Six criteria for choosing a suitable content delivery network

In many industries, attractive online experiences are the be-all and end-all. Companies have to ensure that their customers can access videos, music, software or games quickly and reliably. Depending on the load, however, this can mean a complex challenge for the providers.

Guest post The users are particularly sensitive to the performance. If the system responds too slowly, they abort streams or online purchases: According to the State of Video Streaming study by Limelight Networks, almost every second user leaves a website with a loading time of more than five seconds. Around 43 percent of the respondents even switch directly to the competition.

Steve Miller-Jones, the author of this post, is VP Edge Strategic & Solutions Architecture at Limelight Networks (Image: Limelight Networks).Steve Miller-Jones, the author of this post, is VP Edge Strategic & Solutions Architecture at Limelight Networks (Image: Limelight Networks).

Companies can take various measures to improve the online user experience. A sensible option is to work with an external content delivery network (CDN). The network consists of powerful servers that cache copies of the content to be distributed at various locations worldwide. In this way, files can be made available in a very short time and the web host can be relieved.

But not all providers deliver the same performance when playing the content. Companies should therefore keep an eye on important aspects such as sufficient cache capacity, latency, throughput, availability and range before working together.

1. Low latency

Users’ expectations have never been as high as they are today when it comes to their online experiences. They want immediate feedback – be it for streaming, online shopping or gaming – and punishable delays with high abandonment rates. To reduce latency, popular content is stored by the CDNs in multiple locations near the site visitors. Content that is not found in the local cache (cache), however, must be searched in other caches or in the Origin Storage and retrieved via the network. The response time for queries depends on many variables: Was the queried
Found object in cache? If not, how good is the quality of the connection between the PoPs and the origin storage and the peering connection of the last mile? Many CDNs have insufficient cache capacity and rely on the congested Internet for data queries. In addition, they use too many intermediate stations (hops) for the transfer to the last mile provider. All of these factors can contribute to high latency. It is important for companies to ask exactly how the CDN provider ensures low end-to-end latency.

2. Ensure high throughput even at peak times

In certain applications, the effective throughput, i.e. the
Rate of successful delivery in Mbps, largely based on the user experience. This is the case, for example, when downloading large files. The slowest connection in the transmission path is decisive for the maximum theoretical throughput. In practice, however, the effective throughput is also influenced by the network conditions, the structure of the hardware and the data traffic management systems. Each CDN provider deals with these questions differently, so companies should ask exactly how a high throughput is actually guaranteed. One criterion is whether a private network is available. This is much more flexible than infrastructures that rely on the public Internet.

3. Comprehensive security functions

A website failure due to DDoS attacks or stolen content are just two of the worst problems that companies can face in the digital world. Therefore, you should also pay attention to comprehensive security concepts when choosing your CDN partner. Cloud Security Services can provide a layered defense strategy against malicious attacks on the website and unauthorized access, without affecting the performance of the web applications or the content delivery. In order to be able to curb fast DDoS attacks across the board, CDNs need efficient detection and a powerful defense integrated in the network. In addition, a Web Application Firewall (WAF) and corresponding bot management should be integrated in the CDN to protect data from hacking attacks.

4. Availability: always and everywhere

It is not just a matter of the speed of a website: it is also crucial whether this speed is constant and the content is reliably available everywhere. Therefore, companies should ask potential CDN providers about content redundancy, connectivity redundancy, proactive monitoring, and other features that protect against unexpected and expensive outages.

5. Private instead of public

Many CDN networks still rely on public Internet connections. The downside: you have no control over unpredictable bottlenecks, loss of performance, latency or packet loss. Interim storage at the network edges only helps in part. In an emergency, these imponderables can affect the
impact availability. Companies should choose networks with a private, quality-of-service (QoS) -enabled backbone. This is the only way to ensure a secure, high-performance transfer of all content in the event of a cache miss.

6. Meaningful analyzes

A performance enhancement system brings little value to businesses if you can’t measure its impact. In addition to traffic pattern trends, detailed and usable analyzes should also provide information about user behavior, the provision of services and the systems. They should also include geodata reports for the differentiated evaluation of granular data and content usage data. When streaming live events, real-time analytics are also invaluable. It is crucial that the analysis tools also provide answers to all tailor-made queries and can be viewed flexibly – whether via a web portal or via a programming interface.

In general, a CDN provider is not just a service provider that provides capacities, but solution partners and consultants. Companies should therefore specifically check beforehand whether the relevant competencies fit their own requirements. Questions about his integration skills, successful improvements in the user experience or the optimization of processes are suitable. The available service naturally plays a special role. High costs and loss of reputation can only be avoided if the CDN partner also helps immediately in an emergency.


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