Cloud Computing

Network and Cloud: SDN and NFV 101

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At last year’s Mobile World Congress, AT&T outlined their plans for their network of the future: the ‘User-Defined Network Cloud’.

AT&T and others are basically starting to apply Cloud to the Communications Network.  The motivation is simply to reduce cost and increase flexibility of the network.

The underlying capabilities being used to apply Cloud to the Communications Network are Software Defined Networking (SDN) and Network Function Virtualisation (NFV).  SDN and NFV are developments in network communications that appear likely to introduce transformative change to the communications industry worldwide.

For the time poor or those suffering an attention deficit, here’s my succinct outline of SDN and NFV:

  • Basically SDN and NFV use advances in the Cloud architectures of IT to split communications hardware from software, breaking the traditional network equipment architectural model where network function is implemented as an appliance comprising both hardware and software from one vendor
  • Instead of a single network appliance, with SDN and NFV the switching hardware is commoditised and the network software is separated, virtualised and deployed in a Cloud, thereby decreasing costs and making network function faster and easier to deploy and dynamically modify and scale

And for those who want to go to the next level of detail, or are simply very bored while stuck in an airport lounge, here’s the key points on SDN background, standards and architecture:

  • SDN is an innovation in how Internet Protocol (IP) networks are designed and implemented.  SDN was invented at Stanford University and the University of California, Berkeley and has been embraced by the market as an alternative to traditional routers implemented as appliances
  • The Open Networking Foundation (ONF) is standardizing SDN with OpenFlow being the ONF communications protocol between the control and data planes.  SDN is a key component of public cloud infrastructure: Google’s B4 network, which links its global data centres, has been based on SDN since 2011.  There are now open source SDN projects like OpenDaylight from the Linux Foundation.  IBM is one of the founding members of OpenDaylight
  • There are two architectural models for SDN: Overlay, where the SDN is deployed on top of the existing IP network and Openflow, or Native, where the SDN displaces the existing IP network.  In an Openflow SDN, router appliances are replaced with Layer 2 data forwarding switches and network control software (such as open source OpenDaylight) which access the Layer 2 switches using the OpenFlow communications protocol.

In other words, Overlay SDN sits on top of the existing IP network while Openflow SDN is a simplified replacement.

While SDN applies to IP Networks, NFV is relevant to the telco networks:

  • Network Function Virtualization (NFV) is an innovation in how telecom equipment is implemented.  Telecom equipment is the basis for the communications networks such as the cellular networks used by Communications Service Providers
  • Like SDN, NFV separates networking hardware from software, enabling hardware to be commoditised and software to be virtualised and sourced from multiple parties.  NFV function includes Service Provider network function such as Enhanced Packet Core for mobile networks.  One use case for a virtual EPC is to provide a separate packet core for every enterprise customer, critical for Machine to Machine applications.
  • SDN with NFV also enables Communications Service Providers to more easily provide revenue generating services to the business and government market.  Examples include Customer Premise function such as firewalls, Network Address Translation and voice services, deployed on a Cloud in the Service Provider Environment rather than in the customer premise.  Communications Service Providers that do a good job of blending Compute, Storage and Application Cloud services with Network Cloud and device services in a single commercial bundle are likely to have a compelling advantage over Cloud providers offering only a single class of service.
  • NFV is an initiative started by the major fixed and mobile Communications Service Providers, including AT&T, BT, Deutsche Telekom, NTT and Telefonica.  ETSI is standardizing NFV and has just published the first set of NFV specifications.  OPNFV is the Open Source project created by looking to accelerate NFV by implementing key NFV components.  IBM is a Platinum member of OPNFV, drawing on 14 years of experience with Linux and the Open Source community.  NFV is causing disruption to the telecom supply chain including both telecom equipment manufacturers and network equipment providers.  Start-ups basing their offerings on open source are providing valuable new options to Communications Service Providers.

And, the big questions is what is industry actually doing with cloud and the network?

Despite the obvious risks associated with making sweeping generalisations, let me make the following observations:

  • Economics is driving many tier one Communications Service Providers to investigate SDN and NFV: the increasing volume of internet traffic in turn increases the capacity requirements and capital and operational cost of the current networks, while at the same time competition is driving down price.  SDN and NFV offer a lower cost alternative to current networks.
  • Many tier one Communications Service Providers are exploring SDN and NFV using interoperable Cloud, SDN and NFV capabilities from multiple existing vendors and start-ups today in order to test capabilities, evolve their target architectures and establish firm plans to significantly reduce cost of their traditional fixed and mobile networks.  This activity is further dissolving organisational boundaries between Network and IT
  • Tier 2 Communications Service Providers appear to be running tactical trials of vendor-specific capabilities, without necessary developing or progressing plans to evolve the network
  • A secondary but still important motivation for all Communications Service Providers is to increase service innovation including faster time to market and new services such as Virtual CPE
  • Enterprises are starting to use SDN, primarily in their data centres. The tactical starting point is often simply replacing racks of traditional router appliances with virtual routers running on commodity x86 hardware. Even where Enterprises are continuing to buy appliances, many requiring the vendor to also supply the equivalent function in virtual form. IBM’s research indicates there is a significant cost reduction in data centre operation when using SDN.

This year’s Mobile World Congress is only a few weeks away.  There’s several sessions on network evolution and cloud in the conference program and there will be demonstrations from IBM and others in the Exhibitor Zone.  I’m looking forward to hearing how real world SDN and NFV implementations are progressing.

Acknowledgements: the author would like to thank his colleague Zygmunt Lozinski for invaluable input.


Client Technical Advisor to Telecom & Media

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