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