NFV Example
NFV with Customer Premises Equipment (CPE)
Virtualized Network Function (VNF)
NFV Infrastructre (NFVI): Hardware and software required to
deploy, mange and execute VNFs
Network Function (NF): Functional building block with a well
defined interfaces and well defined functional behavior
Virtualized Network Function (VNF): Software
implementation of NF that can be deployed in a virtualized
infrastructure
Container: VNF is independent of NFVI but needs a container
software on NFVI to be able to run on different hardwares
Courtesy: Introduction to Network Function Virtualization by Prof. Raj Jain, Washington University in Saint Louis.
NFV NFV is an architecture guiding management and orchestration activities,
vs whereas a VNF is the technology providing virtual (that is, hardware-
independent) network functions such as routing or firewalling.
VNF
VNF Forwarding Graph and Network Service
Network Service (NS) holds importance in NFV as in the majority of cases,
VNFs connect with one another to create services instead of working alone. Also,
VNFs connect to create “VNF Forwarding Graphs”( VNF-FG).
Let’s assume, three VNFs need to connect to one another.
Usually, a virtualization layer (hypervisor) will abstract the hardware resources
under it enabling the VNFs to connect through virtual links. Now why they are
called virtual is because you do not see them, physical.
Now you can see multiple virtual links between the VNFs.
The virtual connectivity may be based on Layer 2
topology, for example, MEF E-Line, E-LAN or E-Tree
services.
Network Forwarding Path (NFP)
Network Forwarding Path shows the path for the actual traffic flows on the virtual links.
Let’s say that in mobile core case, there is two kinds of traffic: Control Traffic and User
Traffic.
In the following case, then, the Control traffic has further two paths and the User traffic has
just one path:
NFP1- Forwarding path for “control traffic” that needs to pass through VNF1, VNF2, and
VNF3 and uses VL2
NFP2- Forwarding path for “control traffic” that needs to pass through VNF1 and VNF3
(but not VNF2) but still uses VL2 (because of applying some policy that restricts it from
VNF2)
NFP3- Forwarding path for “user traffic” that needs to pass through VNF1 and VNF3 but
need to utilize VL3
VNF Forwarding Graph (VNF-FG)
In the above example, the
Control traffic will make one
VNF-Forwarding Graph (VNF-
FG) and the User traffic will
make another VNF-FG.
Think of forwarding paths as
subsets of the VNF-FG. That is,
one VNF-FG can have multiple
forwarding paths.
Network Service (NS)
NFV Framework Requirements
1. General: Partial or full Virtualization, Predictable performance
2. Portability: Decoupled from underlying infrastructure
3. Performance: as described and facilities to monitor
4. Elasticity: Scalable to meet SLAs. Movable to other servers.
5. Resiliency: Be able to recreate after failure.
Specified packet loss rate, calls drops, time to recover, etc.
6. Security: Role-based authorization, authentication
7. Service Continuity: Seamless or non-seamless continuity after failures or
migration
Contd…
8. Service Assurance: Time stamp and forward copies of packets for
Fault detection
9. Energy Efficiency Requirements: Should be possible to put
a subset of VNF in a power conserving sleep state
10.Transition: Coexistence with Legacy and Interoperability among
multi-vendor implementations
11.Service Models: Operators may use NFV infrastructure
operated by other operators
References
1. Introduction to Network Function Virtualization by Prof. Raj Jain, Washington University in Saint Louis.
2. Han, B., Gopalakrishnan, V., Ji, L., & Lee, S. (2015). Network function virtualization: Challenges and
opportunities for innovations. IEEE communications magazine, 53(2), 90-97.
3. Mijumbi, R., Serrat, J., Gorricho, J. L., Bouten, N., De Turck, F., & Boutaba, R. (2015). Network
function virtualization: State-of-the-art and research challenges. IEEE Communications surveys &
tutorials, 18(1), 236-262.
4. Yi, B., Wang, X., Li, K., & Huang, M. (2018). A comprehensive survey of network function
virtualization. Computer Networks, 133, 212-262.
5. https://www.vmware.com/topics/glossary/content/network-functions-virtualization-nfv.html
6. Latif, Z., Sharif, K., Li, F., Karim, M. M., Biswas, S., & Wang, Y. (2020). A comprehensive survey of
interface protocols for software defined networks. Journal of Network and Computer Applications, 156,
102563.
7. https://telcocloudbridge.com/blog/beginners-guide-to-network-service-and-vnf-forwarding-graph-in-nfv/
