OSS Sandpit – 5G Network Inventory Prototype

5G networks seem to be the big investment trend in telco at the moment. It comes with a lot of tech innovation such as network slicing and an increased use of virtualised network functions (VNFs). This article provides an example of building 5G Network components into the inventory module of our Personal OSS Sandpit Project.

This prototype build includes components such as:

  • Hosting infrastructure
  • NFVI / VIM (NFV Infrastructure and Virtualised Infrastructure Management)
  • A 5GCN (5G Core Network)
  • An IMS (IP Multimedia Subsystem)
  • An RIC (RAN Intelligent Controller)
  • Virtualised Network Functions (AUSF, AMF, NRF, CU, DU, etc – a more extensive list of examples is provided later in this article)
  • Mobile Edge Compute (MEC)
  • MEC Applications like gaming servers, CDN (Content Delivery Networks)
  • Radio Access Network (RAN) and Remote Radio Units (RRU)
  • Outside Plant for fibre fronthaul and backhaul
  • Patching between physical infrastructure
  • End to end circuits between DN (Data Network), IMS, 5GCN, gNodeB, RRU
  • Logical Modelling of 5G Reference Points

Our prototype (a Standalone 5G model) is summarised in the diagram below:

We describe this via the following use-cases:

  • Building Reference Data like data hierarchies, device types, connectivity types, containment, device layouts, templates, flexible data models, etc
  • Creating Device Instances including rack views and the virtualised layers within them
  • Creating Physical Connections between devices
  • Creating Logical Connections between devices
  • Creating Network Slices in the form of services
  • Performing Service Impact Analysis (SIA)

Reference Data

Starting off with the data hierarchy, we had to develop some new building blocks (data classes) to support the virtualisation used in 5G networks. This included some new network slice types, virtualisation concepts and various other things:

In our prototype, we’ve developed a custom containment model as follows:

  • Country
    • Site
      • System (Network Domain)
        • Rack
          • Hosting
            • NFVI / VIM
              • VNF-Groupings (eg CU, DU, MEC, IMS, etc)
                • VNF
                  • Apps (like Gaming Servers)

In a real situation, you probably wouldn’t bother to model to this level of detail as it just makes more data to maintain. We’ve just included this detail to show some of the attributes of our sample 5G network.

5G also required some new templates, especially for core infrastructure that can house dozens of VNFs, 5G reference points and apps (eg games servers, CDN, etc) that you don’t want to recreate each time.

The 5G System architecture includes the following network functions (VNFs) and others.

  • Authentication Server Function (AUSF).
  • Access and Mobility Management Function (AMF).
  • Data Network (DN), e.g. operator services, Internet access or 3rd party services.
  • Unstructured Data Storage Function (UDSF).
  • Network Exposure Function (NEF).
  • Network Repository Function (NRF).
  • Network Slice Specific Authentication and Authorization Function (NSSAAF).
  • Network Slice Selection Function (NSSF).
  • Policy Control Function (PCF).
  • Session Management Function (SMF).
  • Unified Data Management (UDM).
  • Unified Data Repository (UDR).
  • User Plane Function (UPF).
  • UE radio Capability Management Function (UCMF).
  • Application Function (AF).
  • User Equipment (UE).
  • (Radio) Access Network ((R)AN).
  • 5G-Equipment Identity Register (5G-EIR).
  • Network Data Analytics Function (NWDAF).
  • CHarging Function (CHF).

Device Instances

We then create the devices to build the prototype network model shown in the first diagram above. This includes:

  • Hosting infrastructure
  • NFVI / VIM (NFV Infrastructure and Virtualised Infrastructure Management)
  • A 5GCN (5G Core Network)
  • An IMS (IP Multimedia Subsystem)
  • An RIC (RAN Intelligent Controller)
  • Virtualised Network Functions (AUSF, AMF, NRF, CU, DU, etc)
  • Mobile Edge Compute (MEC)
  • MEC Applications like gaming servers, CDN (Content Delivery Networks)
  • Radio Access Network (RAN) and Remote Radio Units (RRU)

This diagram below shows a small snapshot of the 5G Core. The templates we created earlier sure came in handy to avoid re-creating these hierarchies for each device type:

Note that the VirtualPorts are used for 5G reference points to support logical links, which we’ll cover later.

The diagrams below show the rack-layout views of core and edge hosting respectively. You’ll notice the hierarchy of device, NFVI, VNF-group, VNFs and applications are shown:

Physical Connections

To create the physical connectivity between core, edge and RRU, we’ve re-used the fibre cables, splice joints and ODFs that we demonstrated in the introduction to the OSS Sandpit inventory module.

In this case, we’ve just used fibres that were spare from last time and patched onto the 5G network’s physical infrastructure. The diagram below shows the physical path all the way from the Data Network (DN – aka a core router) to the transmitting antenna at site 2040.

This diagram includes router, core hosting, ODFs (optical patch panels), cables, splice joints, edge hosting, Radio Units and antenna, as well as fibre front and backhaul circuits.

Logical Connections

We also decided to create the various logical connections – in the most part these are interfaces between VNFs – via the standardised 5G Reference Points. 

You can also find a reference to the various logical interfaces / reference-points in the top-right corner of the prototype diagram (first diagram above).

You can also see the full list of reference points from any given VNF, as shown in the example of the AMF below. You’ll notice that these have already been set up as logical links to other components, as shown under “mplsLink” in the bottom pane. (ie the top pane are the “ports” on the AMF, the bottom pane shows the logical links to other VNFs)

The upper pane shows the instance of AMF (on the core) and its various interface points (A-end of the interface as VirtualPorts). The lower pane shows the relationships to Z-end components via logical circuits (note that I had to model them as MPLS links, which is not quite right, but the workaround needed in the tool).

You’ll also notice that the AMF is used by a number of network slices (under “uses” in the bottom pane), but we’ll get to that next.

Network Slices

Whilst not really technically correct, we’ve simulated some network slices in the form of “internal” services. To simplify, for each network slice type we’ve created a separate service terminating at each RRU. So, we’ve associated each RRU, Mobile Edge Infra (RAN), AMF (the Access and Mobility Management Function within the core) and the NSSF (the Network Slice Selection Function within the core) to these network slice “services.”

Some samples are shown below.

BTW 3GPP has defined the following Slice Types:

  • MIoT – Massive Internet of Things – support a huge device counts with enhanced coverage and low power usage
  • URLLC –  Ultra-Reliable Low-Latency Communications – to support low-latency, mission-critical applications
  • eMBB – Enhanced Mobile Broadband – to provide high speed data for application use (eg video conferencing, etc) and
  • V2X – Vehicle to Everything

Service Impact Analysis (SIA)

We can also use the service relationships to determine which Network Slices would be affected if the AMF failed. In the example below, there would be seven slices affected (see under “Uses” in the bottom pane), including all supported via sites 2040 and 2052

Similar analysis could be done using the getAffectedServices API that we demonstrated in the OSS Sandpit Inventory Intro post.

SigScale RIM

Over the last few weeks, I’ve also been using another open-source inventory management tool from SigScale called RIM (a Resource Inventory Manager designed to support service assurance use cases). It shines a light on mobile networks in particular.

The project creators authored the TM Forum best practice document IG1217 Resource Inventory of 3GPP NRM for Service Assurance which details the rationale for, and process of, mapping 3GPP information models to TM Forum’s TMF634 (Resource Catalog Mgmt) and TMF639 (Resource Inventory Mgmt) standards.

I plan to also use RIM’s REST interface (based on TM Forum’s OpenAPIs) to share data both ways with the Kuwaiba inventory module in the future. 

Summary

I hope you enjoyed this brief introduction into how we’ve modelled a sample 5G network into the Inventory module of our Personal OSS Sandpit Project. Click on the link to step back to the parent page and see what other modules and/or use-cases are available for review.

If you think there are better ways of modelling the 5G network, if I’ve missed some of the nuances or practicalities, I’d love to hear your feedback. Leave us a note in the contact form below.

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