Patent Description:
Fifth Generation (<NUM>) mobile networks also support Ethernet traffic. The <NUM> network supports so-called Ethernet Protocol Data Unit (PDU) sessions, which can carry native Ethernet frames over the <NUM> mobile network. In case of Ethernet PDU sessions, the source Medium Access Control (MAC) address used at the terminal, or User Equipment (UE), side can be reported from the User Plane Function (UPF) to the Session Management Function (SMF). Whether or not to report the MAC address is controlled by the SMF. Note that there may be multiple MAC addresses used as source address, e.g., because there may be multiple Ethernet devices behind the UE that use the given PDU session. The UPF also reports the removal of the MAC address, i.e., when the MAC address has not been used over a given period of time. The reporting of the MAC address is defined in Third Generation Partnership Project (3GPP) Technical Specification (TS) <NUM> V15. <NUM> section <NUM>. Note that other information, such as Virtual Local Area Network (VLAN) tags, may also be reported in combination with the MAC addresses.

<FIG> illustrates reporting of MAC addresses as currently defined in 3GPP TS <NUM> V15. <NUM> section <NUM>. As illustrated, the 3GPP <NUM> System (5GS) includes a UE connected to a next generation Node B (gNB) that forms part of the <NUM> Radio Access Network (RAN). The gNB is connected to a <NUM> Core (5GC), which includes a UPF, an Access and Mobility Function (AMF), a SMF, a Policy and Charging Function (PCF), etc. The UPF is connected to an Ethernet network via a switch. This switch may be co-located with the UPF or separate from the UPF. The MAC address used at the UE side (by Ethernet Host A) is reported from the UPF to the SMF.

The MAC address reporting may be used by the SMF to further report to the PCF so that the PCF can install appropriate packet filters based on the MAC address information. The reporting may also be used by the SMF to install packet filters that map downlink traffic to the given PDU session, in case the UPF does not set up such packet filters autonomously. The MAC address reporting may also be used for other purposes such as to prepare for the possible relocation of the UPF, so that the MAC address information can be conveyed to the new target UPF.

Technical specification TS <NUM>, V15. <NUM>, describes that a DN-AAA server may provide the SMF with a list of allowed MAC addresses and/or a list of allowed VIDs for a particular PDU session. The SMF shall then set corresponding filtering rules in the UPF.

Document "Update Solution for IPTV support" by Huawei and HiSilicon, SA WG2 Meeting #127bis, <NUM> May - <NUM> June <NUM>, discloses that Multicast Support relies on the support of IGMP Join in UPF for binding the Multicast address included in the IGMP join message to the related PDU session from the <NUM>-RG.

The invention provides a method performed in a core network of a cellular communications system, a method performed in a User Plane Function, a User Plane Function and a network node for mapping a multicast MAC address to a PDU session, according to respective independent claims <NUM>, <NUM>, <NUM> and <NUM>.

Systems and methods are disclosed herein that relate to reporting a multicast Medium Access Control (MAC) address used by a particular Protocol Data Unit (PDU) session in a cellular communications system. According to the present disclosure, methods, network nodes, a UPF and an SMF according to the independent claims are provided. Developments are set forth in the dependent claims. In some embodiments, a method performed in a core network of a cellular communications system for mapping a multicast MAC address to a particular PDU session comprises, at a User Plane Function (UPF), obtaining multicast MAC address information comprising a multicast MAC address to be used on a particular PDU session and information that identifies either or both of a User Equipment (UE) associated with the particular PDU session and the particular PDU session. The method further comprises, at the UPF, reporting, to a Session Management Function (SMF) in the core network, use of the multicast MAC address on the particular PDU session. The method further comprises, at the SMF, receiving, from the UPF, the report of the use of the multicast MAC address on the particular PDU session, the report comprising the multicast MAC address to be used on the particular PDU session and using the multicast MAC address to perform one or more operational tasks. In this manner, it becomes possible to selectively use multicast MAC addresses on specific PDU sessions as destination addresses. This can enable the use of mechanisms such as Institute of Electrical and Electronics Engineers (IEEE) Time-Sensitive Networking (TSN) Frame Replication and Elimination for Reliability (FRER) for redundancy. The reporting of the MAC address may enable the setup of specific policy, Quality of Service (QoS), or charging filters so that the traffic flows are treated appropriately. The reporting of the multicast MAC address may also enable the potential relocation of the UPF, so that the SMF can provide the multicast MAC address information to the target UPF and the traffic flows can continue after mobility.

Embodiments of a method performed in a UPF and corresponding embodiments of a UPF or network node implementing a UPF are also disclosed. In some embodiments, a method performed in a User Plane Function, UPF, (<NUM>) for mapping a multicast MAC address to a particular PDU session in a core network of a cellular communications system comprise obtaining multicast MAC address information comprising a multicast MAC address to be used on a particular PDU session and information that identifies either or both of a UE associated with the particular PDU session and the particular PDU session. The method further comprises reporting, to a SMF in the core network, use of the multicast MAC address on the particular PDU session.

In some embodiments, reporting the use of the multicast MAC address on the particular PDU session comprises reporting, to the SMF, the multicast MAC address to be used on the particular PDU session. In some other embodiments, reporting the use of the multicast MAC address on the particular PDU session comprises reporting, to the SMF, the multicast MAC address to be used on the particular PDU session and either or both of the information that identifies the UE associated with the particular PDU session and the particular PDU session.

In some embodiments, the multicast MAC address information further comprises one or more Virtual Local Area Network (VLAN) tags.

In some embodiments, the information that identifies either or both of the UE associated with the particular PDU session and the particular PDU session comprises: (a) either or both of: (i) one or more unicast MAC addresses associated with the UE (<NUM>) and (ii) an identifier of the particular PDU session; (b) the identifier of the particular PDU session; (c) an identifier of the UE (<NUM>) associated with the particular PDU session; or (d) any combination of two or more of (a)-(c).

According to the invention, the UPF is coupled to an Ethernet network via a switch (<NUM>). In some embodiments, the switch is non-co-located with the UPF, and obtaining the multicast MAC address information comprises obtaining the multicast MAC address information from the switch. In some embodiments, obtaining the multicast MAC address information from the switch comprises receiving, from the switch, a control message comprising the multicast MAC address information. In some other embodiments, the switch is co-located with the UPF, and obtaining the multicast MAC address information comprises obtaining the multicast MAC address information from the switch.

In some embodiments, the method further comprises storing the multicast MAC address information.

In some embodiments, a UPF for mapping a multicast MAC address to a particular PDU session in a core network of a cellular communications system is adapted to obtain multicast MAC address information comprising a multicast MAC address to be used on a particular PDU session and information that identifies either or both of a UE associated with the particular PDU session and the particular PDU session. The UPF is further adapted to report, to a SMF in the core network, use of the multicast MAC address on the particular PDU session.

In some embodiments, a network node implementing a UPF for mapping a multicast MAC address to a particular PDU session in a core network of a cellular communications system comprises at least one network interface and processing circuitry associated with the at least one network interface. The processing circuity is configured to cause the network node to obtain multicast MAC address information comprising a multicast MAC address to be used on a particular PDU session and information that identifies either or both of a UE associated with the particular PDU session and the particular PDU session. The processing circuity is further configured to cause the network node to report, to a SMF in the core network, use of the multicast MAC address on the particular PDU session.

Embodiments of a method performed in a SMF and corresponding embodiments of an SMF and network node that implements an SMF are also disclosed. In some embodiments, a method performed in a SMF for mapping a multicast MAC address to a particular PDU session in a core network of a cellular communications system comprises receiving, from a UPF in the core network, information that reports use of a multicast MAC address on a particular PDU session. The information that reports use of the multicast MAC address on the particular PDU session comprises the multicast MAC address. The method further comprises using the information that reports use of the multicast MAC address on the particular PDU session to perform one or more operational tasks.

In some embodiments, the information that reports use of the multicast MAC address on the particular PDU session comprises the multicast MAC address to be used on the particular PDU session and information that identifies either or both of a UE associated with the particular PDU session and the particular PDU session. In some embodiments, the information that identifies either or both of the UE associated with the particular PDU session and the particular PDU session comprises: (a) either or both of: (i) one or more unicast MAC addresses associated with the UE and (ii) an identifier of the particular PDU session; (b) the identifier of the particular PDU session; (c) an identifier of the UE associated with the particular PDU session; or (d) any combination of two or more of (a)-(c).

In some embodiments, using the information that reports use of the multicast MAC address on the particular PDU session comprises providing one or more policy and charging filters to the UPF based on the information that reports use of the multicast MAC address on the particular PDU session. In some embodiments, the one or more policy and charging filters comprise one or more filters that map frames having the multicast MAC address to the particular PDU session.

In some embodiments, using the information that reports use of the multicast MAC address on the particular PDU session comprises storing the information that reports use of the multicast MAC address on the particular PDU session.

In some embodiments, using the information that reports use of the multicast MAC address on the particular PDU session comprises providing the information that reports use of the multicast MAC address on the particular PDU session to a new UPF in association with a UPF relocation procedure.

In some embodiments, the information that reports use of the multicast MAC address on the particular PDU session further comprises one or more VLAN tags.

In some embodiments, a SMF for mapping a multicast MAC address to a particular PDU session in a core network of a cellular communications system is adapted to receive, from a UPF in the core network, information that reports use of a multicast MAC address on a particular PDU session. The information that reports use of the multicast MAC address on the particular PDU session comprises the multicast MAC address. The SMF is further adapted to use the information that reports use of the multicast MAC address on the particular PDU session to perform one or more operational tasks.

In some embodiments, a network node implementing a SMF for mapping a multicast MAC address to a particular PDU session in a core network of a cellular communications system comprises at least one network interface and processing circuitry associated with the at least one network interface. The processing circuity is configured to cause the network node to receive, from a UPF in the core network, information that reports use of a multicast MAC address on a particular PDU session. The information that reports use of the multicast MAC address on the particular PDU session comprises the multicast MAC address. The processing circuity is further configured to cause the network node to use the information that reports use of the multicast MAC address on the particular PDU session to perform one or more operational tasks.

Radio Access Node: As used herein, a "radio access node" or "radio network node" is any node in a Radio Access Network (RAN) of a cellular communications network that operates to wirelessly transmit and/or receive signals.

Core Network Node: As used herein, a "core network node" is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Repository Function (NRF), a Policy and Charging Function (PCF), a Unified Data Management (UDM), or the like.

Some examples of a wireless device include, but are not limited to, a User Equipment (UE) in a 3GPP network and a Machine Type Communication (MTC) device.

Note that, in the description herein, reference may be made to the term "cell;" however, particularly with respect to <NUM> NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

There currently exist certain challenge(s). The current solution for Medium Access Control (MAC) address reporting in the <NUM> System (5GS) only reports unicast addresses that are used at the terminal side. Multicast or broadcast traffic may be forwarded towards the terminal, but its address is not specifically reported.

The current solution may cause problems in cases when there is an explicitly configured multicast MAC address to be used on a given Protocol Data Unit (PDU) session, so that we would like to avoid forwarding traffic with the given multicast MAC address to other PDU sessions. Currently, there is no way to bind a multicast MAC address to a specific PDU session, unless that multicast MAC address is explicitly configured into or signaled to the SMF or PCF. However, typically such an explicit configuration is not available at the SMF or PCF. Instead, the need for using a given multicast MAC address would arise in the Ethernet data network, which typically does not have any signaling interface to the SMF or PCF. The information on the multicast MAC address to be used would be typically available at the switch co-located with the UPF, or the switch used in combination with the UPF. There are situations, e.g., in case of using IEEE Time-Sensitive Networking (TSN) Frame Replication and Elimination for Reliability (FRER) (IEEE <NUM>. 1CB), when an explicitly configured multicast address is used. For example, for FRER, a central controller would use the same multicast MAC address on the two (or more) legs of the redundant data transmission. That multicast MAC address would be used only as a destination address for the data traffic towards the UE, but not used by the UE as the source address. The traffic with the given multicast address is intended to the UE only, and should not be forwarded to other UEs. Another example is optimizing the flooding of multicast traffic. Flooding only to where we have receivers is an existing optimization issue in Ethernet networks. Explicitly configured multicast addresses help reduce unnecessary flooding.

With the current 3GPP solution, there is no good way to map such traffic to a given multicast MAC address to specific PDU sessions. Also, if multicast MAC addresses are not reported, they would also not be available at the SMF to be used for UPF relocation. In case of UPF relocation, the SMF provides the relevant Ethernet context to the new target UPF, including MAC addresses used over the given PDU session.

Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges. In some embodiments, when the UPF becomes aware of an explicitly configured multicast MAC address to be used on a given PDU session, that MAC address is also reported to the SMF similarly as unicast MAC addresses. The UPF may become aware of such explicitly configured multicast MAC addresses based on information that it receives from its associated Ethernet switch. That associated switch may either be co-located with the UPF or non-co-located with the UPF, where the UPF and switch have an explicit signaling relationship.

In some embodiments, when the use of a multicast MAC address is explicitly configured into a switch that is associated with a 3GPP UPF, the UPF reports the use of the given multicast MAC address to the SMF.

Certain embodiments may provide one or more of the following technical advantage(s). When using embodiments of the present disclosure, it becomes possible to selectively use multicast MAC addresses on specific PDU sessions as destination addresses. This can enable the use of mechanisms such as IEEE TSN FRER for redundancy. The reporting of the MAC address enables the setup of specific policy, Quality of Service (QoS), or charging filters so that the traffic flows are treated appropriately. The reporting of the multicast MAC address also enables the potential relocation of the UPF, so that the SMF can provide the multicast MAC address information to the target UPF and the traffic flows can continue after mobility.

Systems and methods are disclosed herein that are implemented in a cellular communications network such as, e.g., a 3GPP <NUM> network. Note, however, that the present disclosure is not limited to 3GPP <NUM> networks. Rather, the embodiments disclosed herein are equally applicable to other types of cellular communications networks. In this regard, <FIG> illustrates one example of a cellular communications network <NUM> in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications network <NUM> is a <NUM> NR network. In this example, the cellular communications network <NUM> includes base stations <NUM>-<NUM> and <NUM>-<NUM>, which in <NUM> NR are referred to as gNBs, controlling corresponding macro cells <NUM>-<NUM> and <NUM>-<NUM>. The base stations <NUM>-<NUM> and <NUM>-<NUM> are generally referred to herein collectively as base stations <NUM> and individually as base station <NUM>. Likewise, the macro cells <NUM>-<NUM> and <NUM>-<NUM> are generally referred to herein collectively as macro cells <NUM> and individually as macro cell <NUM>. The cellular communications network <NUM> may also include a number of low power nodes <NUM>-<NUM> through <NUM>-<NUM> controlling corresponding small cells <NUM>-<NUM> through <NUM>-<NUM>. The low power nodes <NUM>-<NUM> through <NUM>-<NUM> can be small base stations (such as pico or femto base stations) or Remote Radio Heads (RRHs), or the like. Notably, while not illustrated, one or more of the small cells <NUM>-<NUM> through <NUM>-<NUM> may alternatively be provided by the base stations <NUM>. The low power nodes <NUM>-<NUM> through <NUM>-<NUM> are generally referred to herein collectively as low power nodes <NUM> and individually as low power node <NUM>. Likewise, the small cells <NUM>-<NUM> through <NUM>-<NUM> are generally referred to herein collectively as small cells <NUM> and individually as small cell <NUM>. The base stations <NUM> (and optionally the low power nodes <NUM>) are connected to a core network <NUM>, which for <NUM> is the <NUM> Core (5GC).

Note that while the example of <FIG> illustrates cellular access to the core network <NUM> (e.g., 3GPP access to the 5GC), the present disclosure is also applicable to non-cellular access to the core network <NUM> (e.g., non-3GPP access to the 5GC).

<FIG> illustrates a wireless communication system represented as a <NUM> network architecture composed of core Network Functions (NFs), where interaction between any two NFs is represented by a point-to-point reference point/interface. <FIG> can be viewed as one particular implementation of the system <NUM> of <FIG>.

Seen from the access side the <NUM> network architecture shown in <FIG> comprises a plurality of UEs <NUM> connected to either a RAN or an Access Network (AN) as well as an AMF <NUM>. Typically, the R(AN) comprises base stations <NUM>, e.g. such as eNBs or gNBs or similar. Seen from the core network side, the 5GC NFs shown in <FIG> include an NSSF <NUM>, an AUSF <NUM>, a UDM <NUM>, the AMF <NUM>, a SMF <NUM>, a PCF <NUM>, an Application Function (AF) <NUM>, and a UPF <NUM>.

Reference point representations of the <NUM> network architecture are used to develop detailed call flows in the normative standardization. The N1 reference point is defined to carry signaling between the UE <NUM> and the AMF <NUM>. The reference points for connecting between the AN and the AMF <NUM> and between the AN and the UPF <NUM> are defined as N2 and N3, respectively. There is a reference point, N11, between the AMF <NUM> and the SMF <NUM>. N4 is used by the SMF <NUM> and the UPF <NUM> so that the UPF <NUM> can be set using the control signal generated by the SMF <NUM>, and the UPF <NUM> can report its state to the SMF <NUM>. N9 is the reference point for the connection between different UPFs <NUM>, and N14 is the reference point connecting between different AMFs <NUM>, respectively. N15 and N7 are defined since the PCF <NUM> applies policy to the AMF <NUM> and the SMF <NUM>, respectively. N12 is required for the AMF <NUM> to perform authentication of the UE <NUM>. N8 and N10 are defined because the subscription data of the UE is required for the AMF <NUM> and the SMF <NUM>.

The 5GC network aims at separating user plane and control plane. The user plane carries user traffic while the control plane carries signaling in the network. In <FIG>, the UPF <NUM> is in the user plane and all other NFs, i.e., the AMF <NUM>, SMF <NUM>, PCF <NUM>, AF <NUM>, NSSF <NUM>, AUSF <NUM>, and UDM <NUM>, are in the control plane. Separating the user and control planes guarantees each plane resource to be scaled independently. It also allows UPFs <NUM> to be deployed separately from control plane functions in a distributed fashion. In this architecture, UPFs <NUM> may be deployed very close to UEs <NUM> to shorten the Round Trip Time (RTT) between UEs <NUM> and data network for some applications requiring low latency.

The core <NUM> network architecture is composed of modularized functions. For example, the AMF <NUM> and SMF <NUM> are independent functions in the control plane. Separated AMF <NUM> and SMF <NUM> allow independent evolution and scaling. Other control plane functions like the PCF <NUM> and AUSF <NUM> can be separated as shown in <FIG>. Modularized function design enables the 5GC network to support various services flexibly.

The user plane supports interactions such as forwarding operations between different UPFs <NUM>.

<FIG> illustrates a <NUM> network architecture using service-based interfaces between the NFs in the control plane, instead of the point-to-point reference points/interfaces used in the <NUM> network architecture of <FIG>. However, the NFs described above with reference to <FIG> correspond to the NFs shown in <FIG>. The service(s) etc. that a NF provides to other authorized NFs can be exposed to the authorized NFs through the service-based interface. In <FIG> the service based interfaces are indicated by the letter "N" followed by the name of the NF, e.g. Namf for the service based interface of the AMF <NUM> and Nsmf for the service based interface of the SMF <NUM>, etc. The NEF <NUM> and the NRF <NUM> in <FIG> are not shown in <FIG> discussed above. However, it should be clarified that all NFs depicted in <FIG> can interact with the NEF and the NRF of <FIG> as necessary, though not explicitly indicated in <FIG>.

Some properties of the NFs shown in <FIG> and <FIG> may be described in the following manner. The AMF <NUM> provides UE-based authentication, authorization, mobility management, etc. A UE <NUM> even using multiple access technologies is basically connected to a single AMF <NUM> because the AMF <NUM> is independent of the access technologies. The SMF <NUM> is responsible for session management and allocates Internet Protocol (IP) addresses to UEs <NUM>. It also selects and controls the UPF <NUM> for data transfer. If a UE <NUM> has multiple sessions, different SMFs <NUM> may be allocated to each session to manage them individually and possibly provide different functionalities per session. The AF <NUM> provides information on the packet flow to the PCF <NUM> responsible for policy control in order to support QoS. Based on the information, the PCF <NUM> determines policies about mobility and session management to make the AMF <NUM> and SMF <NUM> operate properly. The AUSF 304supports authentication function for UEs <NUM> or similar and thus stores data for authentication of UEs <NUM> or similar while the UDM <NUM> stores subscription data of the UE <NUM>. The Data Network (DN), which is not part of the 5GC network, provides Internet access or operator services and similar.

Now the present disclosure turns to a more detailed description of some embodiments of the present disclosure. In some embodiments, when the UPF <NUM> becomes aware of an explicitly configured multicast MAC address to be used on a given PDU session, that MAC address is also reported to the SMF <NUM> similarly as unicast MAC addresses. The UPF <NUM> may become aware of such explicitly configured multicast MAC addresses based on information that it receives from its associated Ethernet switch. That associated switch may either be co-located with the UPF <NUM> or non-co-located with the UPF, where the UPF <NUM> and switch have an explicit signaling relationship.

<FIG> illustrates multicast MAC address reporting in accordance with some embodiments of the present disclosure. The illustrated 3GPP network is one example of the cellular communications network <NUM>. As illustrated, the solution consists of the following steps. Note that while the following functions are referred to as "steps," these "steps" may be performed in any desired order (or even simultaneously) unless otherwise required.

Step <NUM>: A multicast MAC address is configured to be used at a switch <NUM> in the Ethernet network, where the switch <NUM> is associated with a UPF <NUM> in the 3GPP network. The configuration may be performed, e.g., by a central controller <NUM> (such as, e.g., a Central Network Controller (CNC) of an IEEE TSN), or by the use of a configuration protocol, or other methods (e.g., Internet Group Management Protocol (IGMP) snooping). This multicast MAC address applies to a particular PDU session (or two or more particular PDU sessions) in the 3GPP network.

Step <NUM>: The switch <NUM> is associated with the UPF <NUM> and provides multicast MAC address information to the UPF <NUM>. In some embodiments, the UPF <NUM> is co-located with the switch <NUM>, and the provision of the multicast MAC address takes place internally within the node in which the UPF <NUM> and the switch <NUM> are co-located, in which case the multicast MAC address information is, e.g., sent from the switch <NUM> to the co-located UPF <NUM>. In some other embodiments, the UPF <NUM> and the switch <NUM> are separate nodes (i.e., non-co-located), and an explicit control message is sent from the switch <NUM> to the UPF <NUM>, where this control message includes the multicast MAC address information. In either case, the multicast MAC address information provided by the switch <NUM> to the UPF <NUM> includes:.

Note that, in step <NUM>, the switch <NUM> may provide, to the UPF <NUM>, separate multicast MAC address information for multiple PDU sessions or multiple UEs simultaneously (e.g., in the same control message).

Step <NUM>: The UPF <NUM> reports the use of the given multicast MAC address on the given PDU session to the SMF <NUM>. In some embodiments, this reporting is done in a manner that is similar to the manner in which the UPF <NUM> reports the use of a MAC address on a PDU session (e.g., as described in 3GPP Technical Specification (TS) <NUM> V15. <NUM> section <NUM>. For instance, the UPF <NUM> may report (e.g., send) the multicast MAC address for the particular PDU session to the SMF <NUM> (e.g., by sending a message comprising the respective multicast MAC address information, or relevant portion thereof, to the SMF <NUM>). The UPF <NUM> may also report one or more VLAN tags in combination with the multicast MAC address when applicable.

Step <NUM> (optional): The UPF <NUM> may optionally store the multicast MAC address information on its own.

Step <NUM>: In response to the multicast MAC address reporting, the SMF <NUM> uses the reported multicast MAC address (and optionally any associated information such as, e.g., VLAN tags) to perform one or more actions. More specifically, the SMF <NUM> may:.

In case the multicast MAC address is released and no longer used, a procedure similar to that discussed above can be used to report this change to the SMF <NUM>.

In the description above, the multicast MAC address is used for a single PDU session; however, the present disclosure is not limited thereto. The multicast MAC address may be applied to any number of one or more particular PDU sessions where the reported multicast MAC address information includes both the multicast MAC address and information that indicates the one or more particular PDU session to which the multicast MAC address applies.

As a result of the explicit configuration of the multicast MAC address, frames with the given multicast MAC address as the destination are only forwarded to the particular PDU session(s) for which they have explicitly been configured, and not to other PDU sessions. Of course, the switch may forward multicast frames on other fixed interfaces as today.

Note that there may also be multicast MAC addresses used in the system which are not explicitly configured or learned by a signaling protocol (e.g., via snooping). Such multicast frames may be delivered on multiple or all PDU sessions, depending on configuration. The use of such multicast MAC addresses might not be explicitly reported to the SMF <NUM>. Local configuration may be used to select which types of multicast MAC addresses are reported (e.g., depending on how the multicast MAC address was configured/learned).

As an optional extension, it may be possible to also report, in combination with the multicast MAC address, information on how the multicast MAC address was configured (e.g., whether it was configured by the central controller <NUM> (whose identity might also be given), whether it was set by IGMP snooping, etc.). This information may help the SMF <NUM> and/or the PCF <NUM> to determine the most appropriate set of policy and charging information to be provided for the traffic.

<FIG> is a schematic block diagram of a network node <NUM> according to some embodiments of the present disclosure. The network node <NUM> may be, for example, a core network node (e.g., a node implementing the UPF <NUM> or SMF <NUM> of <FIG>). As illustrated, the network node <NUM> includes one or more processors <NUM> (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory <NUM>, and a network interface <NUM>. The one or more processors <NUM> are also referred to herein as processing circuitry. The one or more processors <NUM> operate to provide one or more functions of a network node <NUM> as described herein (e.g., with respect to <FIG>). In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory <NUM> and executed by the one or more processors <NUM>.

<FIG> is a schematic block diagram that illustrates a virtualized embodiment of the network node <NUM> according to some embodiments of the present disclosure.

As used herein, a "virtualized" network node is an implementation of the network node <NUM> in which at least a portion of the functionality of the network node <NUM> is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the network node <NUM> includes one or more processing nodes <NUM> coupled to or included as part of a network(s) <NUM>. Each processing node <NUM> includes one or more processors <NUM> (e.g., CPUs, ASICs, FPGAs, and/or the like), memory <NUM>, and a network interface <NUM>. In this example, functions <NUM> of the network node <NUM> described herein (e.g., with respect to <FIG>) are implemented at the one or more processing nodes <NUM> or distributed across the two or more processing nodes <NUM> in any desired manner. In some particular embodiments, some or all of the functions <NUM> of the network node <NUM> described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) <NUM>.

In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of network node <NUM> or a node (e.g., a processing node <NUM>) implementing one or more of the functions <NUM> of network node <NUM> in a virtual environment according to any of the embodiments described herein is provided.

<FIG> is a schematic block diagram of the network node <NUM> according to some other embodiments of the present disclosure. The module(s) <NUM> provide the functionality of the network node <NUM> described herein (e.g., the functions of the UPF <NUM> or the functions of the SMF <NUM> described above with respect to, e.g., <FIG>). This discussion is equally applicable to the processing node <NUM> of <FIG> where the modules <NUM> may be implemented at one of the processing nodes <NUM> or distributed across multiple processing nodes <NUM>.

Claim 1:
A method performed in a core network of a cellular communications system for mapping a multicast Medium Access Control, MAC, address to a particular Protocol Data Unit, PDU, session, comprising:
• at a User Plane Function, UPF, (<NUM>):
∘ obtaining (Fig. <NUM>, step <NUM>) multicast MAC address information comprising:
▪ a multicast MAC address to be used on a particular PDU session; and
▪ information that identifies a User Equipment, UE, (<NUM>) associated with the particular PDU session, wherein the UPF (<NUM>) is coupled to an Ethernet network via a switch (<NUM>), and wherein the switch (<NUM>) is non-co-located with the UPF (<NUM>) and obtaining (Fig. <NUM>, step <NUM>) the multicast MAC address information comprises obtaining (Fig. <NUM>, step <NUM>) the multicast MAC address information from the switch (<NUM>) by receiving (Fig. <NUM>, step <NUM>) a control message comprising the multicast MAC address information, or wherein the switch (<NUM>) is co-located with the UPF (<NUM>) and obtaining (Fig. <NUM>, step <NUM>) the multicast MAC address information comprises obtaining (Fig. <NUM>, step <NUM>) the multicast MAC address information from the switch (<NUM>); and
∘ reporting (Fig. <NUM>, step <NUM>), to a Session Management Function, SMF, (<NUM>) in the core network, use of the multicast MAC address on the particular PDU session; and
• at the SMF (<NUM>):
∘ receiving (Fig. <NUM>, step <NUM>), from the UPF (<NUM>), the report of the use of the multicast MAC address on the particular PDU session, the report comprising the multicast MAC address to be used on the particular PDU session; and
using (Fig. <NUM>, step <NUM>) the multicast MAC address to perform one or more operational tasks.