5G LAN三模式转发与VN组通信信令拆解

classDiagram
    class VNGroup {
        +ExternalGroupId
        +GroupId
        +DNN
        +S_NSSAI
        +PduSessionType : Ethernet
        +AppLayerGroupId
        +Members[] : SUPI列表
        +DefaultCommunication
    }
    class UDM {
        +GroupIdentificationData
        +SubscriberDataManagement
    }
    class AF {
        +GroupCreation
        +MemberAddition
        +MemberRemoval
        +GroupDeletion
    }
    class NEF {
        +Authorization
        +Mapping_External_to_Internal
    }
    AF --> NEF : Nnef_GroupManagement
    NEF --> UDM : Nudm_GroupManagement
    UDM --> VNGroup : 存储/检索

sequenceDiagram
    participant AF
    participant NEF
    participant UDM
    participant UDR
    participant PCF

    AF->>NEF: Nnef_GroupManagement_Create Request<br/>ExternalGroupId, DNN, S-NSSAI, Members[]
    NEF->>NEF: 授权检查（TS 23.502 4.13.8.1）
    NEF->>UDM: Nudm_GroupManagement_Create<br/>GroupId, DNN, S-NSSAI, Members[SUPI]
    UDM->>UDR: Nudr_DataRepository_Create<br/>写入GroupData
    UDR-->>UDM: 201 Created
    UDM-->>NEF: GroupId, 成员确认
    NEF-->>AF: ExternalGroupId, 创建确认

    Note over PCF: 可选：AF通过NEF触发<br/>PCF策略更新
    AF->>NEF: Nnef_PolicyAuthorization<br/>VN Group QoS策略
    NEF->>PCF: Npcf_PolicyAuthorization
    PCF->>PCF: 生成PCC规则含5G VN参数

sequenceDiagram
    participant UE
    participant RAN as gNB
    participant AMF
    participant SMF
    participant UDM
    participant PCF
    participant UPF1 as PSA UPF1
    participant UPF2 as PSA UPF2

    UE->>AMF: NAS PDU Session Establishment Request<br/>DNN=vn-group1, S-NSSAI, PDU Type=Ethernet
    AMF->>SMF: Nsmf_PDUSession_CreateSMContext Request<br/>DNN, S-NSSAI, SUPI

    SMF->>UDM: Nudm_SDM_Get<br/>获取SM Subscription Data
    UDM-->>SMF: 5G VN Group信息<br/>GroupId, MemberList[], DefaultCommunication

    SMF->>SMF: 检查UE是否为VN Group成员<br/>查询VN Group Membership

    alt UE不是VN Group成员
        SMF-->>AMF: 拒绝PDU会话建立
    else UE是成员
        SMF->>PCF: Npcf_SMPolicyControl_Create<br/>含VN Group ID
        PCF-->>SMF: PCC Rules + VN Group策略

        SMF->>SMF: UPF选择决策<br/>检查VN Group现有PDU会话分布

        alt 存在同UPF的其他组成员
            SMF->>UPF1: N4 Session Establishment<br/>PDR + FAR (Local Switch规则)
            UPF1-->>SMF: N4 Session Response
        else 需要N19连接
            SMF->>UPF1: N4 Session Establishment<br/>PDR + FAR (N19转发规则)
            SMF->>UPF2: Group-level N4 Session<br/>建立N19隧道端点
            UPF2-->>SMF: N4 Session Response
        end

        SMF-->>AMF: Nsmf_PDUSession_CreateSMContext Response<br/>含N2 SM Info (AN Tunnel Info)
        AMF->>RAN: N2 PDU Session Resource Setup
        RAN->>UE: RRC Reconfiguration<br/>DRB配置
        RAN-->>AMF: N2 PDU Session Resource Setup Response
        AMF->>SMF: Nsmf_PDUSession_UpdateSMContext<br/>AN Tunnel Info

        SMF->>UPF1: N4 Session Modification<br/>激活下行FAR
    end

graph LR
    subgraph UPF["PSA UPF"]
        PDR1["PDR1<br/>UE-A PDU Session"]
        PDR2["PDR2<br/>UE-B PDU Session"]
        FAR1["FAR1<br/>Forward to UE-B"]
        FAR2["FAR2<br/>Forward to UE-A"]
        BUF["Bridge Function<br/>二层学习/转发"]
    end
    UE1["UE-A<br/>MAC: AA:BB"] --> PDR1
    PDR1 --> BUF
    BUF --> FAR1
    FAR1 --> UE2["UE-B<br/>MAC: CC:DD"]
    UE2 --> PDR2
    PDR2 --> BUF
    BUF --> FAR2
    FAR2 --> UE1

    style UPF fill:#e1f5fe
    style BUF fill:#fff3e0

PDR ID: 1
Precedence: 100
PDI:
  Source Interface: ACCESS (UL)
  F-TEID: UE-A的N3 F-TEID
  Ethernet Filter:
    Source MAC: UE-A MAC
Outer Header Removal: Yes (GTP-U)
FAR ID: 1  → 关联FAR1

FAR ID: 1
Apply Action: FORW
Forwarding Parameters:
  Destination Interface: ACCESS (DL)
  Network Instance: [ VN Group DNN ]
  Outer Header Creation: GTP-U with UE-B的N3 F-TEID
  5G VN Group Info:
    Local Switching: true

sequenceDiagram
    participant SMF
    participant UPF1 as PSA UPF1
    participant UPF2 as PSA UPF2

    Note over SMF: 检测到VN Group成员<br/>分布在两个UPF

    SMF->>UPF1: PFCP Session Establishment Request<br/>Group-level N4会话<br/>Create PDR + FAR (N19)
    Note right of UPF1: FAR配置:<br/>Destination=N19<br/>Tunnel Endpoint=UPF2 N19 TEID
    UPF1-->>SMF: PFCP Session Establishment Response<br/>N19 F-TEID

    SMF->>UPF2: PFCP Session Establishment Request<br/>Group-level N4会话<br/>Create PDR + FAR (N19)
    Note right of UPF2: FAR配置:<br/>Destination=N19<br/>Tunnel Endpoint=UPF1 N19 TEID
    UPF2-->>SMF: PFCP Session Establishment Response<br/>N19 F-TEID

    SMF->>UPF1: PFCP Session Modification<br/>更新FAR中UPF2的N19 TEID
    SMF->>UPF2: PFCP Session Modification<br/>更新FAR中UPF1的N19 TEID

    Note over UPF1,UPF2: N19隧道建立完成<br/>双向转发就绪

sequenceDiagram
    participant SMF1
    participant SMF2
    participant UPF1 as PSA UPF1<br/>(SMF1管辖)
    participant UPF2 as PSA UPF2<br/>(SMF2管辖)

    Note over SMF1: 新UE建立PDU会话<br/>发现VN Group成员在SMF2

    SMF1->>SMF2: Nsmf_PDUSession_N19Info<br/>Request: 请求N19隧道建立<br/>GroupId, UPF1 N19能力
    SMF2->>SMF2: 验证VN Group成员关系<br/>查询Group-level N4会话状态

    SMF2->>UPF2: PFCP Session Modification<br/>Group-level N4会话<br/>添加到UPF1的N19 FAR
    UPF2-->>SMF2: N19 F-TEID (UPF2侧)

    SMF2-->>SMF1: Nsmf_PDUSession_N19Info<br/>Response: UPF2 N19 TEID

    SMF1->>UPF1: PFCP Session Establishment/Modification<br/>Group-level N4会话<br/>配置到UPF2的N19 FAR
    Note right of UPF1: FAR: Forward to N19<br/>Remote TEID = UPF2 N19 TEID
    UPF1-->>SMF1: N19 F-TEID (UPF1侧)

    SMF1->>SMF2: Nsmf_PDUSession_N19Info<br/>Notification: UPF1 N19 TEID
    SMF2->>UPF2: PFCP Session Modification<br/>更新FAR中UPF1 N19 TEID

    Note over UPF1,UPF2: N19隧道双向就绪

graph TD
    subgraph PFCP规则架构
        PDR["PDR: 匹配组播帧<br/>Destination MAC = 组播地址"]
        MAR["MAR: 组播复制规则"]
        FAR1["FAR1: → UE-A<br/>Local Switch"]
        FAR2["FAR2: → UE-B<br/>Local Switch"]
        FAR3["FAR3: → UPF2<br/>N19隧道"]
    end

    PDR --> MAR
    MAR --> FAR1
    MAR --> FAR2
    MAR --> FAR3

    style MAR fill:#ffecb3
    style PDR fill:#e1f5fe

sequenceDiagram
    participant AF
    participant NEF
    participant UDM
    participant SMF
    participant UPF

    AF->>NEF: Nnef_GroupManagement_Update<br/>添加新成员SUPI
    NEF->>UDM: Nudm_GroupManagement_Update<br/>MemberList += 新SUPI
    UDM-->>NEF: 更新确认

    UDM->>SMF: Nudm_SDM_Notification<br/>VN Group成员变更通知
    SMF->>SMF: 更新本地VN Group成员缓存

    Note over SMF: 当新成员建立PDU会话时<br/>SMF已有最新成员列表

    SMF->>UPF: PFCP Session Modification<br/>更新现有PDR/FAR的<br/>转发目标列表

stateDiagram-v2
    [*] --> VNGroup_Created: AF/NEF创建VN Group
    VNGroup_Created --> Active: 首个成员PDU会话建立
    Active --> Active: 成员加入/离开
    Active --> Active: N19隧道建立/释放
    Active --> Active: PFCP规则更新
    Active --> Idle: 最后一个成员PDU会话释放
    Idle --> Active: 新成员PDU会话建立
    Idle --> VNGroup_Deleted: AF/NEF删除VN Group
    VNGroup_Deleted --> [*]

    state Active {
        [*] --> NoSession
        NoSession --> SingleUPF: 1个UPF有成员
        SingleUPF --> MultiUPF: 新UPF有成员加入
        MultiUPF --> SingleUPF: 某UPF最后成员离开
        SingleUPF --> NoSession: 最后成员释放
    }