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CDN interoperability covers not only the interconnection of CDNs but also other interconnections such as with Pay TV systems, Content Management Systems (CMS) or encoders/head-ends have to take into account as well, both from a business and from a technical point of view. Velocix provides a wide range of capabilities and APIs to facilitatate those tasks both to Service Providers and Content Owners.

In the deployment of CDN technologies, it is becoming increasingly important to ensure a single CDN solution can be deployed that meets the requirements of multiple internal business units/affiliates. Whether this is for the provision of CDN services for IPTV, VOD and Mobile platforms or for the provision of these services across multiple geographies and instances of the network, interoperability is key.


CDN Interconnection/Federation

Interconnected delivery networks is one of the key aspects of expanding a content delivery solution from a single network or regional deployment into a wider ecosystem solution.  Today's Service Provider CDNs currently operate as non interconnected islands. This pushes too much complexity onto the Content Providers. To achieve true success Service Provides need to enable Content Providers to have easy and simple access to delivery networks.

The following is an overview of the various models, although this list is not exhaustive it does form the basis of the most common interconnect models:


  • Independent – In the independent model multiple CDN instances using the same or  different CDN technologies/platforms are deployed but no interconnection is  available between the CDN’s.
  • Global /  Multi-tenant – This is the most common of CDN deployment models, this model  works by deploying a single instance of a CDN, within either a national  geography or globally but with a centralised management and control  infrastructure. This national or global CDN is based on a common technology  platform and managed as a single instance or single CDN. The CDN is able to deal  with multiple tenants (content owners/providers of content).
  • Subsidiary – This model uses a common CDN technology.   Multiple instances of the CDN platform are deployed (geographically) and  these instances are managed by a primary CDN.   Content delivery is kept within individual CDN instances and does not  leverage delivery or storage resources from other CDN’s. A level of control is  typically provided to the subsidiary CDN’s for the provision and management of  CDN accounts.
  • Secondary  CDN – This model assumes a single CDN is the primary CDN instance. This CDN  under specified conditions will be able to fallback or delegate CDN delivery to  a secondary CDN, this can either be a CDN based on the same or different  technology/platform.
  • CDN Load  Balancing - CDN customer publishes content into multiple CDNs and places a  CDN selector or load balancer in front of those networks. Networks act  independently
  • Homogenous  Federation – This model follows the regional model but provides autonomy in  the control of the subsidiary CDN’s. Through a centralised management  capability the federation of content across the multiple CDN instances is also  enabled.  This provides a balance of  ownership and control to subsidiary CDN’s whilst allowing (where policy  permits) the sharing of all CDN resources. Being a homogeneous model the CDN  technologies/platforms will be the same.
  • Heterogeneous  Federation – This model again follows the regional model and provides more  autonomy in the control of the subsidiary CDN’s with a centralised management capability  the federation of content across the multiple CDN instances. Being a  heterogeneous model the CDN technologies/platforms will typically be different.  This model is the aspired CDN model but depends on agreed CDN standardization  to achieve.

Velocix is working closely with the standards organization such as IETF (CDNI WG), ETSI (TC TISPAN & TC MCD) and ATIS (IIF & CSF) to ensure the global interoperability, from business and technical perpectives, of CDN networks and to provide a flexible framework for Service Providers to choose their preferred deployment model with complete confidence that it can adapt and grow as their business expands.


Exposed APIs

APIs are the key bridges between the CDN as a set of programmable and controllable network capabilities and external systems. APIs enable all actors involved in the video value chain, and specially Service Providers and Content Providers, to deploy new services with faster time to market, develop market differentiators and simplify integration with 3rd party components. Velocix is continuously enriching its existing range of APIs, for example:

  • Expanded  provisioning and control APIs exposed as RESTful interfaces.
  • Monitoring  and performance MIBs with real-time data on the topology and performance of the  whole CDN to help the network operator better identify network regions that are  ‘overloaded’, design troubleshooting configurations and upgrade scenarios.
  • Atom-based  programmatic feeds for log retrieval & aggregation and additional real time  log event notifications.
  • Additional  acquisition and distribution protocol support, including support for ATIS C2  acquisition interface, multicast pre-positioning and Web-DAV publication of  content.
  • Authorization  APIs for integration with external authorisation and policy functions,  integration with BGP/IGP feeds, ALTO maps, support for Dynamic Site Acceleration  and per-stream encryption and protection.


ATIS C2 acquisition interface

This interface enables Velocix CDNs to support existing VoD systems, acting as an intelligent caching hierarchy for cable RTSP streamers to enable Service Providers to use their investment in a Velocix CDN for supporting their current and future IP content delivery technologies and devices while leveraging their sunk investments in existing edge RTSP delivery servers. Through this interface, Delivery Appliances at the edge of a Velocix CDN act as an ATIS C2 Origin for cable RTSP streamers. Velocix CDN acquires content from "real" C2 Origin and provides distribution & caching hierarchy video distribution network.

This advanced capability allows:

  • RTSP Video on Demand to Set To Box (STB)
  • Current & future IP (HTTP/RTMP/etc) delivery to other screens (PC, Tablet, etc.)Support multi-tenancy, CDN interconnect with simplified path and query parameters
  • G2 Configuration validation; check G2 configuration without having to have test heads/machines in every location
  • Allows an external system to extract routing information and send an HTTP request to serve from specific appliances
  • Content Provider
  • Playlist generation
  • CDN Selector
  • Implementation of proprietary request routing protocols  (e.g. NGOD C2 Locate protocol)


ALTO inferface

Application-Layer Traffic Optimization (ALTO) interface enables a Service Provider to have additional controls and apply application-specific policies over how their network topology and costs are exposed to individual applications (i.e. CDN). This allows more flexible ways to monetise video traffic. Additionally it provides the ability to enable a Service Provider to maintain a functional separation between their routing plane and network topology map computation functions.

These advanced capabilities on top of direct routing plane integration provides a number of benefits, for example:

  • Provides  a filtered view of the network and/or cost map that relates to CDN locations,  and their proximity to end users, for example to allow the Service Provider to  control the level of topology detail they are willing to share with the CDN.
  • May apply  additional policies to the network map and cost information to provide a  CDN-specific view of the network map/cost, for example to allow the Service  Provider to encourage the CDN to use network links that would not ordinarily be  preferred by a shortest path first routing calculation.
  • The  routing plane may be operated and controlled by a different operational entity  (even within a single Service Provider) to the CDN and the ALTO service could  provide a layer of separation if the Service Provider is uncomfortable or  unwilling to allow the CDN to directly integrate with the routing plane, or if  the routing plane and the CDN are operated by different operational entities/groups (including  different entities within the same Service Provider).


CMS and Origin Server integration

In order to make content such as Video on Demand (VOD) catalogues available for distribution via the Velocix CDN they are first ingested or published into the CDN.  In order to integrate seamlessly with established workflows and Content Management Systems, the Velocix CDN provides a wide range of flexible, industry standard interfaces to accommodate this such as; FTP / FTPeS, RSYNC, Aspera, WebDAV, Rest HTTP and Vx XML/RPC. In addition to that, Velocix provides extensive programmatic API capabilities to enable tight integration with Content Management Systems and processes enabling the Content Owner to fully automate their content publishing & management workflow.

Velocix also supports Reverse Proxy Acquisition to pull any format of HTTP Adaptive Streaming content directly from an Origin Server, or encoder depeding on the format.  The Origin Server is the first element in the cache chain: it ensures that every single object is available and delivers it through Reverse Proxy Acquisition when the object is requested through its URL by a Shield cache or an end device.

The Velocix solution has been integrated with a number of CMS systems such as thePlatform, ALU 5910 MCM and VidZapper as well as it is fully integrated with its in-house on-net Origin Appliance.