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Remedy throughput bottleneck

01 Mar 2011

Squeezing the last potential drop of performance from a costly Wide Area Network (WAN) or internet connection is usually pretty high up on the list of goals for the average CIO or IT Manager. Network performance is usually one of the first things that business users or customers notice. It may be staff accessing a company internet or website, or branch offices accessing Sharepoint sites at a head office or central data centre. It may even be a large-scale e-commerce site serving hundreds of thousands of end users.

It’s important to consider carefully the exact problem that needs to be addressed. In each of the scenarios above, a different solution is

likely to reap the most benefit. WAN optimisation, Content Delivery Networks (CDNs) and simple changes in access capacity or network services are all ways of improving network performance, that meet different technical and business needs.

WAN optimisation is typically deployed in a point-to-point or multi-site configuration. A physical device is deployed at each site which uses a variety of techniques to improve the performance of applications being run over the network. It’s generally suited to:

  • Sites where WAN access is expensive or constricted.
  • Private networks in a point-to-point or hub and spoke topology.
  • Improving performance of "business” applications – services such as Citrix, SAP and many distributed storage protocols and web-based applications.

Generally, WAN optimisation platforms won’t speed access to general internet services; many platforms offer some form of web caching capability which can help performance. However, they are generally far more suited to improving the performance of specific applications operating within a closed, controlled network environment.

Content Delivery Networks (CDNs) solve a different problem. CDNs are fast becoming ubiquitous in today’s internet. The chances are high that you access content delivered via a CDN every time you browse the web. Google, YouTube, Microsoft Updates, Apple iTunes, and many large news and media organisations all use global CDNs to make their content available to as many users as quickly, efficiently and as cost-effectively as possible.

The CDN market globally is dominated by a handful of players – Akamai Networks, Limelight Networks, and Edgecast are all examples – and Akamai in particular has a strong presence in New Zealand. There is significant value to be found by utilising local CDNs that focus on building a highly capable and extensive infrastructure within a specific geographic region, such as New Zealand. Our nation is characterised by its extreme isolation from the rest of the world and the enormous cost of delivery of high-bandwidth content.

CDNs are there to serve end-users. For businesses, they mean one thing: their customers can reach their online products faster, more effectively and often at a cheaper price. CDNs are particularly well suited to:

  • Serving a wide geographic distribution of end users
  • Serving high capacity or premium content that can’t be compressed at the network level, e.g. video and audio.
  • Serving sporadic bursts of traffic, where peaks in demand are infrequent but usually considerably higher than average.
  • Cases where access networks are cheap and backhaul and transit networks are expensive.
  • A "pay-as-you-go” rather than fixed-capital-cost model.

Orcon has recently deployed a national CDN, initially to service the recently-launched iSky online video portal. The application is ideally suited to a CDN as it fits many of the criteria mentioned above. The content is high-bandwidth, already compressed and needs to reach a very wide geographic distribution of customers at as high a level of quality as possible. While iSky is the first major application that uses the CDN, it has applications for a wide range of business needs. Any large-scale "cloud” service which also relies on high-quality distribution of large content files to a large customer base can benefit from such a service.

In some cases, the best solution is simply to add capacity. Metro Ethernet in CBD areas is becoming more affordable and over time the UFB is likely to improve both reach and cost. While there is a big jump in cost from a basic best-effort business ADSL retail service, once the leap to larger-capacity dedicated data services such as S.HDSL or Metro Ethernet has been made, incremental improvements in speed are usually relatively cheap.

A 100Mb fibre-base Metro Ethernet access for example, is usually less than twice the cost of a 10Mb service and offers 10 times the capacity. Service providers usually offer a graduated (and more affordable) growth path for those who don’t need to grow capacity quite that quickly. If a business is fortunate enough to be located in the coverage area of a regional fibre operator (such as Citylink in Wellington, Enable in Christchurch, or Velocity in Hamilton), then 100Mb, 1000Mb, or even dark fibre services are often very affordable.

Service providers can in many cases add significant value to WAN services through hosted traffic management or Quality of Service (QoS). Rather than using compression or caching techniques, the approach manages the bandwidth available in the network and ensures it is distributed fairly, or distributed based on a set of business rules that provide priority to one service or application or another. Most service providers have the capability to identify traffic at least at the port level and apply specific policy to it from there.

In summary, when reviewing network capacity and evaluating potential solutions to throughput bottlenecks or performance problems, consider carefully your specific technical architecture and the applications and services you are operating and make sure you’re matching up with a solution that is best suited to your needs.