Sunday, June 21, 2015

Blueprint: 5G and the Need For SDN Flow Optimization

by Scott Sumner, VP Solutions Development and Marketing, Accedian Networks

As more subscribers run bandwidth-intensive applications from a variety of devices, mobile access networks are increasingly strained to maintain quality. According to Ericsson, annual mobile traffic throughput is predicted to increase from 58 exabytes in 2013 to roughly 335 exabytes by 2020. It’s clear that brute-force bandwidth over-provisioning is no longer an economically feasible solution.

What strategies can operators implement to meet growing quality of experience (QoE) expectations, especially in the face of finite spectrum?

Part of the answer is improvements to 4G networks using technologies like LTE-A, LTE unlicensed, and voice over LTE (VoLTE). Just in the mobile space alone, Groupe Speciale Mobile Association (GSMA) expects that 4G networks—as fast as they can be deployed—will reach their limits within five years, making this option a stopgap method and a stepping stone on the way to bigger and better things.

5G networks and standards are the inevitable answer, taking bandwidth another order of magnitude forward, supporting 1000% device densification and the seamless coexistence of the Internet of Things (IoT). Getting there requires understanding the real-world dynamics at play, the role of Software Defined Networking (SDN) in 5G, and requirements for performance assurance in a virtualized world.

5G Visions and Realities

As it is now envisioned, 5G will come with further tightening of performance requirements, approaching sub-millisecond latency bounds, minimal packet loss, and higher availability limits approaching 99.95%. These sound great in theory, but in the real world are challenging to achieve.

Complicating planning and development efforts is the fact that 5G proposals like those published recently by GSMA and NGMN focus on multiple end use cases or applications, each with quite different performance demands on the network: some high bandwidth, some low latency, some both, some neither. These competing applications necessitate exceptional quality of service (QoS), meeting the diverse requirements of each service, while maintaining the most efficient use of precious capacity and infrastructure.

Together, all of this requires a new approach to networking and performance assurance.

SDN’s Role in 5G

It’s generally agreed on that SDN is implicit to 5G. SDN separates control and data planes, allowing multiple frequency bands (such as millimeter wave combined with 4G spectrum) to be implemented without requiring changes to the control infrastructure. It also enables the sophisticated traffic delivery over multiple backhaul paths involved in coordinated multipoint (CoMP) arrangements, where multiple carriers simultaneously link to the same user equipment (UE).

SDN control enables spin-up of virtual networks that address each application specifically—including the virtual network functions (VNFs) chained together to deliver the service. The coexistence of these application-specific virtual networks, along with path decisions based on their performance requirements, are unique “layers” in the network, summed up in the NGMN-coined term “network slicing.”


Performance must be assured between chained VNFs, as well as
between endpoints relying on ultra-low latency interaction.

However, the SDN controllers required to support multi-carrier aggregation, dynamic traffic engineering, and performance optimization require a real-time feed of network performance to optimize QoE. Without this visibility, traffic may be sent over routes with the fewest hops, not those with the lowest latency, for example. Optimizing performance for critical applications also means lower-priority services should use less-desired routes, to free up capacity. Performance optimization applications and self-organizing networks (SONs), therefore, require immediate, continuous visibility into the ‘network state.’

Performance Assurance in a Virtualized World

In a multi-slice, multi-application network that is continuously tuned by SDN and application optimization controllers, a real-time performance view—of Layer 2 and 3 metrics such as utilization, capacity, packet loss, and latency; and QoE metrics like VoLTE MOS—must cover every link and service to provide adequate performance feedback.


Optimal multi-path backhaul pathing relies on tight coordination between SDN controllers and an instrumentation layer.

To achieve this ‘instrumentation layer’ over all slices and sections of their network, operators can build on the performance monitoring capabilities and standards already supported by their network infrastructure, supplementing with cost-efficient virtualized test points.

Specific requirements for this level of network performance assurance include:

Performance assurance attributes characterized as real-time, adaptive, directional, ubiquitous, embedded, and open/standards-based with microsecond (┬Ás) precise delay metrics—ensuring that ultra-tight synchronization and control signaling are delivered as required.

Monitoring metrics covering per-flow bandwidth utilization, available capacity, packet loss, latency, delay variation, and QoS/QoE KPIs for VoLTE and applications.

Network visibility that’s ubiquitous, covering all locations and layers, with “resolution on demand” to avoid drowning in the data lake of big analytics.

Affordable technology is now available to help operators gain this needed network visibility. For example, advances in NFV-based instrumentation replicate the full functionality of dedicated test sets. Powerful test probes in smart SFPs and miniaturized modules allow full network performance assurance coverage at savings up to 90% compared with legacy methods.

Using network-embedded instrumentation, LTE-A networks can approach 5G performance with proper optimization:

1. Assess network readiness for incremental capacity and service upgrades.
2. Localize performance pinch points to focus upgrades and optimization efforts.
3. Monitor utilization trends and variation, and tune the network with real-time feedback to get the most out of existing infrastructure.
4. Monitor performance over the migration phase to NFV / SDN for troubleshooting and to optimize network configuration as traffic load increases.

The path to 5G relies on optimizing latency and increasing network capacity, while allowing the assured coexistence of applications as diverse as the Internet of Things (IoT), security, streaming 8K video, and multi-caller VoLTE sessions. SDN flow optimization is the foundation needed to meet those requirements. Visibility into the network state is the first step. Operators can deploy this today and pave an assured path to the higher-capacity networks of tomorrow.

About the Author

Scott Sumner is VP of solutions marketing at Accedian Networks. He has extensive experience in wireless, Carrier Ethernet and service assurance, with over 15 years of experience including roles as GM of Performant Networks, Director of Program Management & Engineering at MPB Communications, VP of Marketing at Minacom (Tektronix), and Aethera Networks (Positron / Marconi), Partnership and M&A Program Manager at EXFO, as well as project and engineering management roles at PerkinElmer Optoelectronics (EG&G).   He has Masters and Bachelor degrees in Engineering (M.Eng, B.Eng) from McGill University in Montreal, Canada, and completed professional business management training at the John Molson School of Business, the Alliance Institute, and the Project Management Institute.

About Accedian Networks 

Accedian Networks is the Performance Assurance Solution Specialist for mobile networks and enterprise ­ to­ data center connectivity. Open, multi­vendor interoperable and programmable solutions go beyond standard ­based performance assurance to deliver Network State+™, the most complete view of network health. Automated service activation testing and real­ time performance monitoring feature unrivalled precision and granularity, while H­QoS traffic conditioning optimizes service performance. Since 2005, Accedian has delivered platforms assuring hundreds of thousands of cell sites globally.www.Accedian.com


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