Sunday, August 5, 2012

Demystifying SDN for Carrier Ethernet Networks

by Sandy Orlando,  

Software Defined Networking (SDN) is the hottest new technology in networking. Google is running its backbone network traffic on an SDN network built using OpenFlow. Nicira was acquired by VMware for $1.26 billion to accelerate the adoption of network virtualization in the data center. Yet with all the buzz about SDN, it is not clear how it will be deployed in service provider networks and what it means to the expansion of Carrier Ethernet. 

Tsunami of data driving change

SDN and Carrier Ethernet are not mutually exclusive technologies. What’s more, both technologies help address the growing tsunami of data driven by the growth in mobile phones and tablets, the emergence of BIG DATA, and the rise in machine-to-machine communications.
Not only is the amount of data exploding, but the characteristics of that traffic are changing with over 70 percent of network traffic on mobile networks streaming media. As service providers roll-out new network services, they struggle with how to keep pace with growing consumer and business demand and how to grow their Average Revenue per User (ARPU) faster than costs. The growing appetite for new services as well as the pace of rolling out new services every three to six months is straining service provider networks.

In comes Carrier Ethernet and SDN

There is no secret why Carrier Ethernet is a $25 billion dollar business, expected to grow to over $47 billion by 2015. Carrier Ethernet offers significant cost advantages for service providers providing WAN transport for a wide-range of services, including mobile backhaul. With Carrier Ethernet, service providers can provide high-value-per-bit at a lower-cost-per-bit while maintaining the reliability and predictable performance required by even the most latency-sensitive applications.

The next stage of Carrier Ethernet growth will come from cloud services and Carrier Ethernet interconnects, combined with virtualized network services. The cost advantages of Ethernet alone cannot keep pace with the uncontrollable demand for bandwidth combined with the emergence of on-demand network services. The next generation of Carrier Ethernet solutions will need a new approach to network equipment design and architecture provided by SDN.

SDN fundamentals

Software Defined Networking is a new approach to architecting networking equipment that fundamentally changes the way we design and build networks in a data center and over a wide-area network (WAN). SDN moves from the monolithic network equipment design based on custom silicon, a custom control plane, and tightly integrated network applications (services) to a modular, programmable, and distributed design (figure 1).

Figure 1: Network architecture transformation.
The key to SDN is the decoupling of network control from traffic forwarding. This migration to a separate software-based controller offers a number of key advantages:
  • Programmability
  • Network application (service) abstraction
  • Global network view
Whether these controllers are based on the emerging OpenFlow standard or a hybrid of legacy switching/routing alongside OpenFlow, the network intelligence is centralized and appears to applications and policy engines as a single logical switch, which simplifies network design and operations.

Distributed traffic forwarders can be added as demand dictates, reducing costly oversubscription of network bandwidth. Moreover, the separation of the network services enables service providers to more quickly add new services without having to forklift networking devices.

The role of OpenFlow

OpenFlow is a communications interface between the control and forwarding layers in an SDN architecture. It allows direct access to and manipulation of the forwarding plane of physical and virtual network devices. The OpenFlow standard is developed by the Open Networking Foundation which was launched in 2011 by Duetsche Telecom, Facebook, Google, Microsoft, Verizon, and Yahoo.

The current version of OpenFlow (version 1.3) provides an instruction set for networks analogous to the x86 instruction set for PCs. The Open Flow (figure 2) protocol includes flow tables (generic primitives) that sit on top of (virtual) switch Ternary Content Addressable Memory (TCAM) and can perform the following actions:
  • Switching and routing
  • Firewalling
  • Switching non-OpenFlow logic locally
  • Sending to controller for processing

Figure 2: OpenFlow, courtesy of Open Networking Foundation, 2012

Other SDN standards and research

In addition to OpenFlow, there are several other standards and research activities for SDN, including:
  • Open Networking Foundation: Hybrid programmable forwarding planes
  • ITEF:
    • MPLS-TP Pseudowire configuration using OpenFlow 1.3 (draft-medved-pwe3-of-config-00)
    • SDNi: A Message Exchange Protocol for Software Defined Networks (SDNS) across Multiple Domains (draft-yin-sdn-sdni-00.txt)
    • Use Cases for ALTO with Software Defined Networks (draft-xie-alto-sdn-use-cases-01.txt)
  • MEF: is working on cloud-computing and SDN standards
See the ONF and IETF websites for full list of SDN standards.

SDN is important for the future of Carrier Ethernet

Software Defined Networking is important for the evolution of Carrier Ethernet. It provides a new mechanism for architecting networking equipment and network designs. Moreover, implementing SDN does not necessarily require a rip and replace strategy. Service providers and network equipment vendors can begin identifying the high-value use cases to take advantage of the flexibility and programmability of SDN. These can include:

  • Dynamically partitioning access points and cell radios on demand based on a number of different parameters, including carrier, usage, identity, device type at the mobile edge, enabling optimal use of spectrum, Wi-Fi, and Carrier Ethernet mobile backhaul links.
  • Pooled compute and storage across geographically distributed data centers, connected with Carrier Ethernet transport using SDN, which will carve out bandwidth and allocate optimal use of bandwidth.
  • Traffic steering for content management and distribution, providing granular routing of traffic based on a wide-range of parameters such as subscriber policy, application type, and cache asset.

Waves of adoption

SDN is in its infancy and we have seen the first waves of adoption washing over the data center. For service providers and Carrier Ethernet equipment manufacturers, now is the time to begin researching SDN and identifying use cases that will drive future business.

While the ITEF and the MEF are beginning to explore SDN, the best place to learn about the technology is the Open Networking Foundation: The ONF is the standards body for SDN and OpenFlow, and has tutorials and the OpenFlow specifications. In addition, the proceedings from the Open Networking Summit from April 2012 are online at There are a number sessions from service providers and vendors on SDN for carrier networks.

As the tsunami of data grows, the emergence of SDN in carrier networks is inevitable. Only a fundamental change in how we architect networks can prepare us for the dynamic growth in communications in the coming decades. Carrier Ethernet will continue to grow. As network equipment providers adopt SDN architectures, service providers will see more opportunities to accelerate new and profitable network services.

About the Author

Sandy Orlando is a high-tech marketing executive with extensive experience in developing winning business strategies for networking and virtualization companies. She transformed the marketing strategy for IP Infusion, moving it from a point protocol provider to the leader in SDN embedded networking platforms. She has written about trends in carrier and enterprise networking and has spoken at data center and Ethernet conferences regarding the network transition to SDN.

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