This document discusses network function virtualization (NFV) and virtual network functions (VNFs). It covers the overview of VNF architecture in the NFV framework, including VNF design patterns, properties, lifecycle, and fault management. VNFs are software implementations of network functions that run over NFV infrastructure and are orchestrated by NFV orchestrators and VNF managers. A VNF consists of one or more VNF components that have well-defined interfaces and can be deployed, managed, and upgraded independently. The document describes the various states, interfaces, and descriptors involved in the lifecycle of VNF instantiation, scaling, updating and upgrading.

1. Network Function Virtualisation -
VNF Architecture
Neelima Sharma

2. The content of this presentation is taken from the ETSI
NFV specifications and from various presentations
available on internet

3. What is covered…
 Overview of VNF in NFV framework
 VNF Design Patterns and Properties
 VNF LifeCycle
 VNF Fault Management

4. Virtual Network Functions - Overview
 Software implementation of the legacy network functions
 Network Function capable of running over NFVI
 Network Function orchestrated by NFVO and VNF Manager
 VNF may be implemented as single network entity as per standards
 VNF may be implemented as group of network entities
 VNF provider structure the software into software components called
as VNF Components (VNFC)
 VNF’s are implemented with one or more VNFC
 VNF instance map 1:1 to NFVI virtualized container interface as
shown in the below slide
 VNF instance is the runtime instantiation of the VNF which consist of
VNFC instance (VNFCI)
 Requirements for the initial deployment are defined in VNF descriptor
(VNFD)
 A VNF can generally be assumed to be packaged by a single VNF
provider

5. Virtual Network Functions – Functional View
Below figure illustrates the functional view of VNF

6. Virtual Network Functions – Interfaces
 Interface is a point of interaction between two entities
 ESTI refers interfaces as reference point
 There are 5 interfaces as shown the figures
 SWA-1
 Interface for communication between two VNF’s
 Connect various VNF in a forwarding graph
 Represent data/control plane interfaces of the NF (VNF,PNF)
 VNF may support one or more VNF
 SWA-2
 Interface internal to the VNF for communication between VNFC
 Vendor specific
 Logical interface which makes use network connectivity services available at
SWA-5 interface
 SWA-3 : Interface for communication between VNF and VNF Manager
 SWA-4 : Interface for communication between VNF and EMS
 SWA-5 : Interface for communication between VNF and NFVI

7. Virtual Network Functions – Interfaces
 There are 5 interfaces as shown the figures
 SWA-3
 Interface for communication between VNF and VNF Manager
 Management interface to perform the life cycle management of VNF
 Interconnection attributes like for IP/L2 connectivity
 SWA-4
 Interface for communication between VNF and EMS
 Runtime management of VNF according to the fulfilment, assurance and billing
FAB and FCAPS
 SWA-5
 Interface for communication between VNF and NFVI container
 Provide virtualized slice of NFVI resources allocated to the VNF
 It has sub-interfaces to perform specific set of uses, roles and type of inter-connection
attribute

8. Virtual Network Functions – Interfaces

9. Virtual Network Functions – Interfaces

10. Virtual Network Functions – Design and Properties
This slides further are divided further as
 Internal structure
 Life Cycle
 VNFC states
 Load Balancing

11. Virtual Network Functions – Internal Structure

12. Virtual Network Functions - Instantiation
There are two ways to achieve this
 Parallelizable
 Instantiation multiple time per VNF instance but with constraints on the number
 Non-Parallelizable
 Instantiation once per VNF instance

13. Virtual Network Functions - States
 StateFul VNFC
 VNFC that needs to handles state information of the VNF
 VNFC can be implemented stateless by storing the state in the external
repository to VNFC
 Stateless VNFC
 VNFC that does not need to handle the state information

14. Virtual Network Functions – Load Balancer
 VNF - Internal Load Balancer
 1 VNF instance seen as 1 logical NFV by peer NF
 VNF has atleast one VNFC which can be replicated
 Internal load balancer VNFC which scatters/collects
information/packets/flows/session to/from the different VNFCI
 VNF – External Load Balancer
 N VNF instance seen as 1 logical NFV by peer NF
 External load balancer which will be another VNF
which scatters/collects information/packets/flows
/session to/from the different VNF instances

15. Virtual Network Functions – Load Balancer
 End-to-End Load Balancing
 N VNF instance seen as N logical NFV by peer NF
 Peer NF itself contains load balancing functionality
 If VNFs contains the state information then the LB NF shall direct flows to the
VNF instance that has the appropriate configured/learned state.
 Infrastructure Load Balancer

16. Virtual Network Functions – VNF Scaling
 Auto Scaling
 VNF manager triggers the scaling based on rules in VNFD
 Both scale out/in and scale down/up may be supported
 On demand Scaling
 VNF contains resource controller functionality to monitor KPI and trigger the
scaling of VNFs
 Both scale out/in and scale down/up may be supported
 Scaling based on management request
 Manually triggered scaling
 OSS/BSS triggered scaling based on rules in VNFD via NFVO

17. Virtual Network Functions – VNF Update and Upgrade
 VNF Update
 Does not introduce new functionality and/or new interfaces
 Methods for updating can differ from vendor to vendor
 Automatic procedure to start the update which is controllable and perform the
roll-back on failure
 VNF Upgrade
 Might introduce new functionality and/or new interfaces
 Methods for updating can differ from vendor to vendor
 Automatic procedure to start the update which is controllable and perform the
roll-back on failure

18. Virtual Network Functions – VNF Properties
 Hardware Independence
 COTS-Ready
 Partly COTS-Ready
 Hardware dependent
 Virtualization and Container Awareness
 Hypervisor agnostic
 Hypervisor dependent
 Operating system containers
 Higher layer container technologies
 Not virtualized and no container technology
 Partly virtualized

19. Virtual Network Functions – VNF Properties
 Elasticity
 No elasticity
 Elasticity by scaling up/down only
 Elasticity by scaling in/out only
 Elasticity in either dimension
 VNF Policy Management
 Fully policy based VNF
 Not policy based VNF
 Migration Operations
 No live migration supported
 Live migration supported
 Migration partially supported
 Other migration mechanisms

20. Virtual Network Functions – VNF Description (VNFD)
 Definition :
“The template captures the general characteristics of each VNF and is used to on-board
the VNF, in order to support on demand instantiation of the VNF’s in an operator’s
network. “
 VNFD Composition
 VNF identification data
 Data to uniquely identify the VNF vendor/provider
 Type and description of the VNF
 Version
 VNF specific data
 Specific VNF configuration data
 Connectivity requirements and inter-dependencies of VNFCs
 VNF lifecycle workflow scripts
 Deployment flavours

21. Virtual Network Functions – VNF Description (VNFD)
 VNFC Data
 VNF identification data
 Type and identification
 Specific VNFC configuration data and scripts.
 Deployment constraints
 Virtual container files/images references
 VNFC binaries plus operating system
 Empty operating system, and/or
 Empty virtual container (i.e., unloaded operating system)
 Virtualized Resource requirements
 Compute Resources
 Storage Resources
 Network Resources

22. Virtual Network Functions – VNF Life Cycle

23. Virtual Network Functions – VNF Instantiation Process

24. Virtual Network Functions – VNF Instantiation Process
VNFD Details

25. Virtual Network Functions – VNF Fault Management
 VNF fault management includes
 Fault Detection
 Fault localization
 Fault reporting
 Faults involving the virtualized resources allocated and consumed by VNF
 Faults within a VNF
 Virtualized Resource Faults
 Fault in virtualized resources that might affect a VNF’s proper functioning
 Fault in the VNF’s redundancy scheme
 Fault in the Vn-nf/SWA-5 interface
 Faults concerning the virtualization container connectivity

26. Virtual Network Functions – VNF Fault Management
 VNF Faults
 Software bug related faults
 Communication failures among VNFC’s
 Security faults
 VNF configuration failures

27. THANK YOU !!!!