Hybrid and Hierarchical OAM Architecture

Table of Contents

1 Scope
2 Objectives
3 Use Case Description
- 3.1 Introduction
4 Implementation
5 References

Subpages

Scope

This page describes the target use case for the OAM project to be demonstrated at the O-RAN Alliance face to face meeting in Montreal in the week Oct28 2024.

Objectives

This page is a working document to discussed and design the use cases and its components.

Use Case Description

Introduction

The O-RAN Alliance specifies two architectures or communications flows from O-RUs to the SMO for management traffic.

hierarchical All management traffic (OpenFronthaul Management Plane, OFHM) terminates at the O-DU. SMO OAM functions communicate with the O-RU only indirectly via the O-DU with the O-RU. Therefore the operations on O-RU data models are exposed by the O-DU using the RFC8528 YANG Schema Mount concept.
hybrid In such architecture some management traffic can by-pass the O-DU. SMO OAM functions can directly access the NETCONF Client of the O-RU. A typical use cases is software management. Which management traffic can by-pass the O-RU is handled by the Access Control configuration of the O-RU.

Implementation

The generated topology for about 7000 NRCellDus is too big to discuss the details of hierarchical and hybrid OAM Architectures.

We just need two O-RUs - let’s assume each O-RU implements just one NRCellDU and that the related O-DU in an edge cloud at the next tower.

The following figure shows 2 cells at one tower. At a second tower the O-DU-Edge-Cloud is located. Both towers are visualized as a dot. The cells are visualized by as polygon show the coverage. The overlap between both cells are for handover.

In this simple topology we have two towers with just 3 RAN nodes

1x O-DU at the top of the image
2x O-RUs at the bottom of the image.

We assume that the O-Cloud resource pools for O-CU, Near-RT-Ric, 5G-Core and SMO are also located close to the northern tower.

The topology described according ietf-network-topology as json encoding (RFC7951) looks like this:

{
  "ietf-network:networks": {
    "network": [
      {
        "network-id": "be5229af-2660-4bae-8f2c-b9d0f788fad1",
        "node": [
          {
            "node-id": "O-RAN-SMO",
            "ietf-network-topology:termination-point": [
              {
                "tp-id": "O-RAN-SMO-PHY"
              },
              {
                "tp-id": "O-RAN-SMO-A1"
              },
              {
                "tp-id": "O-RAN-SMO-O1"
              },
              {
                "tp-id": "O-RAN-SMO-O2"
              }
            ]
          },
          {
            "node-id": "O-RAN-NearRtRic-00",
            "ietf-network-topology:termination-point": [
              {
                "tp-id": "O-RAN-NearRtRic-00-PHY"
              },
              {
                "tp-id": "O-RAN-NearRtRic-00-A1"
              },
              {
                "tp-id": "O-RAN-NearRtRic-00-O1"
              },
              {
                "tp-id": "O-RAN-NearRtRic-00-O2"
              },
              {
                "tp-id": "O-RAN-NearRtRic-00-E2"
              }
            ]
          },
          {
            "node-id": "O-RAN-CU-00-00",
            "ietf-network-topology:termination-point": [
              {
                "tp-id": "O-RAN-CU-00-00-PHY"
              },
              {
                "tp-id": "O-RAN-CU-00-00-E2"
              },
              {
                "tp-id": "O-RAN-CU-00-00-O1"
              }
            ]
          },
          {
            "node-id": "O-RAN-O-Cloud-DU-00-00-00",
            "ietf-network-topology:termination-point": [
              {
                "tp-id": "O-RAN-O-Cloud-DU-00-00-00-PHY"
              },
              {
                "tp-id": "O-RAN-O-Cloud-DU-00-00-00-O2"
              }
            ]
          },
          {
            "node-id": "O-RAN-Tower-00-00-00-00",
            "ietf-network-topology:termination-point": [
              {
                "tp-id": "O-RAN-O-Cloud-DU-00-00-00-O2"
              }
            ]
          },
          {
            "node-id": "O-RAN-Tower-00-00-00-05",
            "ietf-network-topology:termination-point": []
          },
          {
            "node-id": "O-RAN-DU-00-00-00-05-00",
            "ietf-network-topology:termination-point": [
              {
                "tp-id": "O-RAN-DU-00-00-00-05-00-PHY"
              },
              {
                "tp-id": "O-RAN-DU-00-00-00-05-00-E2"
              },
              {
                "tp-id": "O-RAN-DU-00-00-00-05-00-O1"
              },
              {
                "tp-id": "O-RAN-DU-00-00-00-05-00-OFHM"
              },
              {
                "tp-id": "O-RAN-DU-00-00-00-05-00-OFHC"
              },
              {
                "tp-id": "O-RAN-DU-00-00-00-05-00-OFHU"
              },
              {
                "tp-id": "O-RAN-DU-00-00-00-05-00-OFHS"
              }
            ]
          },
          {
            "node-id": "O-RAN-RU-00-00-00-05-01",
            "ietf-network-topology:termination-point": [
              {
                "tp-id": "O-RAN-RU-00-00-00-05-01-PHY"
              },
              {
                "tp-id": "O-RAN-RU-00-00-00-05-01-OFHM"
              },
              {
                "tp-id": "O-RAN-RU-00-00-00-05-01-OFHC"
              },
              {
                "tp-id": "O-RAN-RU-00-00-00-05-01-OFHU"
              },
              {
                "tp-id": "O-RAN-RU-00-00-00-05-01-OFHS"
              },
              {
                "tp-id": "O-RAN-NRCellDu-00-00-00-05-01-00"
              }
            ]
          },
          {
            "node-id": "O-RAN-RU-00-00-00-05-02",
            "ietf-network-topology:termination-point": [
              {
                "tp-id": "O-RAN-RU-00-00-00-05-02-PHY"
              },
              {
                "tp-id": "O-RAN-RU-00-00-00-05-02-OFHM"
              },
              {
                "tp-id": "O-RAN-RU-00-00-00-05-02-OFHC"
              },
              {
                "tp-id": "O-RAN-RU-00-00-00-05-02-OFHU"
              },
              {
                "tp-id": "O-RAN-RU-00-00-00-05-02-OFHS"
              },
              {
                "tp-id": "O-RAN-NRCellDu-00-00-00-05-02-00"
              }
            ]
          }
        ]
      }
    ],
    "ietf-network-topology:link": [
      {
        "link-id": "phy:O-RAN-NearRtRic-00<->O-RAN-SMO",
        "source": {
          "source-node": "O-RAN-NearRtRic-00",
          "source-tp": "O-RAN-NearRtRic-00-PHY"
        },
        "destination": {
          "dest-node": "O-RAN-SMO",
          "dest-tp": "O-RAN-SMO-PHY"
        }
      },
      {
        "link-id": "phy:O-RAN-CU-00-00<->O-RAN-NearRtRic-00",
        "source": {
          "source-node": "O-RAN-CU-00-00",
          "source-tp": "O-RAN-CU-00-00-PHY"
        },
        "destination": {
          "dest-node": "O-RAN-NearRtRic-00",
          "dest-tp": "O-RAN-NearRtRic-00-PHY"
        }
      },
      {
        "link-id": "phy:O-RAN-O-Cloud-DU-00-00-00<->O-RAN-CU-00-00",
        "source": {
          "source-node": "O-RAN-O-Cloud-DU-00-00-00",
          "source-tp": "O-RAN-O-Cloud-DU-00-00-00-PHY"
        },
        "destination": {
          "dest-node": "O-RAN-CU-00-00",
          "dest-tp": "O-RAN-CU-00-00-PHY"
        }
      },
      {
        "link-id": "phy:O-RAN-DU-00-00-00-05-00<->O-RAN-CU-00-00",
        "source": {
          "source-node": "O-RAN-DU-00-00-00-05-00",
          "source-tp": "O-RAN-DU-00-00-00-05-00-PHY"
        },
        "destination": {
          "dest-node": "O-RAN-CU-00-00",
          "dest-tp": "O-RAN-CU-00-00-PHY"
        }
      },
      {
        "link-id": "e2:O-RAN-DU-00-00-00-05-00<->O-RAN-CU-00-00",
        "source": {
          "source-node": "O-RAN-DU-00-00-00-05-00",
          "source-tp": "O-RAN-DU-00-00-00-05-00-E2"
        },
        "destination": {
          "dest-node": "O-RAN-CU-00-00",
          "dest-tp": "O-RAN-CU-00-00-E2"
        }
      },
      {
        "link-id": "o1:O-RAN-DU-00-00-00-05-00<->O-RAN-CU-00-00",
        "source": {
          "source-node": "O-RAN-DU-00-00-00-05-00",
          "source-tp": "O-RAN-DU-00-00-00-05-00-O1"
        },
        "destination": {
          "dest-node": "O-RAN-CU-00-00",
          "dest-tp": "O-RAN-CU-00-00-O1"
        }
      },
      {
        "link-id": "phy:O-RAN-DU-00-00-00-05-00<->O-RAN-CU-00-00",
        "source": {
          "source-node": "O-RAN-DU-00-00-00-05-00",
          "source-tp": "O-RAN-DU-00-00-00-05-00-PHY"
        },
        "destination": {
          "dest-node": "O-RAN-CU-00-00",
          "dest-tp": "O-RAN-CU-00-00-PHY"
        }
      },
      {
        "link-id": "e2:O-RAN-DU-00-00-00-05-00<->O-RAN-CU-00-00",
        "source": {
          "source-node": "O-RAN-DU-00-00-00-05-00",
          "source-tp": "O-RAN-DU-00-00-00-05-00-E2"
        },
        "destination": {
          "dest-node": "O-RAN-CU-00-00",
          "dest-tp": "O-RAN-CU-00-00-E2"
        }
      },
      {
        "link-id": "o1:O-RAN-DU-00-00-00-05-00<->O-RAN-CU-00-00",
        "source": {
          "source-node": "O-RAN-DU-00-00-00-05-00",
          "source-tp": "O-RAN-DU-00-00-00-05-00-O1"
        },
        "destination": {
          "dest-node": "O-RAN-CU-00-00",
          "dest-tp": "O-RAN-CU-00-00-O1"
        }
      },
      {
        "link-id": "phy:O-RAN-RU-00-00-00-05-01<->O-RAN-DU-00-00-00-05-00",
        "source": {
          "source-node": "O-RAN-RU-00-00-00-05-01",
          "source-tp": "O-RAN-RU-00-00-00-05-01-PHY"
        },
        "destination": {
          "dest-node": "O-RAN-DU-00-00-00-05-00",
          "dest-tp": "O-RAN-DU-00-00-00-05-00-PHY"
        }
      },
      {
        "link-id": "ofhm:O-RAN-RU-00-00-00-05-01<->O-RAN-DU-00-00-00-05-00",
        "source": {
          "source-node": "O-RAN-RU-00-00-00-05-01",
          "source-tp": "O-RAN-RU-00-00-00-05-01-OFHM"
        },
        "destination": {
          "dest-node": "O-RAN-DU-00-00-00-05-00",
          "dest-tp": "O-RAN-DU-00-00-00-05-00-OFHM"
        }
      },
      {
        "link-id": "ofhc:O-RAN-RU-00-00-00-05-01<->O-RAN-DU-00-00-00-05-00",
        "source": {
          "source-node": "O-RAN-RU-00-00-00-05-01",
          "source-tp": "O-RAN-RU-00-00-00-05-01-OFHC"
        },
        "destination": {
          "dest-node": "O-RAN-DU-00-00-00-05-00",
          "dest-tp": "O-RAN-DU-00-00-00-05-00-OFHC"
        }
      },
      {
        "link-id": "ofhu:O-RAN-RU-00-00-00-05-01<->O-RAN-DU-00-00-00-05-00",
        "source": {
          "source-node": "O-RAN-RU-00-00-00-05-01",
          "source-tp": "O-RAN-RU-00-00-00-05-01-OFHU"
        },
        "destination": {
          "dest-node": "O-RAN-DU-00-00-00-05-00",
          "dest-tp": "O-RAN-DU-00-00-00-05-00-OFHU"
        }
      },
      {
        "link-id": "ofhs:O-RAN-RU-00-00-00-05-01<->O-RAN-DU-00-00-00-05-00",
        "source": {
          "source-node": "O-RAN-RU-00-00-00-05-01",
          "source-tp": "O-RAN-RU-00-00-00-05-01-OFHS"
        },
        "destination": {
          "dest-node": "O-RAN-DU-00-00-00-05-00",
          "dest-tp": "O-RAN-DU-00-00-00-05-00-OFHS"
        }
      },
      {
        "link-id": "phy:O-RAN-RU-00-00-00-05-02<->O-RAN-DU-00-00-00-05-00",
        "source": {
          "source-node": "O-RAN-RU-00-00-00-05-02",
          "source-tp": "O-RAN-RU-00-00-00-05-02-PHY"
        },
        "destination": {
          "dest-node": "O-RAN-DU-00-00-00-05-00",
          "dest-tp": "O-RAN-DU-00-00-00-05-00-PHY"
        }
      },
      {
        "link-id": "ofhm:O-RAN-RU-00-00-00-05-02<->O-RAN-DU-00-00-00-05-00",
        "source": {
          "source-node": "O-RAN-RU-00-00-00-05-02",
          "source-tp": "O-RAN-RU-00-00-00-05-02-OFHM"
        },
        "destination": {
          "dest-node": "O-RAN-DU-00-00-00-05-00",
          "dest-tp": "O-RAN-DU-00-00-00-05-00-OFHM"
        }
      },
      {
        "link-id": "ofhc:O-RAN-RU-00-00-00-05-02<->O-RAN-DU-00-00-00-05-00",
        "source": {
          "source-node": "O-RAN-RU-00-00-00-05-02",
          "source-tp": "O-RAN-RU-00-00-00-05-02-OFHC"
        },
        "destination": {
          "dest-node": "O-RAN-DU-00-00-00-05-00",
          "dest-tp": "O-RAN-DU-00-00-00-05-00-OFHC"
        }
      },
      {
        "link-id": "ofhu:O-RAN-RU-00-00-00-05-02<->O-RAN-DU-00-00-00-05-00",
        "source": {
          "source-node": "O-RAN-RU-00-00-00-05-02",
          "source-tp": "O-RAN-RU-00-00-00-05-02-OFHU"
        },
        "destination": {
          "dest-node": "O-RAN-DU-00-00-00-05-00",
          "dest-tp": "O-RAN-DU-00-00-00-05-00-OFHU"
        }
      },
      {
        "link-id": "ofhs:O-RAN-RU-00-00-00-05-02<->O-RAN-DU-00-00-00-05-00",
        "source": {
          "source-node": "O-RAN-RU-00-00-00-05-02",
          "source-tp": "O-RAN-RU-00-00-00-05-02-OFHS"
        },
        "destination": {
          "dest-node": "O-RAN-DU-00-00-00-05-00",
          "dest-tp": "O-RAN-DU-00-00-00-05-00-OFHS"
        }
      }
    ]
  }
}

The topology reduced to its minimum to show case the different implementations and connections for hybrid and hierarchical mode is shown in this diagram using the identifiers of the topology above.: