One of the industry’s latest technology buzzwords, software- defined networking (SDN) allows greater programmability to be introduced to networks of all shapes and sizes. And despite the relative youth of SDN, data center and other network operators are already pursuing a wide range of applications; these include the use of SDN to support increased network flexibility, scalability and innovation.

One of the most prolific deployments of SDN to date is Google’s. It has used the technology to improve application-deployment agility and better serve its enterprise customers.

Within the Asia Pacific (APAC) region significant SDN deployments include those of Pacnet, which unveiled a pan-Asia Network-as-a-Service (NaaS) offering in late 2013, based on the fiber backbone connecting its ten regional data centers.

Following that development, in April 2014, cloud and data center services provider OneAsia announced the deployment of SDN within its Hong Kong and Shanghai data centers to support the growing demand for cloud among enterprise customers.

Today, even more novel applications of SDN are emerging, including its use to support more efficient and innovative traffic exchange within internet peering facilities.

In November 2013, CityLink, which operates New Zealand’s internet exchange points (IXPs), revealed plans to adopt NoviFlow-supplied SDN switches within the country’s five nationwide peering points (See figure 1).

The deployment of SDN-enabled exchange switches was intended to make the internet traffic peering by the organizations using the facilities more secure, stable and predictable. There are currently 87 organizations using the Auckland Peering Exchange, the largest of the five New Zealand exchanges. They include Microsoft, Vodafone, AT&T and Akamai.

The use of SDN-enabled switches at IXPs helps to eliminate or alleviate the challenges traditionally associated with the Border Gateway Protocol (BGP), the standard protocol by which network operators exchange internet traffic. These challenges relate to both the efficiency and security of traffic exchange. In addition, the use of SDN-enabled switches at IXPs allows activities that are currently not possible with conventional traffic routing infrastructure.

The application of SDN to IXPs has given rise to a new technology category – the software-defined internet exchange (SDX). An SDX offers several benefits to users, including:

• Application-specific peering: the OpenFlow protocol underpinning SDN allows networks to customize forwarding policies based on a range of data packet headers. This means that operators can establish tailored peering arrangements that are based on the type of traffic (for example settlement-free peering for video traffic). Alternatively, they can establish peering for traffic that is being routed to a specific DNS domain name or service.

• Remote peering: the ability to remotely control peering paths means that network operators can redirect traffic over better-provisioned paths or paths with pre-determined or predictable levels of service quality. There is potential for IXP operators to charge for the additional level of control that can be offered to their members and customers.

• Quality control: SDN provides IXP operators with greater control over the peering policies that are supported by the switching architecture, allowing them to permit only those policies which meet specific security and routing policy requirements. 

• Dynamic traffic engineering: rather than having to manually monitor and rebalance traffic ratios in line with peering policy agreements, an SDX controller can be set to automatically respond to information about traffic and to rebalance traffic volumes in accordance with policy demands.

By international standards the New Zealand internet exchanges are relatively small and the impact of deploying SDN across their switching infrastructure is limited in scale.

The deployment of what has been dubbed, the world’s first SDX, however, offers an important use case for assessing the potential benefits. There are certainly opportunities to deploy SDN elsewhere, both within individual IXPs or across multiple exchanges.

IXPs are already an essential part of the internet ecosystem and they continue to grow in number and size and into new geographical regions. Some of the strongest IXP growth is occurring in emerging market regions (including APAC) where internet usage is growing and where IXP penetration is weakest (see figure 2).

As new IXPs emerge to support rising volumes of online content consumption it is likely that a growing number of exchange operators will look to SDN as way to differentiate their offering and provide more attractive peering locations for network operators.

This article first appeared in FOCUS 36. To read a digital copy of the magazine, click here.