Response message, an Sx Session Modification Request message, or an Sx Session Modification Response message. 
     In some embodiments, the redirection rule is a downlink, DL, Packet Detection Rule, PDR, that contains: packet detection information, PDI, and a forwarding action rule, FAR, identifier for identifying a FAR. 
     In some embodiments, the method comprises receiving a message transmitted by the first server and determining, based on the received message, whether a redirect message should be sent to the UE. Receiving the message transmitted by the first server comprises receiving DL traffic transmitted by the first server. The DL traffic comprises the message, and the method further comprises determining whether the DL traffic matches the DL PDR and activating the FAR as a result of determining that the DL traffic matches the DL PDR. 
     In some embodiments, the FAR includes an address of the second server. 
     In some embodiments, the method also includes the UP sending, to the CP, an indication that the UP supports traffic redirection triggered by a redirection parameter. In some embodiments, sending the indication to the CP comprises the UP sending to the CP a message comprising a UP Function Features Information Element (IE) comprising the indication. 
     Embodiments herein afford many advantages, of which a non-exhaustive list of examples follows: 
     An advantage of the embodiments herein is that they provide a standard way to support redirection based on response codes or timeout so that the UE&#39;s traffic can be redirected when the server is not able to provide the requested service. In this scenario the server may either return an error code or not respond at all. 
     Another advantage of the embodiments herein is that the redirection based on response codes or timeout may be activated by the Control Plane with the required granularity, e.g. per user session. 
     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: 
         FIG. 1  is a schematic block diagram illustrating an example of an architecture reference model in the case of separation between control plane and user plane. 
         FIG. 2  is a schematic block diagram illustrating an example of the architecture reference model for a combined SGW/PGW in the case of separation between control plane and user plane. 
         FIG. 3  is a schematic block diagram illustrating a communication system. 
         FIG. 4  is a sequence diagram illustrating an example of a method. 
         FIG. 5  is a sequence diagram illustrating an example of a method. 
         FIG. 6  is a flow chart illustrating an example of a session establishment procedure. 
         FIG. 7  is a flow chart illustrating an example of a session modification procedure. 
         FIG. 8  is a schematic block diagram illustrating an example of a UP. 
         FIG. 9  shows redirect information. 
         FIG. 10  shows redirect information. 
         FIG. 11  shows UP function features. 
     
    
    
     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 
     The embodiments herein relate to an Sx protocol extension to support redirection based on a redirection parameter, e.g. response codes or timeout. 
     As mentioned earlier, 3GPP TS 29.244 V14.1.0 (2017 September) has only specified support for Redirection triggered when the uplink request is received. However, it is NOT specified over Sx interface when Control Plane and User Plane are separated. Nor is it specified how to support Redirection triggered by a response code or by timeout. The response code may be for example an error code. 
       FIG. 3  depicts a communications system  100  in which embodiments herein may be implemented. The figure illustrates a User Equipment (UE)  101 . The UE  101  may be a device by which a subscriber may access services offered by an operator&#39;s network and services outside operator&#39;s network to which the operators radio access network and core network provide access, e.g. access to the Internet. The UE  101  may be any device, mobile or stationary, enabled to communicate in the communications network, for instance but not limited to e.g. user equipment, mobile phone, smart phone, sensors, meters, vehicles, household appliances, medical appliances, media players, cameras, Machine to Machine (M2M) device, Device to Device (D2D) device, Internet of Things (IoT) device or any type of consumer electronic, for instance but not limited to television, radio, lighting arrangements, tablet computer, laptop or Personal Computer (PC). The UE  101  may be portable, pocket storable, hand held, computer comprised, or vehicle mounted devices, enabled to communicate voice and/or data, via the radio access network, with another entity, such as another UE or a server. 
     The UE  101  is adapted to be connected to the User Plane (UP)  103 . The UP  103  may be represented by a user plane entity, a user plane function, a SGW-U, a PGW-U a TDF-U etc. The term UP will be used herein when referring to any entity located in the user plane. 
     The UP  103  is adapted to be connected to a User Plane (CP)  105 . The CP  105  may be represented by a control plane entity, a control plane function, a SGW-C, a PGW-C a TDF-C etc. The term UP will be used herein when referring to any entity located in the control plane. 
     The UP  103  and the CP  105  may be separate standalone entities or they may be co-located. The co-location is illustrated with the dotted box in  FIG. 1 . 
     The UP  103  is adapted to be connected to a first server (S 1 )  108  and a second server (S 2 )  110 . The first server  108  may be a first Application Server (AS) and the second server  110  may be a second AS. 
     Note that there may be additional entities in the communications system  100  which are not illustrated in  FIG. 3  for the sake of simplicity. For example, there may be a Radio Access Network (RAN) located between the UE  101  and the UP  103 . 
     It should be noted that the communication links in the communications system  100  may be of any suitable kind including either a wired or wireless link. The link may use any suitable protocol depending on type and level of layer (e.g. as indicated by the OSI model) as understood by the person skilled in the art. 
     The embodiments herein propose a mechanism to add Sx support for Redirection triggered by a response code or by timeout, as follows: 
     The UP  103  indicates to the CP  105 , e.g. through the Sx interface, support for the capability of Redirection triggered by a response code or by timeout. The timeout may be in the form of a timer, a timeout value, a timer value, a timer having a certain duration etc. This may be done through PFCP Association procedure, e.g. Setup and/or Update, by adding a new capability for Redirection triggered by a response code or by timeout in the “UP Function Features” IE as follows, the new capability is on the last row in the Table 1 UP Function Features below and with bold fonts: 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 UP Function Features 
               
            
           
           
               
               
               
               
            
               
                 Feature 
                   
                   
                   
               
               
                 Octet/Bit 
                 Feature 
                 Interface 
                 Description 
               
               
                   
               
               
                 5/1 
                 BUCP 
                 Sxa 
                 Downlink Data Buffering in CP 
               
               
                   
                   
                   
                 function is supported by the UP 
               
               
                   
                   
                   
                 function. 
               
               
                 5/2 
                 DDND 
                 Sxa 
                 The buffering parameter ‘Downlink 
               
               
                   
                   
                   
                 Data Notification Delay’ is supported 
               
               
                   
                   
                   
                 by the UP function. 
               
               
                 5/3 
                 DLBD 
                 Sxa 
                 The buffering parameter ‘DL 
               
               
                   
                   
                   
                 Buffering Duration’ is supported by 
               
               
                   
                   
                   
                 the UP function. 
               
               
                 5/4 
                 TRST 
                 Sxb, Sxc 
                 Traffic Steering is supported by the 
               
               
                   
                   
                   
                 UP function. 
               
               
                 5/5 
                 FTUP 
                 Sxa, Sxb 
                 F-TEID allocation/release in the UP 
               
               
                   
                   
                   
                 function is supported by the UP 
               
               
                   
                   
                   
                 function. 
               
               
                 5/6 
                 PFDM 
                 Sxb, Sxc 
                 The PFD Management procedure is 
               
               
                   
                   
                   
                 supported by the UP function. 
               
               
                 5/7 
                 HEEU 
                 Sxb, Sxc 
                 Header Enrichment of Uplink traffic 
               
               
                   
                   
                   
                 is supported by the UP function. 
               
               
                 5/8 
                 TREU 
                 Sxb, Sxc 
                 Traffic Redirection Enforcement in 
               
               
                   
                   
                   
                 the UP function is supported by the 
               
               
                   
                   
                   
                 UP function. 
               
               
                 6/1 
                 EMPU 
                 Sxa, Sxb 
                 Sending of End Marker packets 
               
               
                   
                   
                   
                 supported by the UP function. 
               
               
                 6/2 
                 TRRU 
                 Sxb, Sxc 
                 Traffic Redirection triggered by a 
               
               
                   
                   
                   
                 response code or timeout 
               
               
                   
                   
                   
                 Enforcement is supported by the UP 
               
               
                   
                   
                   
                 function. 
               
               
                   
               
               
                 Feature Octet/Bit: The octet and bit number within the Supported-Features IE, e.g. “5/1”. 
               
               
                 Feature: A short name that can be used to refer to the octet/bit and to the feature. 
               
               
                 Interface: A list of applicable interfaces to the feature. 
               
               
                 Description: A clear textual description of the feature. 
               
            
           
         
       
     
     When CP creates/updates an Sx session, CP indicates UP to activate Redirection triggered by a response code or by timeout. There may be different alternatives to do this. Two alternative solutions are exemplified herein, referred to as alternative 1 and alternative 2. However, first the method will be described with reference to  FIG. 4 : 
     A method according to some embodiments will now be described with reference to the combined signalling diagram and flowchart depicted in  FIG. 4 . The method comprises the following steps, which steps may as well be carried out in another suitable order than described below. 
     Step  401   
     The UP  103  may send, to the CP  105 , an indication of that the UP supports the traffic redirection triggered by a redirection parameter. The redirection parameter may be a response code or a timeout. The response code may be for example an error code or a status code etc. The timeout may also be referred to as a timer associated with no receipt of a response. 
     Step  402   
     The UP  103  receives, from the CP  105 , instructions to activate Redirection triggered by a redirection parameter. 
     Step  403   
     The UP  103  receives, from the first server  108 , a message comprising a redirection parameter. 
     Step  404   
     Triggered by the received message in step  403 , the UP  103  determines that the traffic should be redirected. 
     Step  405   
     The UP  103  redirects traffic. The redirection is done by the UP  103  sending a redirect message to the UE  101  with the redirection parameter received from the first server. The redirect message indicates that traffic should be redirected to the second server  110  according to the redirection parameter. The UP  103  may determine to redirect the traffic when the message from the first server  108  has been detected. 
     If timeout happens, it means that no message is received from the first server  108  in a long time, nothing received within the time set by a timer. 
     Now continuing to the two alternatives mentioned earlier, i.e. alternative 1 and alternative 2. 
     Alternative 1: 
     The UP  103  triggers a Redirect message to the second server  110  in step  505  at detection of a message from the first server  108  with a certain redirection parameter, e.g. with certain response code/s, e.g. typically error codes like 4xx or 5xx, or at timeout, e.g. waiting for a response from the first server. A new TCP connection will be established between the UE  101  and the second server  110 , and the old TCP connection between the UE  101  and the first server  108  may be terminated or unused. This is shown in  FIG. 5  where the UP  103  is represented by a PGW UP, the CP  105  is represented by a PGW CP. The first server  108  is represented by a first AS and the second server  110  is represented by a second AS. 
     The method for alternative 1 illustrated in  FIG. 5  comprises at least one of the following steps, which steps may be performed in any suitable order than described below: 
     Step  501   
     This may be an optional step. A TRRU Redirect capability may be exchanged between the CP and the UP. The UP  103  may report to the CP  105  the capability of Redirection triggered by redirection parameter, e.g. a response code or by timeout. This step  501  may be seen as a precondition. As an alternative, the CP  110  may assume, without receiving any such report, that the UP  103  has this capability. 
     Step  502   
     The CP  105  sends a message to the UP  103 . The message may be an Sx Request message. The message may be an Sx Establishment Request message (as illustrated in  FIG. 5 ) or it may be an Sx session Creation Request or it may be an Sx Session Modification Request message. 
     At the Sx Request, the CP will activate a DL PDR (to match DL traffic) associated to a FAR. In other words, the DL PDR is included in the message sent from the CP  105  to the UP  103  in step  502 . The FAR includes a Forwarding Policy IE, which has a Redirect forwarding policy. The specifics of this Redirect forwarding policy may be locally configured in the UP  103 , e.g. including the specific redirection parameter, e.g. response codes or timeout, to trigger this type of redirection. These response codes may be for example error codes 4xx, 5xx. Similarly, the specific timeout value may also be assumed to be locally configured in the UP  103 , and may have the value of e.g. 5 seconds. 
     The step may also involve that the UP  103  creates some of the following:
         UL PDR.   FAR, FAR 1: Apply Action IE (FORW)+Forwarding Parameters (pass).   DL PDR.   FAR, FAR 2: Apply Action IE (FORW)+Forwarding Parameters (Forwarding Policy IE with a Redirect forwarding policy).       

     The term PDR used above will now be shortly described. The CP function is responsible for instructing the UP function about how to detect user data traffic belonging to a Packet Detection Rule (PDR). The other parameters provided within a PDR describe how the UP function shall treat a packet that matches the detection information. The CP function controls the traffic detection at the UP function by providing detection information for every PDR. Detection information is a combination of:
         UE IP address;   F-TEIDu;   SDF filters   Application ID (referring to an application detection filter).
 
Step  503 
       

     The UP  103  sends an Sx Response message to the CP  105 . This is a response to the message in step  502 . The Sx response message may be an Sx Establishment Response message (as illustrated in  FIG. 5 ) or it may be an Sx session Creation Response or it may be an Sx Session Modification Response message. 
     Step  504   
     Synchronization takes place between the UE  101  and the first server  108 . 
     Step  505   
     The UE  101  sends a request message to the first server  108 . 
     Step  506   
     The UP  103  receives message from the first server  108 . The message may be a response message. The message may comprise the redirection parameter, e.g. a timeout or response code. The response code may be in the form of an error code. In other words, a timeout or the response code has happened. 
     Step  506   a    
     The UE  101  sends user traffic, e.g. HTTP GET, to the UP  103 . The user traffic may be referred to as UL traffic or UL packets. 
     Step  507   
     The UP  103  performs packet processing message from step  506 . The packet processing may comprise to find the redirect destination in UP configuration. Using other words, this packet processing may involve that the UP  103  determines that the packet matches the DL PDR above from step  502 . As this DL PDR is associated to a FAR which includes a Redirect forwarding policy (as described in step  502  above), the UP  103  will check if the received redirection parameter matches the locally configured redirection parameter in the UP  103 . For example, the UP  103  checks if the received response code, e.g.  401 , matches with any of the locally configured response codes. 
     Step  508   
     If there is a match in step  507 , redirection will be triggered by means of generating a Redirect response message which is sent from the UP  103  to the UE  101 , and by dropping the previously received downlink packet, e.g.  401 . Additionally, the TCP connection between the UE  101  and the first server  108  will be closed. The response message in step  508  may be a response to the request message in step  505 . 
     Step  509   
     The UP  103  may send an acknowledgement message to the first server  108 . 
     Step  510   
     The UP  103  may send a FIN message to the UE  101 . 
     Step  511   
     The UP  103  may send a RST message to the first server  108 . 
     Step  512   
     The UP  103  performs packet processing. 
     Step  513   
     User traffic is sent between the second server  110  and the UE  101 . 
     As mentioned above, the Sx message sent in  FIG. 5  may be an Sx Session Establishment procedure or it may be an Sx session Creation procedure or an Sx Session Modification procedure. These two procedures will now be shortly described. 
       FIG. 6  illustrates an Sx session establishment procedure as in the prior art disclosed by 3GPP TS 23.214 V15.1.0 (2017 December). The procedure illustrated in  FIG. 6  comprises at least one of the following steps:
         1) CP function receives the trigger to establish a new PDN connection or TDF session from a peer CP function, an MME or a PCRF.   2) The CP function sends an Sx session establishment request message to the UP function that contains the structured control information which defines how the UP function needs to behave.   3) The UP function responds with an Sx session establishment response message containing any information that the UP function has to provide to the CP function in response to the control information received.   4) The CP function interacts with the network entity which triggered this procedure (e.g. a peer CP function, an MME or a PCRF).       

     In case of a TDF in unsolicited reporting mode, the procedure is triggered by TDF configuration and step 1 and 4 may not apply. 
     Note that the messages illustrated in  FIG. 6  comprise additional messages as described above with reference to  FIGS. 4 and 5 . 
       FIG. 7  illustrates an Sx session modification procedure as in the prior art disclosed by 3GPP TS 23.214 V15.1.0 (2017 December). The Sx session modification procedure is used to update the Sx session context of an existing PDN connection, IP-CAN session, TDF session or TDF in unsolicited reporting mode at the UP function. The Sx session modification procedure is executed between SGW-C and SGW-U whenever PDN connection related parameters have to be modified, as well as between PGW-C and PGW-U whenever PDN connection or IP-CAN session related parameters have to be modified. The Sx session modification procedure is executed between TDF-C and TDF-U whenever TDF session related parameters have to be modified. For a TDF in unsolicited reporting mode, the Sx session modification procedure is executed between TDF-C and TDF-U whenever instructions for application detection and reporting have to be modified. 
     The procedure illustrated in  FIG. 7  comprises at least one of the following steps:
         1) CP function receives the trigger to modify the existing PDN connection or TDF session from a peer CP function, an MME or a PCRF.   2) The CP function sends an Sx session modification request message to the UP function that contains the update for the structured control information which defines how the UP function needs to behave.   3) The UP function identifies the Sx session context to be modified by the Session ID. Then, the UP function updates the parameters of this Sx session context according to the list of parameters sent by the CP function. The UP function responds with an Sx session modification response message containing any information that the UP function has to provide to the CP function in response to the control information received.   4) The CP function interacts with the network entity which triggered this procedure (e.g. a peer CP function, an MME or a PCRF).       

     In case of a TDF in unsolicited reporting mode, the procedure is triggered by TDF configuration and step 1 and 4 do not apply. 
     Alternative 2: 
     In alternative 2, the UP  103  acts as a HTTP proxy acting as server to UE, and as client to the first and second servers  108 ,  110 . Once the UP detects a certain redirection parameter, e.g. a response code, in the HTTP response message, e.g. typically error codes like 4xx or 5xx, a new FAR will be activated. This FAR will indicate that upon subsequent UL traffic detected by the same UL PDR rule, the UP  103  will redirect the traffic to the second server  110  according to Redirection Information IE. The method for alternative 2 comprises at least one of the following steps, which steps may be performed in any suitable order than described below: 
     Step  701   
     As a precondition, UP has reported to CP the capability of Redirection triggered by a redirection parameter. The redirection parameter may be for example a response code or a timeout. 
     Step  702   
     At Sx Session Request, the CP will provision:
         DL PDR, requiring UP function to retrieve redirection parameter. For example to retrieve the HTTP response/status code or to monitor if the request has timeout. This DL PDR will have an associated FAR, to forward DL traffic to the UE/SGW, and should have extra information to instruct UP to replace the e.g. 4xx or 5xx response/status code with the  302  status code and to include the Redirect URI (pointing to S 2 ) in Location header. The timeout is for the user traffic, e.g. HTTP GET.   UL PDR with two associated FARs:
           A first FAR to send UL traffic via the SGi to an external network.   A second FAR to redirect. This second FAR is not active until the redirection parameter match is detected, e.g. until a response or timeout is detected. Once such response/status code is matched or timeout is detected, the corresponding UL PDR shall be linked to this second FAR to redirect UE to S 2 .   
               

     The SGi mentioned above is an interface between a gateway and an external network, for example between the PGW and a PDN, between the PGW-U and a PDN, a UP and the PDN etc. 
     The Sx Session Request may be Sx Session Establishment Request or it may be an Sx session Creation Request or Sx Session Modification Request. 
     Step  703   
     The UP  103  receives a DL packet matching the DL PDR above, e.g.  401  error status code. At this time, the second FAR described above will be activated. 
     Step  704   
     The UP  103  receives a subsequent UL packet matching the UL PDR described above. Redirection will be triggered by means of generating a Redirect response message towards the UE  101 . 
     To perform the method steps described above, the UP  103  may comprises an arrangement as shown in  FIG. 8 . 
     The UP may be arranged to, e.g. by means of a transmitter  801 , send, to the Control Plane, CP, an indication of that the UP supports the traffic redirection triggered by redirection parameter. 
     The UP  103  may be arranged to, e.g. by means of a receiver  803 , receive, from the CP, instructions to activate Redirection triggered by a redirection parameter. 
     The UP  103  may be arranged to, e.g. by means of the receiver  803 , receive, from the first server (S 1 ), a message comprising a redirection parameter. 
     The UP  103  may be arranged to, e.g. by means of a processor  805 , determine to redirect the traffic. 
     The UP  103  may be arranged to, e.g. by means of the transmitter  801 , when the message from the first server (S 1 ) has been detected, redirect ( 308 ) traffic by sending a redirect message to the UE with the redirection parameter from the first server. The redirect message indicates that traffic should be redirected to the second server (S 2 ) according to the redirection parameter. 
     The UP may be arranged to:
         send, e.g. by means of the transmitter  801 , to the Control Plane, CP, an indication of that the UP supports the traffic redirection triggered by the redirection parameter;   receive, e.g. by means of the receiver  803 , an Sx Session Request message from the CP, wherein the Sx Session Request message comprises a DL PDR to match traffic, wherein the DL PDR is associated with a Redirect forwarding policy, and wherein redirection parameter associated with the Redirect forwarding policy are locally configured in the UP;   receive, e.g. by means of the receiver  803 , a DL packet from the first server (S 1 ) which matches the DL PDR, wherein the DL packet comprises the redirection parameter;   check, e.g. by means of the processor  805 , if the redirection parameter in the received DL packet matches any of the locally configured redirection parameter;   when there is a match of redirection parameter, send, e.g. by means of the transmitter  801 , a redirect message to the UE and dropping the received DL packet.       

     The UP may be arranged to:
         send, e.g. by means of the transmitter  801 , to the Control Plane, CP, an indication of that the UP supports the traffic redirection triggered by the redirection parameter;   receive, e.g. by means of the receiver  803 , an Sx Session Request message from the CP, wherein the Sx Session Request message comprises a DL PDR associated with a first FAR, wherein the DL PDR indicates to the UP to evaluate the redirection parameter, e.g. to retrieve a response code or to monitor if the Sx Session Request message has timed out;   receive, e.g. by means of the receiver  803 , DL traffic matching the DL PDR from the first server (S 1 );   activate, e.g. by means of the processor  805 , the second FAR when the matching DL traffic is received;   redirect, e.g. by means of the processor  805 , subsequent UL traffic to the S 2 .       

     In some embodiments, the UP  101  comprises the processor  805  and a memory  810 . The memory  810  comprises instructions executable by the processor  805 . The memory  805  is arranged to be used to store data, received data streams, power level measurements, messages, the redirection parameter, response codes, timer, timeout value, requests, responses, traffic, instructions, indications, information elements (IE), decisions, to perform the methods herein when being executed UP  101 . 
     In some embodiments, a computer program may comprise instructions which, when executed on at least one processor, cause the at least one processor to carry out the method steps described above. A carrier may comprise the computer program, and the carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium. 
     The present mechanism may be implemented through one or more processors, such as a processor  805  in the UP arrangement depicted in  FIG. 8 , 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 micro processor. 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 UP  103 . 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 can furthermore be provided as pure program code on a server and downloaded to the UP  103 . 
     The embodiments herein relate to support for DL redirection. 3GPP TS 29.244 only specifies support for Redirection triggered when the uplink request is received, but it is NOT specified how to support Redirection triggered by a redirection parameter, e.g. a response code (typically an error code) and/or by timeout over Sx interface, when Control Plane and User Plane is separated. And redirection for port number is not supported in 29.244. The embodiments herein propose to add Sx support for Redirection triggered by a redirection parameter. And redirection for port number is also included. 
     Traffic Redirection 
     Traffic Redirection refers to the process of redirecting uplink and downlink application traffic, in a PGW or TDF, towards a redirect destination, e.g. redirect some HTTP flows to a service provisioning page. 
     The redirect destination may be provided by the PCRF or be preconfigured in the CP function or in the UP function. 
     The traffic redirection may be enforced in the CP function or in the UP function. If the traffic that the UP function can support may be subject to traffic redirection, traffic redirection enforcement in the UP function shall be supported by the UP function. The UP function reports to the CP function whether it supports traffic redirection enforcement in the UP function via the UP Function Features IE. 
     A UP function that supports traffic not requiring traffic redirection does not need to support traffic redirection enforcement in the UP function. The CP function can select a UP function supporting traffic redirection enforcement in the UP function for users or services which may require traffic redirection. 
     To enforce the traffic redirection in the CP function, the CP function shall instruct the UP function to forward the applicable user traffic to the CP function. To enforce the traffic redirection in the UP function, the CP function shall:
         create the necessary PDR(s) to represent the traffic to be redirected, if not already existing;   create a FAR with:   the Redirect Information IE including the redirect destination, if the traffic needs to be redirected towards a redirect destination provided by the CP function; a redirect destination provided by the CP function shall prevail over a redirect destination preconfigured in the UP function; or   the Forwarding Policy IE including the identifier of the forwarding policy to apply, if the traffic needs to be redirected towards a redirect destination preconfigured in the UP function;   associate the FAR to the above PDRs of the Sx session.
 
Create FAR IE within Sx Session Establishment Request
       

     The Create FAR grouped IE shall be encoded as shown in Table 2. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Create FAR IE within Sx Session Establishment Request  
               
            
           
           
               
               
            
               
                 Octet 1 and 2  
                 Create FAR IE Type = 3 (decimal)  
               
               
                 Octets 3 and 4  
                 Length = n  
               
            
           
           
               
               
               
               
               
            
               
                 Information  
                   
                   
                 Appl.  
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 elements  
                 P  
                 Condition/Comment  
                 Sxa  
                 Sxb  
                 Sxc  
                 IE Type 
               
               
                   
               
               
                 FAR ID  
                 M  
                 This IE shall uniquely identify the FAR  
                 X  
                 X  
                 X  
                 FAR ID  
               
               
                   
                   
                 among all the FARs configured for that  
                   
                   
                   
                   
               
               
                   
                   
                 Sx session.  
                   
                   
                   
                   
               
               
                 Apply Action  
                 M  
                 This IE shall indicate the action to apply  
                 X  
                 X  
                 X  
                 Apply  
               
               
                   
                   
                 to the packets, See subclauses 5.2.1 and  
                   
                   
                   
                 Action  
               
               
                   
                   
                 5.2.3.  
                   
                   
                   
                   
               
               
                 Forwarding  
                 C  
                 This IE shall be present when the Apply-  
                 X  
                 X  
                 X  
                 Forwarding  
               
               
                 Parameters  
                   
                 Action requests the packets to be  
                   
                   
                   
                 Parameters  
               
               
                   
                   
                 forwarded. It may be present otherwise.  
                   
                   
                   
                   
               
               
                   
                   
                 When present, this IE shall contain the  
                   
                   
                   
                   
               
               
                   
                   
                 forwarding instructions to be applied by  
                   
                   
                   
                   
               
               
                   
                   
                 the UP function when the Apply-Action  
                   
                   
                   
                   
               
               
                   
                   
                 requests the packets to be forwarded.  
                   
                   
                   
                   
               
               
                   
                   
                 See table 7.5.2.3-2.  
                   
                   
                   
                   
               
               
                 Duplicating  
                 C  
                 This IE shall be present when the Apply-  
                 X  
                 X  
                 — 
                 Duplicating  
               
               
                 Parameters  
                   
                 Action requests the packets to be  
                   
                   
                   
                 Parameters  
               
               
                   
                   
                 duplicated. It may be present otherwise.  
                   
                   
                   
                   
               
               
                   
                   
                 When present, this IE shall contain the  
                   
                   
                   
                   
               
               
                   
                   
                 forwarding instructions to be applied by  
                   
                   
                   
                   
               
               
                   
                   
                 the UP function for the traffic to be  
                   
                   
                   
                   
               
               
                   
                   
                 duplicated, when the Apply-Action  
                   
                   
                   
                   
               
               
                   
                   
                 requests the packets to be duplicated.  
                   
                   
                   
                   
               
               
                   
                   
                 See table 7.5.2.3-3.  
                   
                   
                   
                   
               
               
                 BAR ID  
                 O  
                 When present, this IE shall contain the  
                 X  
                 — 
                 — 
                 BAR ID  
               
               
                   
                   
                 BAR ID of the BAR defining the  
                   
                   
                   
                   
               
               
                   
                   
                 buffering instructions to be applied by  
                   
                   
                   
                   
               
               
                   
                   
                 the UP function when the Apply Action  
                   
                   
                   
                   
               
               
                   
                   
                 requests the packets to be buffered.  
                   
                   
                   
                   
               
               
                   
                   
                 See table 7.5.2.6-1. 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Forwarding Parameters IE in FAR  
               
            
           
           
               
               
            
               
                 Octet 1 and 2  
                 Forwarding Parameters IE Type = 4 (decimal)  
               
               
                 Octets 3 and 4  
                 Length = n  
               
            
           
           
               
               
               
               
               
            
               
                 Information  
                   
                   
                 Appl.  
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 elements  
                 P  
                 Condition/Comment  
                 Sxa  
                 Sxb  
                 Sxc  
                 IE Type 
               
               
                   
               
               
                 Destination  
                 M  
                 This IE shall identify the destination  
                 X  
                 X  
                 X  
                 Destination  
               
               
                 Interface  
                   
                 interface of the outgoing packet.  
                   
                   
                   
                 Interface  
               
               
                 Network  
                 O  
                 When present, this IE shall identify the  
                 X  
                 X  
                 X  
                 Network  
               
               
                 Instance  
                   
                 Network instance towards which to send  
                   
                   
                   
                 Instance  
               
               
                   
                   
                 the outgoing packet. See NOTE 1.  
                   
                   
                   
                   
               
               
                 Redirect  
                 C  
                 This IE shall be present if the UP  
                 — 
                 X  
                 X  
                 Redirect  
               
               
                 Information  
                   
                 function is required to enforce traffic  
                   
                   
                   
                 Information  
               
               
                   
                   
                 redirection towards a redirect  
                   
                   
                   
                   
               
               
                   
                   
                 destination provided by the CP function.  
                   
                   
                   
                   
               
               
                 Outer Header  
                 C  
                 This IE shall be present if the UP  
                 X  
                 X  
                 — 
                 Outer Header  
               
               
                 Creation  
                   
                 function is required to add one or more  
                   
                   
                   
                 Creation  
               
               
                   
                   
                 outer header(s) to the outgoing packet.  
                   
                   
                   
                   
               
               
                   
                   
                 If present, it shall contain the F-TEID of  
                   
                   
                   
                   
               
               
                   
                   
                 the remote GTP-U peer when adding a  
                   
                   
                   
                   
               
               
                   
                   
                 GTP-U/UDP/IP header, or the  
                   
                   
                   
                   
               
               
                   
                   
                 Destination IP address and Port Number  
                   
                   
                   
                   
               
               
                   
                   
                 when adding a UDP/IP header.  
                   
                   
                   
                   
               
               
                 Transport  
                 C  
                 This IE shall be present if the UP  
                 X  
                 X  
                 — 
                 Transport Level  
               
               
                 Level  
                   
                 function is required to mark the IP  
                   
                   
                   
                 Marking  
               
               
                 Marking  
                   
                 header with the DSCP marking as  
                   
                   
                   
                   
               
               
                   
                   
                 defined by IETF RFC 2474 [22]. When  
                   
                   
                   
                   
               
               
                   
                   
                 present, it shall contain the value of the  
                   
                   
                   
                   
               
               
                   
                   
                 DSCP in the TOS/Traffic Class field set  
                   
                   
                   
                   
               
               
                   
                   
                 based on the QCI, and optionally the  
                   
                   
                   
                   
               
               
                   
                   
                 ARP priority level, of the associated  
                   
                   
                   
                   
               
               
                   
                   
                 EPS bearer, as described in sub-clause  
                   
                   
                   
                   
               
               
                   
                   
                 4.7.3 of 3GPP TS 23.214 [2].  
                   
                   
                   
                   
               
               
                 Forwarding  
                 C  
                 This IE shall be present if a specific  
                 — 
                 X  
                 X  
                 Forwarding  
               
               
                 Policy  
                   
                 forwarding policy is required to be  
                   
                   
                   
                 Policy  
               
               
                   
                   
                 applied to the packets. It shall be  
                   
                   
                   
                   
               
               
                   
                   
                 present if the Destination Interface IE is  
                   
                   
                   
                   
               
               
                   
                   
                 set to SGi-LAN. It may be present if the  
                   
                   
                   
                   
               
               
                   
                   
                 Destination Interface is set to Core or  
                   
                   
                   
                   
               
               
                   
                   
                 Access(for DL redirection).  
                   
                   
                   
                   
               
               
                   
                   
                 When present, it shall contain an  
                   
                   
                   
                   
               
               
                   
                   
                 Identifier of the Forwarding Policy  
                   
                   
                   
                   
               
               
                   
                   
                 locally configured in the UP function.  
                   
                   
                   
                   
               
               
                 Header  
                 O  
                 This IE may be present if the UP  
                 — 
                 X  
                 X  
                 Header  
               
               
                 Enrichment  
                   
                 function indicated support of Header  
                   
                   
                   
                 Enrichment  
               
               
                   
                   
                 Enrichment of UL traffic. When  
                   
                   
                   
                   
               
               
                   
                   
                 present, it shall contain information  
                   
                   
                   
                   
               
               
                   
                   
                 for header enrichment. 
               
               
                   
               
               
                 NOTE 1: 
               
               
                 The Network Instance parameter is needed e.g. in the following cases: 
               
               
                 PGW/TDF UP function supports multiple PDNs with overlapping IP addresses; 
               
               
                 SGW UP function is connected to PGWs in different IP domains (S5/S8); 
               
               
                 PGW UP function is connected to SGWs in different IP domains (S5/S8); 
               
               
                 SGW UP function is connected to eNodeBs in different IP domains. 
               
            
           
         
       
     
                     TABLE 4                  Duplicating Parameters IE in FAR                      Octet 1 and 2    Duplicating Parameters IE Type = 5 (decimal)        Octets 3 and 4    Length = n                                  Information            Appl.                                              elements    P    Condition/Comment    Sxa    Sxb    Sxc    IE Type               Destination    M    This IE shall identify the destination    X    X    —   Destination        Interface        interface of the outgoing packet.                Interface        Outer Header    C    This IE shall be present if the UP    X    X    —   Outer Header        Creation        function is required to add one or more                Creation                outer header(s) to the outgoing packet. If                                present, it shall contain the F-TEID of                                the remote GTP-U peer.                        Transport    C    This IE shall be present if the UP    X    X    —   Transport Level        Level        function is required to mark the IP                Marking        marking        header with the DSCP marking as                                defined by IETF RFC 2474 [22]. When                                present, it shall contain the value of the                                DSCP in the TOS/Traffic Class field.                        Forwarding    C    This IE shall be present if a specific    X    X    —   Forwarding        Policy        forwarding policy is required to be                Policy                applied to the packets. When present,                                it shall contain an Identifier of the                                Forwarding Policy locally configured                                in the UP function.                    
Redirect Information
 
     Redirect Information is coded as depicted in  FIG 10 . 
     Redirect Address Type indicates the type of the Redirect Address. It shall be encoded as defined in Table 5. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Redirect Address Type 
               
            
           
           
               
               
               
            
               
                   
                   
                 Value 
               
               
                   
                 Redirect Address Type 
                 (Decimal) 
               
               
                   
                   
               
               
                   
                 IPv4 address 
                 0 
               
               
                   
                 IPv6 address 
                 1 
               
               
                   
                 URL 
                 2 
               
               
                   
                 SIP URI 
                 3 
               
               
                   
                 Port 
                 4 
               
               
                   
                 Spare, for future use. 
                 5 to 15 
               
               
                   
                   
               
            
           
         
       
     
     The Redirect Server Address Length shall indicate the length of the Redirect Server Address. 
     The Redirect Server Address shall be encoded in UTF8String format and shall contain the address of the redirect server (e.g. HTTP redirect server, SIP server) with which the end user is to be connected. 
     The UP Function Features IE indicates the features supported by the UP function. It is coded as depicted in  FIG. 11 . 
     The UP Function Features IE takes the form of a bitmask where each bit set indicates that the corresponding feature is supported. Spare bits shall be ignored by the receiver. The same bitmask is defined for all PFCP interfaces. 
     The following table specifies the features defined on PFCP interfaces and the interfaces on which they apply. 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 UP Function Features 
               
            
           
           
               
               
               
               
            
               
                 Feature 
                   
                   
                   
               
               
                 Octet/Bit 
                 Feature 
                 Interface 
                 Description 
               
               
                   
               
               
                 5/1 
                 BUCP 
                 Sxa 
                 Downlink Data Buffering in CP 
               
               
                   
                   
                   
                 function is supported by the UP 
               
               
                   
                   
                   
                 function. 
               
               
                 5/2 
                 DDND 
                 Sxa 
                 The buffering parameter ‘Downlink 
               
               
                   
                   
                   
                 Data Notification Delay’ is supported 
               
               
                   
                   
                   
                 by the UP function. 
               
               
                 5/3 
                 DLBD 
                 Sxa 
                 The buffering parameter ‘DL 
               
               
                   
                   
                   
                 Buffering Duration’ is supported by 
               
               
                   
                   
                   
                 the UP function. 
               
               
                 5/4 
                 TRST 
                 Sxb, Sxc 
                 Traffic Steering is supported by the 
               
               
                   
                   
                   
                 UP function. 
               
               
                 5/5 
                 FTUP 
                 Sxa, Sxb 
                 F-TEID allocation/release in the UP 
               
               
                   
                   
                   
                 function is supported by the UP 
               
               
                   
                   
                   
                 function. 
               
               
                 5/6 
                 PFDM 
                 Sxb, Sxc 
                 The PFD Management procedure is 
               
               
                   
                   
                   
                 supported by the UP function. 
               
               
                 5/7 
                 HEEU 
                 Sxb, Sxc 
                 Header Enrichment of Uplink traffic 
               
               
                   
                   
                   
                 is supported by the UP function. 
               
               
                 5/8 
                 TREU 
                 Sxb, Sxc 
                 Traffic Redirection Enforcement in 
               
               
                   
                   
                   
                 the UP function is supported by the 
               
               
                   
                   
                   
                 UP function. 
               
               
                 6/1 
                 EMPU 
                 Sxa, Sxb 
                 Sending of End Marker packets 
               
               
                   
                   
                   
                 supported by the UP function. 
               
               
                 6/2 
                 TRRU 
                 Sxb, Sxc 
                 Traffic Redirection triggered by a 
               
               
                   
                   
                   
                 response code and/or timeout 
               
               
                   
                   
                   
                 Enforcement is supported by the UP 
               
               
                   
                   
                   
                 function. 
               
               
                   
               
               
                 Feature Octet/Bit: The octet and bit number within the Supported-Features IE, e.g. “5/1”. 
               
               
                 Feature: A short name that can be used to refer to the octet/bit and to the feature. 
               
               
                 Interface: A list of applicable interfaces to the feature. 
               
               
                 Description: A clear textual description of the feature. 
               
            
           
         
       
     
     Summarized, the embodiments herein propose to add Sx support for Redirection triggered by a response code or by timeout, specifically:
         The UP indicates to the CP (through Sx) support for the capability of Redirection triggered by a response code or by timeout.   On a per Sx session basis, the CP indicates to the UP, through Sx, to activate Redirection triggered by a response code or by timeout.       

     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. A feature from one embodiment may be combined with one or more features of any other embodiment. Also, the teachings herein are equally applicable for N4 interface between SMF and UPF. 
     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. The terms “consisting of” or “consisting essentially of” may be used instead of the term comprising. 
     The term “configured to” used herein may also be referred to as “arranged to”, “adapted to”, “capable of” or “operative to”. 
     It should also be emphasised that the steps of the methods defined herein, without departing from the embodiments herein, be performed in another order than the order in which they appear. 
     EXAMPLE EMBODIMENTS 
     Some embodiments described herein may be summarised in the following manner: 
     A method performed by a User Plane, UP, the method comprising at least one of the following steps: sending ( 301 ), to the Control Plane, CP, an indication of that the UP supports the traffic redirection triggered by a redirection parameter; receiving ( 302 ), from the CP, instructions to activate Redirection triggered by the redirection parameter; receiving ( 306 ), from the first server (S 1 ), a message comprising a redirection parameter; redirecting ( 308 ) traffic by sending a redirect message to the UE with the parameter received from the first server, wherein the redirect message indicates that traffic should be redirected to the second server (S 2 ) according to the parameter. 
     The method may further comprise: comparing the redirection parameter received from the first server with the redirection parameter received from the CP; wherein the traffic is redirected when a result of the comparing indicates that the two redirection parameters are matching or that they are substantially matching. 
     The traffic redirection is triggered by receipt of the redirection parameter. 
     The redirection parameter may be: a response code, or a timeout, or both a response code and a timeout. 
     The traffic may be redirected to a certain redirect destination. The redirect destination may be the second server. 
     It may be UL traffic or DL traffic or both UL and DL traffic that should be redirected to the redirect destination. 
     The indication of that the UP supports the traffic redirection triggered by the redirection parameter may be comprised in the UP Function Features IE. 
     The instructions to activate Redirection triggered by the redirection parameter may be sent in: an Sx Session Establishment Request message, or an Sx session Creation Response, or an Sx Session Modification Response message. 
     A method performed by a User Plane, UP, the method comprising at least one of the following steps: sending ( 501 ), to the Control Plane, CP, an indication of that the UP supports the traffic redirection triggered by the redirection parameter; receiving ( 502 ) an Sx Session Request message from the CP, wherein the Sx Session Request message comprises a DL PDR to match traffic, wherein the DL PDR is associated with a Redirect forwarding policy, and wherein the redirection parameter associated with the Redirect forwarding policy are locally configured in the UP; receiving ( 506 ) a DL packet from the first server (S 1 ) which matches the DL PDR, wherein the DL packet comprises the redirection parameter; checking ( 507 ) if the redirection parameter in the received DL packet matches the locally configured the redirection parameter; when there is a match of the redirection parameter, sending ( 508 ) a redirect message to the UE and dropping the received DL packet. 
     The DL PDR may be associated with a FAR. 
     The TCP connection between the UE and the S 1  may be closed. 
     A method performed by a User Plane, UP, the method comprising at least one of the following steps: sending ( 501 ), to the Control Plane, CP, an indication of that the UP supports the traffic redirection triggered by the redirection parameter; receiving ( 502 ) an Sx Session Request message from the CP, wherein the Sx Session Request message comprises a DL PDR associated with a first FAR, wherein the DL PDR indicates to the UP to retrieve a response code or to monitor if the Sx Session Request message has timed out; receiving DL traffic matching the DL PDR from the first server (S 1 ); activating the second FAR when the matching DL traffic is received; redirecting subsequent UL traffic to the S 2 . 
     The UL PDR may be associated with: a first FAR which indicates that UL traffic should be sent via the SGi to an external network and/or a second FAR which indicates redirection of traffic from the first server (S 1 ) to the second server (S 2 ), and/or both the first and second FAR. 
     The second FAR may be inactive until the redirection parameter math is detected, e.g. until a response code is detected or until a timeout is detected. 
     When the redirection parameter math is detected, the corresponding UL PDR may be linked to the second FAR 
     The instructions to activate Redirection triggered by the redirection parameter may be received through Sx interface. 
     The UP is a UP entity such as e.g. a User Plane Function, UPF, a gateway UP, a PGW UP, a UP proxy, a HTTP proxy, an entity acting as a server to the UE, PGW-U, TDF-U. 
     The CP is a CP entity such as a gateway CP, a PGW CP, a CP proxy, a HTTP proxy, an entity acting as a server to the UE, PGW-C or TDF-C. 
     There is a direct interface between the UP and CP so that they are adapted to communicate directly with each other. The interface may be an Sx interface. 
     CP and UP are separated. 
     A User Plane, UP, arranged to: send, to the Control Plane, CP, an indication of that the UP supports the traffic redirection triggered by response code or by timeout; receive, from the CP, instructions to activate Redirection triggered by a response code or by timeout; receive, from the first server (S 1 ), a message comprising a response code or a timeout value; when the message from the first server (S 1 ) has been detected, redirect ( 308 ) traffic by sending a redirect message to the UE with the response code or timeout value from the first server, wherein the redirect message indicates that traffic should be redirected to the second server (S 2 ) according to the response code or timeout. 
     A User Plane, UP, arranged to: send, to the Control Plane, CP, an indication of that the UP supports the traffic redirection triggered by response code or by timeout; receive an Sx Session Request message from the CP, wherein the Sx Session Request message comprises a DL PDR to match traffic, wherein the DL PDR is associated with a Redirect forwarding policy, and wherein response codes or timeout values associated with the Redirect forwarding policy are locally configured in the UP; receive a DL packet from the first server (S 1 ) which matches the DL PDR, wherein the DL packet comprises response codes or timeout value; check if the response codes or timeout value in the received DL packet matches any of the locally configured response codes or time out values; when there is a match of response codes or timeout value, send a redirect message to the UE and dropping the received DL packet. 
     A User Plane, UP, arranged to: send, to the Control Plane, CP, an indication of that the UP supports the traffic redirection triggered by response code or by timeout; receive an Sx Session Request message from the CP, wherein the Sx Session Request message comprises a DL PDR associated with a first FAR, wherein the DL PDR indicates to the UP to retrieve a response code or to monitor if the Sx Session Request message has timed out; receive DL traffic matching the DL PDR from the first server (S 1 ); activate the second FAR when the matching DL traffic is received; redirect subsequent UL traffic to the S 2 . 
     ABBREVIATIONS 
     
         
         EPC Evolved Packet Core 
         CP Control Plane 
         UP User Plane 
         DL Downlink 
         UL Uplink 
         PDR Packet Detection Rule 
         FAR Forwarding Action Rule 
         LTE Long Term Evolution 
         MTC Machine Type Communication 
         UE User Equipment 
         PCRF Policy and Charging Rule Function 
         PGW Packet Data Network Gateway 
         SAE System Architecture Evolution 
         SGW Servicing Network Gateway