Everything you need to know about multi-CDNs in a single overview.
Up-to-date information about the components behind a multi-CDN solution and the different providers that (can) play a part in your multi-CDN setup. These components are DNS providers (for CDN balancing), data provider (for decision making), and CDN brokers (for content delivery networks).
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This website contains everything you need to know about getting a multi-CDN solution, and what to take into consideration when selecting your partners to get performance data, CDNs, CDN balancing technology, or simply the whole package.
A multi-CDN solution is an alternative to using a single CDN from one provider. Businesses may choose to use such a solution to mitigate issues associated with using a single-provider setup, such as performance degradation and outages. Essentially, the solution is all about avoiding a single point of failure (SPOF) in your content delivery network, whilst maximising web performance.
Read more about the uses of multi-CDN in this blogpost.
Essentially, a multi-CDN setup consists out of three components:
a bunch of CDNs,
CDN balancing intelligence,
a pool of data to base the balancing decisions on.
Each of these components can be sourced separately from different providers, or in combination with each other from a single vendor. The overview on this site is dedicated to the providers of these services, and they are categorised according to the service they provide. Some may only cover one or more of the three components, whereas other providers offer a fully integrated multi-CDN solution. Which provider to choose for all depends on the business needs of a client.
We use the diagram above to illustrate the differences between providers:
CDNs and performance data providers
Performance data provider
Performance data and CDN balancing technology provider
CDN balancing technology provider
CDN balancing technology and CDN providers
Integrated multi-CDN solution provider
Naturally, multiple CDNs are needed in order to set up a multi-CDN solution. On this site we look at providers that offer at least two or more CDNs, such as CDN brokers. For more information on the single ‘mono-CDN’ providers in the market, check out CDN Overview.
In a multi-CDN setup this combination isn’t relevant as the data is used internally by CDN providers, and not offered as a service.
In the feature overviews of these providers we distinguish between the type of data that they provide. Within a multi-CDN solution, you can think of selecting based on a web user’s country (or US state) of origin, or more specifically - based on their AS. Other possible selection criteria can be the costs of your CDN (selecting the cheapest provider for each user), and the the type of content requested. We’ll dismiss the latter two for now, as these criteria are not relevant in terms of the data providers that are in the market.
Companies like Catchpoint, Deepfield, New Relic and Dynatrace are examples of performance data providers. These parties offer a wide range of synthetic and or RUM monitoring services that can be used to keep tabs on the performance of anything from application to back-end, to the CDNs.
The country or state (US) where the web user is from determines which CDN provider is chosen for their request. The best performing provider for that country will be chosen, not bearing in mind their hyper-local performance and their peering agreements with Internet Service Providers (ISPs).
The data used for country-based selection comes from synthetic monitoring: tests that are performed at local datacenters that usually have a near-perfect connectivity. Sometimes providers may provide testing units to be placed at the offices and homes of employees or users. These ‘nodes’ can also be used to perform tests, and will include the so-called last mile. Tests that include the last mile are more specific and give us a better understanding of the the end user’s web experience.
Country or US state selection is only one of more meaningful variables in terms of content delivery. We often see sub-national and sub-state differences caused by the various Internet Service Providers (ISPs) in a country. Due to the presence or absence of peering agreements between CDNs and ISPs, performance can differ immensely depending on what combination of CDN and ISP is used.
Country-based selection ignores sub-national or sub-regional nuances that in terms of content delivery, can have a big impact on the web user. Selecting on AS level, or ISP level, is another option that dives deeper than the country or state level.
Taking the ISP into consideration, AS-level selection negates issues that may arise for the presence or absence of peering agreements between CDN providers and ISPs. In short, no CDN provider is the guaranteed ‘best’ provider in a certain country or state. Incorporating nuances like the ISP in the selection process allows for more user-specific content delivery optimisation.
Examples of providers in this category are Cedexis, NS1 and Dyn. They offer both the DNS service needed to manage traffic and a pool of data to base decisions on - and, most importantly, a ‘link’ between both. To varying extents, these providers provide an integration that helps route traffic based on certain variables such as a web user’s country of origin, their ISP, or any other data source.
Currently, there are some major differences between the providers in this category. What sets them apart is the degree of ‘integration’ between the DNS and data. To illustrate the differences we’ve included additional information on their individual pages, in the form of the following diagram:
Illustrates no integration; this can mean two separate providers of the performance data and CDN balancing or one provider, that offers both products but completely separate from each other.
The performance data and CDN balancing technology are linked and distributing traffic based on the performance data is possible.
Both products are integrated and configuration and customisation of the traffic distribution is possible.
CDN balancing means the weighted distribution of user traffic between CDN providers and their points-of-presence. User traffic to your website is distributed over a number of edge servers in locations all over the globe to reduce latency.
On Multi-CDN Overview we refer to the functionality as CDN balancing, though in essence it’s DNS management. To optimise the performance of your site, a DNS provider can offer the functionality to distribute traffic across multiple CDNs and endpoints.
With just CDN balancing technology, what lacks is the data to base CDN decisions on, and of course different CDNs to balance between. Examples of Managed DNS providers are DNSimple, Amazon Route 53, easyDNS, DNS Made Easy, Google Cloud DNS and Neustar UltraDNS.
CDN providers can provide managed DNS services that are natively integrated with their CDN platforms. To operate a CDN network, an internal DNS solution of some shape or form is required. As it’s already a part of a provider’s infrastructure, it makes sense to resell it as a service to clients.
The offering can be considered part of a one-stop-shop strategy for CDN providers, that can also include hosting and other web optimisation services.
CDN providers with a DNS service are (in random order):
Performance data is not included, nor are additional CDNs, making this combination of CDN and DNS offering less suitable for a multi-CDN setup.
One provider that offers all three components in one integrated solution. Clients get a fully integrated multi-CDN solution from a single provider, and do not have to enlist the services of more than one party.
A solution like this is extremely suitable for businesses who do not want to set up their own multi-CDN and bear responsibility for its maintenance. Additionally, working with a single provider eliminates the need for multiple contracts and contract partners.
An important note here is that the level of integration still varies and that at present the multi-CDN providers in the market vary greatly from each other. In this overview, the individual pages and in the comparisons we strive to make the difference between multi-CDN providers clear.
Don’t hesitate to get in touch with any questions about multi-CDN, DNS and CDN balancing, performance data or the individual CDNs.