Methods, systems, and computer-readable media for distributing S1 connections to a mobility management entity (MME) and distributing N2 connections to an access and mobility management function (AMF)

Abstract

A method for distributing connections to mobility management node instances includes publishing IP addresses for receiving connection requests and ingress messages from RAN nodes. The method also includes maintaining connection load measurements of the mobility management node instances, receiving a connection request message generated by a RAN node to initiate a connection with one of the mobility management node instances, applying a connection distribution algorithm to select a mobility management node instance to handle the connection request message, and creating an association between the IP address of the selected mobility management node instance and the IP address and port of the RAN node extracted from a source IP address and source port field of the connection request. The method also includes forwarding the connection request message to the selected mobility management node instance.

Description

[0001] Priority Statement

[0002] This application claims priority to U.S. Patent Application Serial No. 17 / 027,633, filed on September 21, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This document describes topics relating to connection distribution in mobile communication networks. More specifically, it describes methods, systems, and computer-readable media for distributing S1 connections to an MME and N2 connections to an AMF. Background Technology

[0004] In 4G mobile communication networks, the Mobility Management Entity (AMF) is a node that communicates with the Radio Access Node (MME) to perform mobility-related functions on behalf of mobile subscribers. In 5G communication networks, the AMF is the node that communicates with the Radio Access Node (MME) to perform mobility-related functions on behalf of users. The connection between the Radio Access Node and the MME is called an S1 connection because the interface between them is an S1 interface. Similarly, in 5G communication networks, the interface between the Radio Access Node and the AMF is called an N2 interface, and connections on this interface are called N2 connections.

[0005] One issue in mobile communication networks is that MME and AMF nodes may need to be scaled up or down, especially in cloud configurations. During the scaling up or down of MME or AMF nodes, it may be necessary to add or remove S1 or N2 connections. Adding or removing S1 or N2 connections can disrupt radio access nodes.

[0006] Given these difficulties, there is a need for improved methods, systems, and computer-readable media to allow reconfiguration of MME or AMF nodes without adversely affecting S1 or N2 connections to radio access nodes. Summary of the Invention

[0007] A method for distributing connections to a mobility management node instance includes publishing an Internet Protocol (IP) address for receiving connection requests (such as S1 or N2 connection requests) and ingress messages from radio access network (RAN) nodes. The method also includes maintaining connection load measurements of the mobility management node instance by a connection load balancer. The method further includes receiving, at the connection load balancer, a connection request message generated by the RAN node for initiating a connection with one of the mobility management node instances. The method also includes the connection load balancer applying a connection distribution algorithm to select a mobility management node instance to handle the connection request message. The method further includes the connection load balancer creating an association between the IP address of the selected mobility management node instance and the IP address and port of the RAN node extracted from the source IP address field and source port field of the connection request message, in a database or cache at least partially populated by the connection load balancer for protocol continuity. The method also includes the connection load balancer forwarding the connection request message to the mobility management node instance selected using the connection distribution algorithm.

[0008] According to another aspect of the subject described in this article, the publication of IP addresses includes the connection load balancer broadcasting gratuitous ARP or Internet Control Management Protocol version 6 (ICMPv6) neighbor discovery messages that associate the IP address with the connection load balancer's Media Access Control (MAC) address.

[0009] According to another aspect of the subject described in this article, the IP address published by the connection load balancer can be associated with the loopback interface of the mobility management node instance. Associating the IP address with the loopback address of the mobility management node instance allows the mobility management node instance to use the IP address as an alias without broadcasting a Broadcast Address Resolution Protocol (ARP) or ICMP message containing the IP address.

[0010] According to another aspect of the subject matter described herein, determining whether a message is an initial message or a subsequent message may include determining that the message is an initial message and determining whether a connection has already been assigned to one of the mobility management node instances may include determining that the connection has not yet been assigned to one of the mobility management node instances. If the message is determined to be an initial message and the connection has not yet been assigned to one of the mobility management node instances, then the S1 connection is assigned to one of the mobility management node instances using a load balancing algorithm. The initial message is then forwarded to the mobility management node instance assigned to the S1 connection.

[0011] According to another aspect of the subject matter described herein, determining whether a message is an initial message or a subsequent message associated with an S1 connection may include determining that the message is a subsequent message. Determining whether an S1 connection associated with a subsequent message has been assigned to one of the message processors may include determining that the S1 connection has been assigned to one of the mobility management node instances. If the message is determined to be a subsequent message to which an S1 connection has been assigned to one of the mobility management node instances, then the message may be forwarded to the assigned mobility management node instance.

[0012] According to another aspect of the subject matter described herein, determining whether a message is an initial message or a subsequent message may include determining that the message is an initial message and determining whether a connection has already been assigned to one of the mobility management node instances may include determining that the connection has not yet been assigned to one of the mobility management node instances. If the message is determined to be an initial message and the connection has not yet been assigned to one of the mobility management node instances, then the N2 connection is assigned to one of the mobility management node instances using a load balancing algorithm. The initial message is then forwarded to the mobility management node instance assigned to the N2 connection.

[0013] According to another aspect of the subject matter described herein, determining whether a message is an initial message or a subsequent message associated with an N2 connection may include determining that the message is a subsequent message. Determining whether the N2 connection associated with the subsequent message has been assigned to one of the message processors may include determining that the N2 connection has been assigned to one of the mobility management node instances. If the message is determined to be a subsequent message to which an N2 connection has been assigned to one of the mobility management node instances, then the message may be forwarded to the assigned mobility management node instance.

[0014] According to another aspect of the subject matter described herein, a method for distributing connections to a mobility management node instance includes, at the mobility management node instance, listening for an IP address published by a connection load balancer.

[0015] According to another aspect of the subject matter described herein, a group refers to a connection group initiated from a specific peer RAN node to the mobility management node. Therefore, connections from each peer RAN node are isolated into different groups at the connection load balancer. Each group is identified by one or more IP addresses of the peer RAN node at the connection load balancer, which are used as the source address of one or more initiating messages.

[0016] According to another aspect of the subject described in this article, for each S1 connection request that logs onto the connection load balancer, its source IP address(s) is used to identify the group evaluating the load balancing algorithm.

[0017] According to another aspect of the subject matter described herein, assigning one of the mobility management node instances to an S1 connection using a load balancing algorithm involves maintaining a group count for each mobility management node instance for each group, where the group count indicates the number of S1 connections assigned to each mobility management node instance. For each mobility management node instance, the group count difference between the mobility management node instance's group count and its lowest group count is calculated. Message processors with a group count difference less than a connection distribution threshold are included as connection distribution candidates. Mobility management node instances with a group count difference greater than or equal to the connection distribution threshold are excluded from consideration as connection distribution candidates.

[0018] According to another aspect of the subject described in this article, for each N2 connection request that logs onto the connection load balancer, its source IP address(s) is used to identify the group evaluating the load balancing algorithm.

[0019] According to another aspect of the subject matter described herein, assigning one of the mobility management node instances to an N2 connection using a load balancing algorithm involves maintaining a group count for each mobility management node instance for each group, where the group count indicates the number of N2 connections assigned to each mobility management node instance. For each mobility management node instance, the group count difference between the mobility management node instance's group count and its lowest group count is calculated. Mobility management node instances with a group count difference less than a connection distribution threshold are included as connection distribution candidates. Message processors with a group count difference greater than or equal to the connection distribution threshold are excluded from consideration as connection distribution candidates.

[0020] According to another aspect of the subject matter described herein, a method for distributing connections to mobility management node instances includes detecting a failure in one of the mobility management node instances and automatically routing connection request messages to available mobility management node instances.

[0021] According to another aspect of the subject matter described herein, a method for distributing connections to mobility management node instances includes detecting the reconstruction of mobility management node instances, and applying a connection distribution algorithm includes including the reconstructed mobility management node instances as candidates for selection in the connection distribution algorithm.

[0022] According to another aspect of the subject matter described herein, a method for distributing connections to mobility management node instances includes detecting the availability of new mobility management node instances and applying a connection distribution algorithm, including including the new mobility management node instances as candidates for selection in the connection distribution algorithm.

[0023] According to another aspect of the subject matter described herein, a system for distributing connections to mobility management node instances is provided. The system includes a connection load balancer comprising at least one processor and memory. The system also includes an S1 / N2 connection distributor for publishing Internet Protocol (IP) addresses for receiving connection requests and ingress messages from radio access network (RAN) nodes, maintaining connection load measurements of the mobility management node instances, receiving connection request messages generated by RAN nodes for initiating connections with one of the mobility management node instances, applying a connection distribution algorithm to select a mobility management node instance to handle the connection request message, creating an association between the IP address of the selected mobility management node instance and the IP address and port of the RAN node extracted from the source IP address field and source port field of the connection request message, in a database or cache at least partially populated by the connection load balancer for protocol continuity, and forwarding the connection request message to the mobility management node instance selected using the connection distribution algorithm.

[0024] According to another aspect of the subject matter described in this article, the S1 / N2 connection distributor is configured to advertise IP addresses by broadcasting gratuitous Address Resolution Protocol (ARP) or ICMPv6 neighbor discovery messages to border gateway nodes, which associate the IP address of the connection load balancer interface with the Media Access Control (MAC) address.

[0025] According to another aspect of the subject matter described herein, the S1 / N2 connection distributor is configured to maintain one or more groups. Each group is configured with one or more IP addresses of the peer RAN represented by that group.

[0026] According to another aspect of the subject matter described in this article, the S1 / N2 connection distributor is configured with a connection distribution threshold.

[0027] According to another aspect of the subject matter described herein, the S1 / N2 connection distributor is configured to maintain connection loading information for each configured group. For each configured group, the S1 / N2 connection distributor maintains a group count for each mobility management node instance, wherein the group count includes a count of the number of connections with the mobility management node instance, and wherein the S1 / N2 connection distributor is also configured to calculate the group count difference between the group count of the mobility management node instance and the lowest group count of the mobility management node instance for each mobility management node instance, and to include mobility management node instances with a group count difference less than a connection distribution threshold as connection distribution candidates.

[0028] According to another aspect of the subject described in this article, the S1 / N2 connection dispatcher is configured to detect a failure in one of the mobility management node instances and automatically route connection request messages to an available mobility management node instance.

[0029] According to another aspect of the subject matter described herein, the S1 / N2 connection dispatcher is configured to detect the reconstruction of mobility management node instances and include the reconstructed mobility management node instances as candidates for connection dispatching algorithms.

[0030] According to another aspect of the subject matter described in this paper, the S1 / N2 connection distributor is configured to detect the availability of new mobility management node instances and include new mobility management node instances as candidates for the connection distribution algorithm.

[0031] According to another aspect of the subject matter described herein, a non-transitory computer-readable medium is provided having executable instructions stored thereon, which, when executed by a computer's processor, control the computer to perform steps. These steps include: a connection load balancer publishing Internet Protocol (IP) addresses for receiving connection requests and ingress messages from Radio Access Network (RAN) nodes; the connection load balancer maintaining connection load measurements of Mobility Management Node (MMR) instances; receiving at the connection load balancer a connection request message generated by a RAN node for initiating a connection with one of the MMR instances; applying a connection distribution algorithm by the connection load balancer to select a MMR instance to handle the connection request message; creating an association between the IP address of the selected MMR instance and the IP address and port of the RAN node extracted from the source IP address and source port fields of the connection request message, for protocol continuity, and in a database or cache at least partially populated by the connection load balancer; and forwarding the connection request message to the MMR instance by the connection load balancer.

[0032] According to another aspect of the subject matter described herein, connection request messages include connection request messages for S1 or N2 connections.

[0033] The subject matter described herein can be implemented in hardware, software, firmware, or any combination thereof. Therefore, as used herein, the terms “function,” “node,” or “module” refer to hardware, which may also include software and / or firmware components for implementing the described features. In one exemplary embodiment, the subject matter described herein can be implemented using a computer-readable medium having computer-executable instructions stored thereon, which control computer execution steps when executed by a computer’s processor. Exemplary computer-readable media suitable for implementing the subject matter described herein include non-transitory computer-readable media, such as disk storage devices, on-chip memory devices, programmable logic devices, and application-specific integrated circuits (ASICs). Furthermore, computer-readable media implementing the subject matter described herein may reside on a single device or computing platform, or may be distributed across multiple devices or computing platforms. Attached Figure Description

[0034] The subject matter described in this article will now be explained with reference to the accompanying diagram:

[0035] Figure 1 This is a network diagram illustrating the S1 or N2 connection between a radio access node and an MME or AMF instance;

[0036] Figure 2 This is a network diagram of the problems that occur when an MME or AMF node instance crashes;

[0037] Figure 3 This is a network diagram illustrating a mobile communication network with a connection load balancer used to load balance S1 / N2 connections to MME / AMF instances, which avoids at least some of the difficulties associated with the current system.

[0038] Figure 4 This is a network diagram illustrating the use of a connection load balancer to load balance the inbound traffic on connection S1 or N2.

[0039] Figure 5 This is a network diagram illustrating outbound traffic flow in a mobile communication network that includes a load balancer.

[0040] Figure 6A and 6B This is a flowchart illustrating the call process for initializing the load balancer connection.

[0041] Figure 7 This is a flowchart illustrating the call flow of connection distribution using a connection load balancer;

[0042] Figure 8 This is a flowchart illustrating the call flow for using the protocol continuity of a connection load balancer;

[0043] Figure 9This is a network diagram illustrating the establishment of RAN connections using a connected load balancer;

[0044] Figure 10 This is a block diagram illustrating an exemplary connection of a load balancer; and

[0045] Figure 11 This is a flowchart illustrating an exemplary process performed by a connection load balancer for S1 / N2 connection distribution. Detailed Implementation

[0046] Mobile networks have evolved alongside various technologies and interconnectivity to carry signaling. One current challenge for mobile communication networks is the migration of applications and nodes providing services within the network to the cloud. Cloud-based environments also require intelligent scaling up and down of the network. MME / AMF nodes may need to be reconfigured if they scale up / down in the cloud. During scaling up / down, all S1 / N2 connections need to be added / removed. An S1 connection is the connection between the Radio Access Network (RAN) node and the MME. An N2 connection is the connection between the RAN node and the AMF.

[0047] This article describes a solution to the problem of reconfiguring MME / AMF nodes using a Connected Load Balancer (CLB) that may be located in the cloud. This will allow the network to manage the scaling up and down of the MME and / or AMF without affecting RAN nodes connected to the MME / AMF nodes in the cloud or on-premises.

[0048] In the current system, multiple MME / AMF nodes operate as multiple instances to simplify the scaling / high availability handling of S1 / N2 traffic from the RAN side, ensuring that each MME / AMF instance has a dedicated connection to the external RAN node. Each MME / AMF instance can have multiple S1 / N2 connections from the same RAN node. A RAN node can have S1 / N2 connections across multiple MME / AMF instances to achieve high availability.

[0049] When any one or more MME / AMF instances fail (due to errors or scaling down), all S1 / N2 connections to those instances are lost. When the MME / AMF instances come online (after disaster recovery or expansion), new S1 / N2 connections must be configured from the RAN. Because of this, remote RAN nodes seeking to reconnect to MME / AMF instances need to manage each S1 / N2 connection with a different IP address to achieve load distribution across MME / AMF instances. Requiring the remote RAN to manage each S1 / N2 connection with a different IP address individually creates a configuration burden on the remote RAN nodes, especially when reconnections need to be re-established after the MME or AMF becomes operational again after a period of inactivity.

[0050] Figure 1 The diagram illustrates RAN nodes connected to multiple MME / AMF instances, where an MME / AMF instance represents a single MME / AMF node. (Reference) Figure 1 RAN node 100 is connected to multiple MME / AMF instances 102 via S1 / N2 connection 104. Each MME / AMF instance 102 includes Ethernet interfaces 106 on networks A and B. Each Ethernet interface 106 includes a MAC address, and a separate IP address is associated with each Ethernet interface 106.

[0051] In the example shown, each of the S1 / N2 connections 104 includes a primary ingress connection path 108 associated with one of the Ethernet interfaces of the MME / AMF 102 and a secondary ingress connection path 110 associated with another Ethernet interface 106 of the MME / AMF instance 102. The primary and secondary communication paths can be multihomed connection paths based on the Flow Control Transmission Protocol (SCTP). However, the subject matter described herein is not limited to using SCTP multihomed connections with only two associations. The number of associations can extend from 1 to the maximum number of associations supported by the SCTP protocol. However, the subject matter described herein is not limited to using SCTP as the transport layer protocol. Transmission Control Protocol (TCP) can be used instead of SCTP without departing from the scope of the subject matter described herein.

[0052] In the examples shown, IP address IP-Node-NA is the IP address of MME / AMF instance-1 102 on the signaling device or Ethernet interface A 106. IP address IP-Node-NB is the IP address of MME / AMF instance-1 102 on signaling device B or Ethernet interface B 106. IP address IP-Node-NA is the IP address of MME / AMF instance-N 102 on the signaling device or Ethernet interface A 106. IP address IP-Node-NB is the IP address of MME / AMF instance-N 102 on the signaling device or Ethernet interface B 106.

[0053] Remote RAN nodes can connect to MME / AMF instances via S1 / N2 connections, where the MME / AMF instance is implemented on a single processor or multiple processors, depending on the chosen redundancy model. The topics described herein are not limited to managing S1 / N2 connections to MME / AMF instances implemented on a single process or multiple processors. Either scenario is intended to fall within the scope of the topics discussed herein.

[0054] Figure 2The diagram illustrates some issues with the current network architecture when an MME / AMF instance fails. When an MME / AMF instance fails, RAN nodes previously connected to the affected MME / AMF may need to reconfigure the affected connections using the recovered IP address of another MME / AMF instance. This reconfiguration is a burden on both ends of the S1 / N2 connection.

[0055] Besides reconfiguration issues caused by the current system architecture, connections may not be automatically distributed to the least loaded MME / AMF instances. RAN nodes may not be able to see the loading status of MME / AMF instances, especially when instances change due to outages or cloud configuration changes. Therefore, the RAN nodes' distribution of S1 / N2 connections may be suboptimal.

[0056] Another potential issue with the current network architecture is that when any MME / AMF instance (or multiple instances) fails, connections to it / them are not automatically redistributed to other MME / AMF instances, leaving fewer operational connections unless manual intervention is performed to reconfigure connections to other MME / AMF instances. Furthermore, automatic connection reconfiguration may not be possible when an MME / AMF instance stops service.

[0057] exist Figure 2 In the example shown, when one of the MME / AMF instances 102 fails, the S1 / N2 connection to the failed or out-of-service MME / AMF instance 102 is lost. Reconnection attempts to the failed MME / AMF 102 will fail. Furthermore, there is no automatic load balancing to the remaining MME / AMF 102.

[0058] To avoid or at least mitigate some of the difficulties associated with the current S1 / N2 connectivity architecture, a connectivity load balancer can be provided between one or more RAN nodes and MME / AMF instances to perform automatic reconfiguration of connectivity when the MME / AMF instance configuration changes, without requiring reconfiguration of the connectivity load balancer and the remote RAN nodes. For example, the connectivity load balancer can be used to address… Figure 2 The issues mentioned in the text.

[0059] In one implementation, the connection load balancer exposes a single set of public IP addresses to connect to all MME / AMF instances used to provide services to RAN nodes. This provides MME / AMF nodes with the flexibility to scale up or down without changing the public IP address information provided to RAN nodes. Because the public IP addresses exposed by the connection load balancer are independent of the MME / AMF configuration, the MME / AMF configuration can be changed without requiring remote RAN nodes to reconfigure the S1 / N2 connection.

[0060] In addition to reducing the amount of reconfiguration required on parts of remote RAN nodes, the connection load balancer provides the flexibility to automatically balance connections across available MME / AMF resources, thereby optimizing resource utilization. For example, the connection load balancer can maintain measurements of the S1 / N2 connection load of MME / AMF instances and use these measurements to make S1 / N2 connection distribution decisions. In the event of a loss of message processing capacity in an MME / AMF node, the connection load balancer can redistribute connections to other MME / AMF instances and provide the same level of service to the remote RAN nodes.

[0061] exist Figure 3 In this configuration, the connection load balancer 300 includes Ethernet interfaces 302 and 304. The connection load balancer 300 only exposes IP addresses IP-Node-A and IP address IP-Node-B to RAN devices, such as RAN node 100. IP addresses IP-Node-1-A, IP-Node-1-B, IP-Node-NA, and IP-Node-NB are not advertised to RAN nodes. As virtual entities, the connection load balancer 300 and / or mobility management node instance 102 can represent virtual machines running on a hypervisor on cloud computing hardware.

[0062] Figure 4 The illustration shows an example of the proposed solution, which uses a connected load balancer for inbound traffic. Figure 4 In this process, the connection load balancer 300 receives S1 / N2 connection requests from RAN node 100, performs load balancing to distribute the requests across MME / AMF instances 102, and forwards the connection requests to the selected MME / AMF 102. Because the IP address of the MME / AMF 102 is not exposed to RAN node 100, scaling up or down the MME / AMF instance 102 can be seamlessly handled at the connection load balancer 300 if needed, as described in more detail below. IP address IP-Node-A is advertised to RAN node 100 and other RAN nodes on network A. RAN node 100 and other RAN nodes on network A use IP address IP-Node-A as the destination IP address for ingress S1 / N2 connections on network A, where the ingress direction is from the RAN node to the MME / AMF instance. IP address IP-Node-B is advertised to RAN node 100 and other RAN nodes on network B. RAN node 100 and other nodes on network B use the IP address IP-Node-B as the destination IP address for the entry S1 / N2 connection on network B.

[0063] Figure 5The diagram illustrates the path of outbound traffic using a network that includes a connected load balancer 300. Figure 5 As can be seen, outbound traffic travels from MME / AMF instance 102 to RAN node 100 without passing through load balancer 300. In this example, the outbound direction refers to the direction from the MME / AMF instance to the RAN node. Outbound traffic from the MME / AMF instance will not pass through load balancer 300 because the outbound traffic is addressed to the IP address of the remote RAN node obtained from the inbound message from the remote RAN node.

[0064] Figure 6A and 6B The diagram illustrates the initialization phase of connecting the load balancer 300. Figure 6A In step A.1, the border gateway 600, connected between RAN node 100 and the load balancer 300, receives a broadcast gratuitous Address Resolution Protocol (ARP) message or an ICMPv6 neighbor discovery message from the load balancer 300. The broadcast gratuitous ARP message or ICMPv6 neighbor discovery message associates IP addresses IP-Node-A and IP-Node-B with Media Access Control (MAC) addresses MAC-A and MAC-B, respectively. In step A.2, the border gateway 600 updates its MAC table to associate IP addresses IP-Node-A and IP-Node-B with MAC addresses MAC-A and MAC-B, respectively. It should be noted that MAC addresses MAC-A and MAC-B are associated with the Ethernet interfaces 302 and 304 of the load balancer 300, not with the MME / AMF instance.

[0065] Figure 6B The diagram illustrates the steps for configuring an MME / AMF instance. (Reference) Figure 6BIn step B.1, each MME / AMF instance configures alias IP addresses IP-Node-A and IP-Node-B on its loopback interface. Since the loopback interface has no MAC address, these MME / AMF interfaces do not send ARP messages and ICMPv6 neighbor discovery messages. In step B.2, each MME / AMF instance configures a multi-homed responder connection that begins listening for incoming S1 / N2 connection requests on the address IP-Node-A for the primary path and the address IP-Node-B for the secondary path. As indicated above, IP addresses IP-Node-A and IP-Node-B are associated with the MAC addresses MAC-A and MAC-B of the connection load balancer 300. Because remote RAN nodes use IP addresses IP-Node-A and IP-Node-B to connect to multiple different MME / AMF instances, and the connection load balancer determines which MME / AMF instance should handle a given connection request, MME / AMF instances can be reconfigured without requiring remote RAN nodes to reconfigure their S1 / N2 connections as a result of reconfiguration.

[0066] As described above, one function that the connection load balancer 300 can perform is to distribute S1 / N2 connections from remote RAN nodes between MME / AMF instances. Figure 7 This is a message flow diagram illustrating examples of messages that can be exchanged within the connection distribution algorithm implemented by the connection load balancer 300. (Reference) Figure 7 In step C.1, an S1 / N2 connection request for connection-1 with destination IP address {IP-Node-A, IPNode-B}, source IP address {R-IP-x, R-IP-y} and destination port P1 arrives from the remote RAN node.

[0067] In step C.2, border gateway 600 queries its MAC table for {IP-Node-A, IP-Node-B} and forwards the connection request for connection-1 to connection load balancer 300. In step C.3, connection load balancer 300 applies a connection distribution algorithm to determine the MME / AMF instance to which the connection request should be forwarded. In one exemplary implementation, connection load balancing is performed based on the following parameters:

[0068] - Group: Represents all connections from a specific peer (i.e., RAN node).

[0069] - Group count (i.e., the count of connections from remote RAN nodes for each MME / AMF instance in each group) - is initialized to zero for all MME / AMF instances.

[0070] - Connection Distribution Threshold (Cross-Group Valid)- MME / AMF instances whose group count differs from the lowest group count by a value equal to or greater than this value will not be considered as candidates to receive new connection requests. For example, if MME / AMF instances 1, 2, and 3 have group counts of 1, 2, and 3, respectively, and the connection distribution threshold is 2, then MME / AMF instances 1 and 2 will be considered as candidates to receive new connection requests. MME / AMF instance 1 has the lowest group count, so the group count difference is 1 - 1 = 0, which is less than the connection distribution threshold 2. The group count difference of MME / AMF instance 2 relative to MME / AMF instance 1 is 2 - 1 = 1, which is less than the connection distribution threshold 2. The group count difference of MME / AMF instance 3 relative to MME / AMF instance 1 is 3 - 1 = 2. Since 2 equals the connection distribution threshold, MME / AMF instance 3 will not be considered as a candidate to receive new connection requests.

[0071] When multiple MME / AMF instances have a group count difference less than the connection distribution threshold, the connection load balancer 300 can select from available candidates using any suitable parameters, such as the instance identifiers of the MME / AMF instances being ordered in ascending order. Continuing the previous example, if MME / AMF instances 1 and 2 are candidates for a new connection request, then MME / AMF instance 1 can be selected for the new connection request before MME / AMF instance 2 based on the ascending order of the instance identifiers.

[0072] Once the connection load balancer 300 identifies the MME / AMF instance to which the connection request should be forwarded, the connection load balancer 300 can perform the following steps:

[0073] -Increment the group count of MME / AMF instance -i (MME / AMF instance i is the MME / AMF instance to which the connection load balancer 300 should forward the connection load balancer)

[0074] - Create associated records in its cache to ensure protocol continuity:

[0075] In this example, the association record associates the source IP address and source port of the remote peer with the destination IP address of the MME / AMF instance. Symbolically, the association record could be as follows: {Src-IP, Src-Port, Dest-IP (MME / AMF instance)}. Figure 5 In this context, the destination IP address of interest for the MME / AMF is IP-Node-A-1, which is the IP address of the MME / AMF instance, and is different from the alias IP-Node-A published by the connection load balancer 300.

[0076] In step C.4, the connection load balancer 300 forwards the connection request to the MME / AMF instance-i determined in step C.3.

[0077] In step C.5, MME / AMF instance-i accepts the connection. The response is sent directly to the remote peer via the border gateway. The connection load balancer is no longer in the return path used to send messages from MME / AMF instance-i to RAN node 100.

[0078] Figure 8 This is a message flow diagram illustrating signaling for call continuity in a network including a connected load balancer 300. (Reference) Figure 8 In step D.1, the S1 / N2 message arrives at connection-1, which has a destination IP address {IP-Node-A, IP-Node-A}, a source IP address {R-IP-x, R-IP-y}, and a destination port P1.

[0079] In step D.2, the border gateway 600 queries its MAC table to obtain {IP-Node-A, IP-Node-B} and forwards the S1 / N2 message on connection-1 to the connection load balancer 300. In this example, it is assumed that the connection request for connection-1 has been processed as described above.

[0080] In step D.3, the connection load balancer 300 queries its association database (in cache memory) to determine the MME / AMF instance to which the connection load balancer 300 previously forwarded the connection request message. In this example, it is assumed that the following association records exist in the association database maintained by the connection load balancer 300:

[0081] {R-IP-x,P1,MME / AMF instance-i)}→MME / AMF instance-i.

[0082] This entry is created by the connection load balancer 300 in its associated database based on the application of the connection request using the load balancing algorithm, as described above.

[0083] In step D.4, the connection load balancer 300 forwards the message to the MME / AMF instance-i determined in step D.3.

[0084] In step D.5, MME / AMF instance-i receives the message, processes the message, prepares a response, and sends the response over the same connection. The response is sent directly to the remote peer via border gateway 600. Connection load balancer 300 is not in the forwarding path used to send messages from MME / AMF instance 102 to RAN node 100.

[0085] Figure 9This is a diagram illustrating RAN connection reconstruction. Figure 9 In step 1, MME / AMF instance 1 102 serving S1 / N2 connection 1 crashes. In step 2, S1 / N2 connection 1 connected to MME / AMF instance 1 102 is disconnected. In step 3, remote RAN node 100 attempts to rebuild S1 / N2 connection 1. Connection load balancer 300 reroutes the connection request to MME / AMF instance -i based on the connection distribution algorithm described above. Remote RAN node 100 does not need to know the IP address of the new MME / AMF instance to which the connection is rerouted. Remote RAN node 100 sends a reconnection request on behalf of the MME / AMF instance to the alias IP address published by connection load balancer 300, and connection load balancer 300 uses its connection distribution algorithm to select an MME / AMF instance to handle the connection rebuild request.

[0086] Figure 10 This is a block diagram illustrating an exemplary connection of a load balancer. (Reference) Figure 10 The connection load balancer 300 includes at least one processor 1000 and a memory 1002. An S1 / N2 connection distributor 1004 may be implemented in software stored in the memory 1002 to perform the S1 / N2 connection distribution steps described herein. The connection load balancer 300 also includes signaling or Ethernet interfaces 302 and 304 for receiving incoming S1 / N2 connection requests from RAN nodes. In one example, the connection load balancer 300 associates the MAC addresses of the signaling interfaces 302 and 304 with published IP addresses that are also associated with the loopback interface of the MME / AMF instance 102. The connection load balancer 300 may also include an S1 / N2 association cache or database 1006, which is at least partially populated by the connection load balancer 300 with associations between the IP addresses of the selected MME / AMF instance 102 and the remote RAN peer IP addresses and ports. For example, the S1 / N2 connection distributor 1004 can create an association in the S1 / N2 association database or cache 1006 between the IP address of the MME / AMF instance 102 assigned to the connection and the IP address and port of the remote RAN node extracted from the source IP address and port fields of the connection management message.

[0087] Figure 11 This is a flowchart illustrating an exemplary method that can be implemented by a connection load balancer 300 when distributing the S1 / N2 connection to a mobility management node. (See reference) Figure 11At step 1100, the method includes the connection load balancer publishing an Internet Protocol (IP) address for receiving S1 / N2 connection requests and ingress messages from RAN nodes. For example, the S1 / N2 connection distributor 1004 of the connection load balancer 300 may broadcast a gratuitous ARP message or an ICMPv6 neighbor discovery message that associates the published IP address with the MAC address of the connection load balancer's signaling interface at the border gateway. Figure 5 and 6A Taking IP address IP-Node-A as an example, the load balancer 300 sends a gratuitous ARP message or ICMPv6 neighbor discovery message to the border gateway 600. This message associates IP address IP-Node-A with MAC address MAC-A, which is the MAC address of the signaling interface SIG-A 302 connecting to the load balancer 300. Each MME / AMF instance 102 configures its loopback interface with IP address IP-Node-A as an alias address. The loopback interface is used to add published IP addresses as aliases on the MME / AMF instance because the loopback interface does not have a MAC address, and if an ARP request or ICMPv6 neighbor discovery request is received for an IP address configured as an alias on the loopback interface, no ARP reply or ICMPv6 neighbor discovery message response is sent. Therefore, multiple MME / AMF instances can be configured with the same published IP address without network conflicts. The reason why IP addresses IP-Node-A and IP-Node-B are configured as aliases on the loopback interface of the MME / AMF instance is to bind the transport layer to these addresses so that the MME / AMF instance will listen for S1 / N2 connection requests on this port.

[0088] Return to Figure 11 In step 1102, the method further includes maintaining a connection load measurement for each group of mobility management node instances by a connection load balancer. In one example, the connection load balancer 300 may maintain a group count for each MME / AMF instance 102 for all configured groups. The group count indicates the number of connections assigned to each MME / AMF instance 102 for each group. Other load measurements may be used without departing from the scope of the subject matter described herein.

[0089] In step 1104, the method further includes receiving, at the connection load balancer, a connection request message generated by a remote peer RAN node for initiating a connection with one of the mobility management node instances. For example, if the mobility management node instance is an MME, the connection request could be an S1 connection request. If the mobility management node instance is an AMF, the connection request could be an N2 connection request.

[0090] In step 1106, the method further includes the connection load balancer applying a connection distribution algorithm to select a mobility management node instance to handle connection request messages, and the connection load balancer creating an association between the IP address of the selected mobility management node instance and the IP address and port of the remote RAN peer extracted from the source IP address and source port of the connection request message in a database at least partially populated by the connection load balancer for protocol continuity. For example, the connection distribution algorithm may select an MME / AMF instance from MME / AMF instances whose group count difference exceeds a connection assignment threshold to receive new S1 or N2 connection requests. The connection load balancer 300 may create an association between the published IP address associated with the selected MME or AMF instance and the IP address and port of the remote RAN peer in the S1 / N2 association cache or database 306. Figure 5 As an example, the association can be between the IP address and port of RAN node 100 and the IP address IP-Node-A published by one of the MME / AMF instances 102 selected to handle the connection.

[0091] In step 1108, the method further includes forwarding the connection request message to the mobility management node instance selected using a connection distribution algorithm by the connection load balancer. For example, the connection load balancer 300 may forward the connection request to the MME / AMF instance selected in step 1106 and update the group count of the MME / AMF instance. The connection load balancer creates an association record in its cache to ensure protocol continuity by forwarding subsequent messages on this S1 / N2 connection to this MME / AMF instance. In messages transmitted to the MME / AMF instance, the connection load balancer may include its MAC address as the source MAC address.

[0092] advantage

[0093] The connection load balancer described in this article offers at least the following advantages:

[0094] The connection load balancer described in this article can be used to distribute S1 / N2 connections between MME / AMF instances, which reduces the impact of changes to the MME / AMF configuration on the sending node. That is, when an MME / AMF instance goes down or if a new MME / AMF instance is created, the sending node or remote peer does not need to rebuild the connection with the new IP address.

[0095] A connection load balancer can be used to solve this problem by using a single interface to a remote peer and managing the internal interfaces, regardless of whether an S1 / N2 connection is set up using one IP interface card or multiple interface cards.

[0096] Positioning the connection load balancer upstream of the MME / AMF node in a cloud / on-premises environment offers the following advantages:

[0097] When MME / AMF nodes are expanded or shrunk, the reconfiguration of remote nodes has little impact.

[0098] Automatic load balancing of S1 / N2 traffic to optimize the use of cloud resources; and

[0099] High redundancy can be achieved without extensive external configuration of the remote peer component.

[0100] It will be understood that various details of this disclosure may be changed without departing from the scope of the subject matter. Furthermore, the foregoing description is for illustrative purposes only and not for limiting purposes.

Claims

1. A method for distributing connections to mobility management node instances, the method comprising: The connection load balancer publishes an Internet Protocol (IP) address for receiving connection requests and ingress messages from Radio Access Network (RAN) nodes, wherein the IP address is an alias IP address associated with the loopback interface of the mobility management node instance, and the mobility management node instance listens for messages addressed to the alias IP address; The connection load measurement of the mobility management node instance is maintained by the connection load balancer; The connection load balancer receives a connection request message generated by the RAN node for initiating a connection with one of the mobility management node instances, the connection request message being addressed to one of the alias IP addresses; The connection load balancer applies a connection distribution algorithm to select a mobility management node instance to handle the connection request message; The connection load balancer creates an association between the IP address of the selected mobility management node instance and the IP address and port of the RAN node extracted from the source IP address and source port fields of the connection request message, in a cache or database at least partially filled by the connection load balancer for protocol continuity. as well as The connection request message is forwarded by the connection load balancer to the mobility management node instance selected using the connection distribution algorithm.

2. The method of claim 1, comprising: Receive subsequent messages on the connection at the connection load balancer; The source IP address and source port extracted from the subsequent message are used to query the cache or database to determine the IP address of the mobility management node instance serving the connection; as well as The connection load balancer forwards the subsequent messages to the IP address of the mobility management node instance.

3. The method of claim 1 or claim 2, wherein publishing the IP address comprises broadcasting a gratuitous Address Resolution Protocol (ARP) message or an Internet Control and Management Protocol version 6 (ICMPv6) neighbor discovery message to the border gateway node, the message associating each published IP address with the Media Access Control (MAC) address of the interface connected to the load balancer.

4. The method of claim 1 or claim 2, wherein the mobility management node instance includes a mobility management entity (MME) instance or an access and mobility management function (AMF) instance, and wherein receiving the connection request message includes receiving an S1 or N2 connection request message.

5. The method of claim 1 or claim 2, wherein maintaining connection load information includes maintaining a group count for each of the mobility management node instances, wherein the group count includes a count of the number of connections to the mobility management node instance, and selecting a mobility management node instance includes selecting a mobility management node instance using the group count.

6. The method of claim 1 or claim 2, comprising detecting a failure in one of the mobility management node instances and automatically routing the connection request message to an available mobility management node instance.

7. The method of claim 6, further comprising detecting the reconstruction of the mobility management node instance, and wherein applying the connection distribution algorithm comprises including the reconstructed mobility management node instance as a selection candidate for the connection distribution algorithm.

8. The method of claim 1 or claim 2, further comprising detecting the availability of a new mobility management node instance, and wherein applying the connection distribution algorithm comprises including the new mobility management node instance as a selection candidate for the connection distribution algorithm.

9. A system for distributing connections to mobility management node instances, the system comprising: Connect to a load balancer, including at least one processor and memory; as well as The S1 / N2 connection distributor, implemented by the at least one processor, is used for: Publish an Internet Protocol (IP) address for receiving connection requests and ingress messages from Radio Access Network (RAN) nodes, wherein the IP address is an alias IP address associated with the loopback interface of the Mobility Management Node instance, and the Mobility Management Node instance listens for messages addressed to the alias IP address; Maintain connection load measurement for the mobility management node instance; Receive a connection request message generated by the RAN node for initiating a connection with one of the mobility management node instances, the connection request message being addressed to one of the alias IP addresses; A connection distribution algorithm is applied to select a mobility management node instance to handle the connection request message; For protocol continuity, an association is created between the IP address of the selected mobility management node instance and the IP address and port of the RAN node extracted from the source IP address and source port fields of the connection request message; as well as The connection request message is forwarded to the selected mobility management node instance.

10. The system of claim 9, wherein the S1 / N2 connection distributor is further configured to: Receive subsequent messages on the connection at the connection load balancer; The source IP address and source port extracted from the subsequent message are used to query the cache or database to determine the IP address of the mobility management node instance serving the connection; and The connection load balancer forwards the subsequent messages to the IP address of the mobility management node instance.

11. The system of claim 9 or claim 10, wherein publishing the IP address comprises broadcasting a gratuitous Address Resolution Protocol (ARP) message or an Internet Control and Management Protocol version 6 (ICMPv6) neighbor discovery message to a border gateway node, the message associating the IP address of the connected load balancer with the Media Access Control (MAC) address of the interface connected to the load balancer.

12. The system of claim 9 or claim 10, wherein the mobility management node instance includes a mobility management entity (MME) instance or an access and mobility management function (AMF) instance, and wherein receiving the connection request message includes receiving an S1 or N2 connection request message.

13. The system of claim 9 or claim 10, wherein maintaining connection load information includes maintaining a group count for each of the mobility management node instances, wherein the group count includes a count of the number of connections to the mobility management node instance, and wherein selecting a mobility management node instance includes selecting a mobility management node instance using the group count.

14. The system of claim 9 or claim 10, wherein the S1 / N2 connection distributor is configured to detect a failure in one of the mobility management node instances and automatically route the connection request message to an available mobility management node instance.

15. The system of claim 14, wherein the S1 / N2 connection distributor is configured to detect the reconstruction of the mobility management node instance, and wherein applying the connection distribution algorithm includes including the reconstructed mobility management node instance as a selection candidate of the connection distribution algorithm.

16. The system of claim 9 or claim 10, wherein the S1 / N2 connection distributor is configured to detect the availability of a new mobility management node instance, and wherein applying the connection distribution algorithm includes including the new mobility management node instance as a selection candidate of the connection distribution algorithm.

17. A non-transitory computer-readable medium storing executable instructions thereon, the instructions controlling the computer to perform steps when executed by a computer's processor, including: The connection load balancer publishes an Internet Protocol (IP) address for receiving connection requests and ingress messages from Radio Access Network (RAN) nodes directed to a Mobility Management Node instance, wherein the IP address is an alias IP address associated with the loopback interface of the Mobility Management Node instance, and the Mobility Management Node instance listens for messages addressed to the alias IP address. The connection load measurement of the mobility management node instance is maintained by the connection load balancer; The connection load balancer receives a connection request message generated by the RAN node for initiating a connection with one of the mobility management node instances, the connection request message being addressed to one of the alias IP addresses; The connection load balancer applies a connection distribution algorithm to select a mobility management node instance to handle the connection request message; The connection load balancer creates an association between the IP address of the selected mobility management node instance and the IP address and port of the RAN node extracted from the source IP address and source port fields of the connection request message, in a cache or database at least partially filled by the connection load balancer for protocol continuity. as well as The connection request message is forwarded to the mobility management node instance selected using the connection distribution algorithm.

18. The non-transitory computer-readable medium of claim 17, comprising: Receive subsequent messages on the connection at the connection load balancer; The source IP address and source port extracted from the subsequent message are used to query the cache or database to determine the IP address of the mobility management node instance serving the connection; as well as The connection load balancer forwards the subsequent messages to the IP address of the mobility management node instance.

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