Emergence of telco CDNs The rapid growth of
streaming video traffic required large
capital expenditures by broadband providers in order to meet this demand and retain subscribers by delivering a sufficiently good
quality of experience. To address this,
telecommunications service providers have begun to launch their own content delivery networks as a means to lessen the demands on the
network backbone and reduce infrastructure investments.
Telco CDN advantages Because they own the networks over which video content is transmitted,
telco CDNs have advantages over traditional CDNs. They own the
last mile and can deliver content closer to the end-user because it can be cached deep in their networks. This deep caching minimizes the
distance that video data travels over the general Internet and delivers it more quickly and reliably. Telco CDNs also have a built-in cost advantage since traditional CDNs must lease bandwidth from them and build the operator's margin into their own cost model. In addition, by operating their own content delivery infrastructure, telco operators have better control over the utilization of their resources. Content management operations performed by CDNs are usually applied without (or with very limited) information about the network (e.g., topology, utilization etc.) of the telco-operators with which they interact or have business relationships. These pose a number of challenges for the telco-operators who have a limited sphere of action in face of the impact of these operations on the utilization of their resources. In contrast, the deployment of telco-CDNs allows operators to implement their own content management operations, which enables them to have a better control over the utilization of their resources and, as such, provide better quality of service and experience to their end users.
Federated CDNs and Open Caching In June 2011, StreamingMedia.com reported that a group of TSPs had founded an Operator Carrier Exchange (OCX) to interconnect their networks and compete more directly against large traditional CDNs like
Akamai and
Limelight Networks, which have extensive PoPs worldwide. This way, telcos are building a Federated CDN offering, which is more interesting for a
content provider willing to deliver its content to the aggregated audience of this federation. It is likely that in a near future, other telco CDN federations will be created. They will grow by enrollment of new telcos joining the federation and bringing network presence and their Internet subscriber bases to the existing ones. The Open Caching specification by
Streaming Video Technology Alliance defines a set of
APIs that allows a Content Provider to deliver its content using several CDNs in a consistent way, seeing each CDN provider the same way through these APIs.
Multi CDN and CDN selection Combining several CDN services allow Content Providers to not rely on a single CDN service, especially concerned to deal with high peak audience during live events. There are several ways to allocate traffic to a particular CDN among the list, either client-side CDN selection, or server-side (at the Content Provider's origin) or cloud-side (in the middle, between the content origin and the audience). CDN selection criteria can be performance, availability and cost.
Improving CDN performance using Extension Mechanisms for DNS , which is intended to accurately localize DNS resolution responses. The initiative involves a limited number of leading DNS service providers, such as
Google Public DNS, and CDN service providers as well. With the edns-client-subnet
EDNS0 option, CDNs can now utilize the IP address of the requesting client's subnet when resolving DNS requests. This approach, called end-user mapping,
CDN using non-HTTP delivery To boost performance, delivery to clients from servers can use alternate non-HTTP protocols such as
WebRTC and
WebSockets.
Image Optimization and Delivery (Image CDNs) In 2017, Addy Osmani of
Google started referring to software solutions that could integrate naturally with the
Responsive Web Design paradigm (with particular reference to the element) as
Image CDNs. The expression referred to the ability of a web architecture to serve multiple versions of the same image through HTTP, depending on the properties of the browser requesting it, as determined by either the browser or the server-side logic. The purpose of Image CDNs was, in Google's vision, to serve high-quality images (or, better, images perceived as high-quality by the human eye) while preserving download speed, thus contributing to a great
User experience (UX). Arguably, the
Image CDN term was originally a misnomer, as neither
Cloudinary nor Imgix (the examples quoted by Google in the 2017 guide by Addy Osmani) were, at the time, a CDN in the classical sense of the term. or integrating with one of the existing CDNs (Cloudinary/Akamai, Imgix/Fastly). While providing a universally agreed-on definition of what an Image CDN is may not be possible, generally speaking, an Image CDN supports the following three components: • A Content Delivery Network (CDN) for the fast serving of images. • Image manipulation and optimization, either on-the-fly through
URL directives, in batch mode (through manual upload of images) or fully automatic (or a combination of these). • Device Detection (also known as Device Intelligence), i.e. the ability to determine the properties of the requesting browser and/or device through analysis of the
User-Agent string,
HTTP Accept headers, Client-Hints or
JavaScript. == Content delivery service and technology providers ==