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 !!!!