Network Function Virtualization

Virtualization

5G brought new trends.

• Virtualization.

  • Simulate a hardware platform, in software: VM’s, containers.

    • Higher portability.

    • Higher scalability.

    • More cost-effective.

• Virtualized networks

  • Logical software-based routers, switches, etc.

  • Network services are easier to deploy and manage.

  • The physical part only needs to handle packet forwarding.

Virtualized Network Functions

• VNFs.

• Network functions running in a virtual way over virtualization infrastructure.

• As they are

  • Lift and shift

• Or employing cloud-native principles.

VNF Lifecycle Management

VNFs are deployed after a service request is done, via the northbound interface.

That service request is composed of templates that consist of XML payloads and configuration parameters.

Onboarding – placing the VNF image/template and configuration, in the system’s catalogue;

• Openstack qcow2 and cmdk disk formats and config drive.

Deploying – placing the resources in the virtualization infrastructure, along with zero-day configuration (credentials, licenses, network information, etc.).

Monitoring – check the health of virtual machines regarding network status, CPU, and memory consumption.

Healing – after monitoring failure conditions exposed as Key Performance Indicators (KPIs), the system can heal the VM (restart, expand, etc.).

Updating – change the details of a virtual machine, set of virtual machines or networks that interconnect them.

Undeploy – remove a VM from the system.

Network Services

A set of chained VNFs.

VNFs are interconnected and need to communicate with each other.

• Connectivity Forwarding Graph (FG) indicates how they are connected.

  • VNFFG – VNF Forwarding GraphVNFFG – VNF Forwarding Graph.

VNFFG – VNF Forwarding Graph.

• Can also be part of the forwarding graph.

VNFs+VNFFG = Network Service.

• Is managed and orchestrated together.

• Lifecycle mgmt for VNFs.

• Management of the VNFFG and NS lifecycle mgmt is going to be orchestrated across the whole lifecycle mgmt of those VNFs that form the NS.

• The NS defines some external connection points that can be connected to the end-points, defining an end-to-end service.

• We can concatenate different NS to for an end-2-end network service.

NFV Concept summary

• No longer isolated single purspose physical network services and functions.

• A standards-based approach to manage network services, using virtualization infrastructure.

• Network services are built from VNF aggregation.

• VNFs have their own lifecycle.

• But this is managed then at the NS level.

  • And at the inter-NS level too (both require orchestration).

• There is the need for management (and orchestration) of the network services.

  • Separate from the management of the applications/services themselves.

Reference architecture

VNF Descriptor

One very important tool used by the VNF Manager (VNFM).

VNF Deployment template that specifies.

• How the VNF needs to be instantiated.

• How many VM’s the VNF has?

• How those VM’s are connected.

• What are the external connection points?

• What are the requirements of the VNF, the virtualized resources, etc.

• Contains scripts that define for VNF scaling, healing, ...

Provided by the VNF vendor.

When the VNF is onboarded, the VNFD is onboarded in the VNFM.

NS Descriptor

A template that describes how the NS is composed.

• In terms of VNF.

• The VNFFG.

• Scripts and indicators that defines what the orchestrator needs to do when certain events or indicators are received.

  • These appear during the lifecycle management of the NS.

Resource Management (Simplified)