SDN and NFV: Are they the same?

Note: This post was 1st appeared in BCS ISG Blog.

As the world progresses with unprecedented changes happening all around us, new terms/buzzwords (or abbreviations) are frequently introduced. Two such terms are SDN (or software defined networking) and NFV (or network functions virtualization), widely used within telecom, cloud and enterprise environments. Even if you are from a different field than ICT (Information and communications technology), chances are that you have heard about these terms. One of the confusions specifically associated with SDN and NFV is whether they are the same? The short answer is ‘no’. Anyway, let’s look at little closer at SDN and NFV to better understand them.

While the proper definition of NFV is available at ETSI NFV ISG (European Telecommunications Standards Institute NFV Industry Specification Group) whitepaper, the simple meaning is essentially about separating hardware from associated software in different network devices/elements. This allows for the running of different network functions (like Firewall, load balance, NAT, etc.) on cheap COTS (Commercial off-the-shelf) hardware, like switches and servers.

Going on the same viewpoint of separation, while the proper definition of SDN is available at ONF (open networking Foundation), SDN is about separating control plane from the forwarding (data) plane in a network element (ex: - router, switch, optical gear, etc.). This allows multiple forwarding planes to be controlled by a logically centralized controller or NOS (network operating system) as opposed to a single control plane (ex: - card in a router for example) and to control a single forwarding plane (ex:- line cards and back-plane) in a traditional network element (ex:- internet protocol router).

NFV creates VNFs (virtual network functions) instead of traditional PNFs (physical network functions). For example, a traditional hardware firewall (PNF) vs. virtual firewall (VNF). You need connectivity between PNFs (traditionally) or VNFs or a mix of VNFs and PNFs (in a hybrid environment) to realize an end-to-end service. This connectivity can be provided by a SDN (within a data center or between data centers). If you want to relate SDN and NFV to the ISO/OSI (International standards organization/Open systems interconnection) stack, you can think of it as bottom three layers (layer 1 to layer 3) mapped to SDN and the top four layers (layer 4 to layer 7) mapped to NFV.

Both SDN and NFV can be implemented mutually exclusive to each other. However, having them together will give better benefits to telcos (or enterprises or cloud providers) and that is why you always see SDN and NFV referred together (SDN/NFV).

If you take the broad term ‘softwarisation’, which includes SDN, NFV and cloud, it is all about different abstractions;

• NFV -> Communications abstraction
• SDN -> Network abstraction
• Cloud -> Compute abstraction 

The comparison below further explains the differences between SDN and NFV.

Parameter	NFV	SDN
Type of abstraction	Communications	Network
Key term in the abbreviation	NF virtualization	SD Networking
Architecture for	Network Elements	Network
VNF relevance	Defines VNFs	Provides connectivity between VNFs
Key focus	Services	Resources (specially network)
Optimizes	Network Functions	Network
Defined by	ETSI as a requirement	ONF as a standard

Broadband: wired or wireless?

I always had this question in my mind; wired or wireless to reach the rural.

All the fixed line Communication Service Providers (CSPs) in both developing and developed countries have started their networks form the urban areas (ex: Main Switching Unit (MSU) in Public Switched Telephone Network (PSTN)) and move to sub-urban (ex: Remote Switching Unit (RSU)) and then to rural (ex: Line Extension Unit (LEU)). For both copper and fiber, this has been the practice for the last 150 years. Even wireless CSPs have followed the same path first covering the urban, then sub-urban and then rural. Two of the most obvious reasons for this, is the demand and the affordability.

When it comes to broadband (BB), now we have 2 options wired or wireless. While there are methods to re-arrange an existing copper network by shortening the copper distance and introducing FTTN/C/B to deliver BB using ADSL2+/VDSL, the re-arrangement of wireless networks are not that feasible. To cover the green areas, the operators need to deploy new networks; copper, fiber or wireless.

As you move from the urban to rural, the population/house-hold density decreases, making the requirement of coverage large. The 2 options remain as fiber and wireless (ex: LTE). Deploying new copper is not a choice any more.

But the question is, once you reach the rural, both demand and affordability decreases, especially in developing countries. On the other side, the requirements are becoming more scattered in nature making wired networks prohibitive. Therefore the ideal choice is wireless, because of the less demand, less affordability and scattered nature.

So, the viability of FTTH is only applicable in urban/sub-urban areas where the required bandwidth is not deliverable even with the existing copper network re-arrangement as described above or the copper is outdated/degraded/old. For other areas (rural) wireless is the only viable options, especially for a developing country. Please keep in mind that the green areas will most of the time are rural.

For a case study, I'll take my own country as an example. The population of Sri Lanka, a developing country, as at March 2012 is 20.3 million (approx.) [1]. According to [2] 78% of the population lives in rural areas. If we assume a house hold has 4 people, the number of house-holds is 5 million (approx.). 78% of this is 4 Million (approx.).

But, according to countries regulator [3], as at March 2012, the number of fixed lines in Sri Lanka (including CDMA) is 3.6 million. However, we need to keep in mind that big corporates use hundreds of lines per location. Therefore, we cannot use 3.6 million for the calculation.

The point however is, 78% of the households/population are rural. To reach this we have to go with wireless. This is quite evident from the figures in [3], where the mobile penetration is 91% while the fixed line penetration is 18% (approx.). This 18% is actually the saturated figure of urban and sub-urban. But when the rural areas develop (when the demand and affordability increases) the 18% will increase as explained in my previous post. In [3], the Internet penetration is also high with mobile (if calculated, 4% approx.), whereas for fixed it's only 2%, if calculated. Obviously the BB is also will follow the same percentages.

On the other hand, the 78% includes large number of Small and Medium Enterprises (SMEs), which are the main contributors to the country’s economy. For them to grow and the country to grow, the SMEs need Information Communication Technology (ICT) facilities. So the operators and the country have a great challenge to provide them the required services. Operators need to invest cautiously making sure they get positive Return-On-Investment (ROI) at the same time increase the footprint of their service coverage.

[1] http://www.statistics.gov.lk/
[2] 202.11.2.113/SEBM/ronso/no3_4/aruna.pdf
[3] http://www.trc.gov.lk/images/docs/statis_March_2012.doc

New strategies for Telcos

The Telcos (more correctly, Communication Service Providers (CSPs)) face a severe competition and a pressure today to keep their noses above the water. They can no more sell voice and bandwidth and make that a viable business proposition. Both voice and bandwidth has become a given. Most of the customers granted that as given. Recently the United Nations (UN) has accepted Internet access as a basic human right.

CSPs over the years have built their transport networks (Core, Aggregation and Access). In developing countries, the expansion of wired access networks seems to be prohibitive with the associated cost and the demography. The incumbents specially, have started copper based access networks from the urban areas and started expanding toward the sub-urban and rural. Most of the cases we find that the  already invested infrastructure delivers Plain Old Telephone Service (POTS) services to the customer and there's a huge potential that most of them can be enabled with broadband. Even with that, the total wire based coverage will still be less than 50% of the households. As you reach the rural areas the demand is more scattered and for a developing country, the only viable option is wireless.

If the balance households are reached using wireless, and an acceptable pipe is delivered to the household or individual, just by selling voice and Internet will not make the CSP win. The Average Revenue Per User (ARPU) has saturated and CSP have to think how they can make the customer spend more. The old form of merely satisfying  their communication, information and entertainment requirements is not just enough. We have to think selling the "convenience"  to the user. One example of selling the "convenience" is the e-banking introduced by the banks. People are prepared to pay a premium to this facility as they can make all their bill payments electronically.

The CSPs need to this considering the total Information Communication Technology (ICT) ecosystem, making sure all stakeholders are benefited. Just take an example. The CSPs are good at building networks (providing the transport), but they may not be good at  producing applications to run on all three screens (computer, mobile and TV). On the other hand, the software companies can produce applications (of course after a good socioeconomic study ), but they can not build communication networks. Both CSPs and software companies can get together in a win-win arrangement to provide a service to the customer. The applications so developed need to be based on the principle of "convenience".