CDN federation, standards
The number of deployed CDNs within telcos and hosting providers is growing fast. We have deployed a lot of CDNs in the past year, and there is a waiting list for deployments for this year. The need for connecting CDNs together is growing. This post gives more details about our inter-CDN / CDN federation standards and the pilots we do in this area.
I have been pitching CDN integration since 2002. I foresaw that -next to global CDNs- there would be an increasing need for on-net CDNs, for multiple reasons, and that these CDNs could be used to offload internet content for global CDNs and large content owners. Small CDNs needed to be linked together, so they can form a federated CDN. The best way to do this is with CDN overflow and overlay technology that we have built into our CDN suite, which allows you to add other CDNs as if they were logical edge servers within your own CDN.
There have been multiple initiatives in the past, especially in the Netherlands. Some initiatives were private, commercial initiatives. Their technology was extremely limited: Windows Media live streaming only, with manual publishing point setup and a simple redirector. So this wasn’t truly usable for generic purposes. But the real problem was that the initiator wanted to keep this system closed, the ISP’s and content owners objected.
After we pitched our ideas to the neutral AMS-IX, we successfully got the leading ISP’s and content owners in one room, which was a nice first achievement. Other ideas were pitched as well:
- Multicasting. But that wasn’t going to happen on the web, and this doesn’t work for VOD.
- A huge farm at the AMS-IX site. But that didn’t really offload traffic deeper into the telco networks.
- A broadcaster operated CDN with edge servers in the telco networks. The telcos object to this. They don’t want content owners to deploy black boxes inside their network, because that would mean the end of control over the network. And it would become a mess if every content owner (Youtube, Google, broadcasters, other CDNs) would each deploy their servers in the telco networks. The telcos would have to cope with fast increasing traffic loads, without any control over traffic in their network, even smaller margins on broadband services and zero revenue for traffic. It is a wrong assumption that content can freely be offloaded (by free peering or by edge servers) within telco networks.
- So the only viable solution would be – and still is – telcos deploying CDNs and broadcasters deploying overlay CDNs.
CDN federation pilot
We are doing a full CDN federation project in the Netherlands with the Dutch Public Broadcasting Organization (NPO, best compared to the BBC), Tier-1 telco KPN and academic high-speed network SURFnet. The StreamZilla CDN, the KPN CDN and the SURFnet CDN are acting as logical edge servers for the NPO CDN. This actually is a matter of setting up a normal content owners account on one CDN, and then entering the account details to the overlay CDN as if this account is an edge server.
By defining geo regions in the NPO CDN, and by matching these regions to the various federated CDNs, NPO can now optimize geo delivery overall, and the underlying CDNs can optimize geo delivery within their CDN.
The interconnected CDNs automatically take care of all inter-CDN processes such as content distribution, management of live streams relaying, geo load balancing of users, monitoring, reporting, logs and statistics (for usage reporting, also for billing).
All these CDNs are powered by our VDO-X CDN software suite. We are only using open internet standards based protocols and open internet standards based API’s for the inter-CDN communication. We use the pilot to further develop the API’s so we can publish these as proposed standards. This will allow other CDNs to plug in as well and become a part of a federated CDN or become an overlay CDN. If their technology is up to it, because these advanced features do require a modern CDN architecture.
ETSI standardization
Together with KPN we have been working on getting CDN federation standardization into ETSI, the European Telecommunications Standards Institute. ETSI had already been working on CDN standardization, but IMHO this was only focussed on IPTV instead of generic CDNs, and was locking the standard too much into specific technologies. Good news is that members such as KPN, TNO, ZTE and Samsung have supported the open CDN interconnection ideas so ETSI can now work on CDN federation standardization.
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