As you know, SDN & NFV are two words that have been connected during the last two years and it is becoming more and more difficult to find articles or references in which one of these two words stands alone. So I will also contribute to this. In fact there is another acronym that should be added, which is NV (Network Virtualization).
I will dedicate the first part of the article to briefly introduce those terms, and the second to briefly talk about the adoption of these approaches, media and technologies inside Telecom Operators.
SDN, NV and NFV
SDN (Software Defined Networking) is a term that appeared around 2008 and it is still quite far for being a product itself. It is more a mechanism, a tool to interact with the network, that enables us to create products, functions, abstractions within the networking space. The philosophy of SDN is about separating the Control Plane from the Data Plane (Forwarding Plane), putting all routing «intelligence», and all functions that you want to perform in a network within this Control Plane, letting the Data Plane focus on packet forwarding. Data Plane basically forwards the traffic according to the logic defined in the Control Plane.
This separation has two main reasons. One is to get rid of the 100% network owners’ dependency on hardware vendors. Currently when an operator wants to evolve its network, basically it needs to buy new boxes. With SDN, an operator can evolve “the brain” of its network, programming the Control Plane, buying more boxes (if needed) just to increase its forwarding capacity on the Data Plane. The second reason is that networks are getting more and more complicated to manage. Protocols like BGP, that have been used for a long time, have a lot of problems like manageability or presenting rooting loops. With SDN Controllers, the way in which routing is performed can be easier and more robust.
To allow communication between the Control Plane and the Forwarding Plane, there are some protocols available.
The most relevant one, linked to the SDN evolution, is OpenFlow. The OpenFlow standardization is managed by the Open Networking Foundation (ONF), a non-profit organization dedicated to network improvement through SDN. OpenFlow controller(s) communicates with OpenFlow switches using a secure channel; the aim of this communication is to update the switch flow table, that basically contains pairs of matches and actions.
Another protocol related to this world is NETCONF. NETCONF is a protocol that allows you to modify the configuration of a network device. OpenFlow and NETCONF (promoted by vendors) approaches are quite different and somehow complementary.
NV (Network Virtualization) is about supporting multiple logical networks or supporting several network services over a physical network layer. There is a parallel with the IT concept of “server virtualization” in which there is a server hypervisor that manages all the Virtual machines running over an X86 physical server. So when talking about Network Virtualization we are referring to a physical network and a network hypervisor that manages all virtual networks created over this physical network. This network hypervisor must provide two abstractions:
- Packet abstraction: To guarantee network isolation, so every single packet within a virtual network must not interfere with other networks.
- Control abstraction: To configure and manage each virtual network there should be different and independent management layers per virtual network.
With Network Virtualization costs can be reduced specially concerning Multitenant Datacenters. Another plus for Network virtualization is vendor independence, as from the same physical network layer you can create programmable networks, virtual switches, virtual links, etc. Although Virtual networks may exist without SDN, SDN can be a mechanism to implement them in an easy way.
NFV (Network Functions Virtualization). In a Telco Operator, one can find several items of hardware equipment that provide different services like GGSNs, DPIs, Load Balancers, IMS Core, Firewalls, Routers, Session Border Controllers, etc. These services usually run into proprietary hardware boxes.
When an operator wants to increase its capacity, or add new features to its original infrastructure, in the best case it has to add a new box or replace the previous one.
As the number of users, number of different services and specially data consumption are increasing dramatically, this model is no longer affordable. Instead of keeping this model, NFV proposes using IT virtualization to be able to run these network functions over x86 general purpose servers.
After the definition of the NFV concept by the European Telecommunications Standards Institute (ETSI) in late 2012, OpenDaylight consortium was created on April 2013: «The OpenDaylight Project is a collaborative open source project that aims to accelerate adoption of Software-Defined Networking (SDN) and Network Functions Virtualization (NFV) for a more transparent approach that fosters new innovation and reduces risk» (http://www.opendaylight.org/). Most of the OpenDaylight participants are network vendors; in fact most of the main Telco providers like Ericsson, Cisco, Juniper or Huawei are active members working in different groups.
NFV, NV, and SDN are different concepts aimed at different purposes, but SDN could be the tool that helps to build virtual networks that run network virtual functions on top, and SDN can be used as a central tool to orchestrate NFV, and this is what is happening right now.
Telecom Operators’ moves
The main challenges for the adoption of NFV, SDN controllers, or Network Virtualization Infrastructure are reliability, availability, performance and security. No operator will embrace these new approaches if their perceived QoS is lower. Another major challenge is all the legacy infrastructure the operators have. For some time new architectures will need to co-exist with legacy boxes and all of this must happen without affecting customers.
Telecom operators have been very active in this world although some of them have started before others. Deutsche Telekom and Verizon were (together with Google, Facebook and Microsoft) the founding members of ONF. Most of the main operators like Vodafone, China Mobile, Telefonica or Telecom Italia are part of this organization.
Whether Operators are present in organizations and forums or not, all of them are involved in adopting some of these technologies, embracing the promise of cost saving, huge improving in time to market when launching new services, flexibility and scalability. Below I briefly comment on the public initiatives some of them are involved in:
Telefonica is deploying its program «UNICA«, the aim of which is to have virtualized more than 30% of new infrastructure by 2016. Some vendors like Huawei, Alcatel Lucent, Ericsson, NSN and NEC are collaborating in this initiative.
Telefonica has also deployed this year a trial in Brazil to carry its virtualization strategy to the home. The trial consisted of virtualizing customer premises equipment (CPE) so most functions that currently are deployed over the user equipment, can be moved to the operator’s servers and provisioned through the network. Functions that can be virtualized include IP routing, firewalling, set- top boxes functionalities, etc. This has two main advantages: one is that the amount and the complexity of the boxes will decrease, achieving some degree of cost reduction; the second is that software upgrades and maintenance is done in a much more efficient way.
AT&T launched at the end of 2013 an initiative called Domain 2.0. The aim of this «transformative initiative is to enable both internal and external, to enable AT&T network services and infrastructure to be used, provisioned, and orchestrated as is typical of cloud services in data centers». This initiative is like a roadmap that sets out the direction towards network transformation. Within the framework of this program AT&T has promised to show some deployment before the end of this year (maybe related to their SDN WAN).
Several trials and initial deployment are being carried out at a Global level and throughout its subsidiaries. For example, in Australia there is a five year network evolution program, and as part of this program Vodafone will adopt NFV in the core network. This will provide greater network agility and flexibility and will create cost efficiencies.
They completed proof of concept (PoC) trials with Alcatel-Lucent, Cisco and NEC to verify the feasibility of NFV technology. They announced plans to start with the virtualization of their EPC, having commercial services by early 2016.
At Mobile World Congress 2014, China Mobile made a demonstration of a multivendor NFV POC. Using Alcatel-Lucent’s virtualized LTE radio access network (RAN) and 2 virtual EPC, one from Huawei, and another with a multivendor approach (virtual HSS from Linker Networks, virtual MME from ALU, virtual S-GW and virtual P-GW from CISCO) connected to a virtual IMS core from ZTE.
The future is now
Having a look at the state of the art within this world, analyzing what the operators and vendors and new start-up companies are doing, we can say that the Evolved Packet Core and the IMS core are candidates to be virtualized and for sure this is something that is currently happening now in some of the operators. Virtualizing Customer Premises Equipment both for the home and for the enterprise usage is another use case that makes sense to be deployed. Launching services like VoLTE or RCS will force operators to take a virtualized approach, as the old deployment based in physical boxes is not scalable and the «elasticity» feature that comes with the concept of NFV is definitely needed.
Most of the operators are making their moves and are building their own NFV roadmap. Altran is currently accompanying its clients (both Vendors and Operators) on their journey of this Network Transformation to achieve faster and more cost-efficient service deployment.