 For the applications which are available for provisioning on content delivery networks, the most important much yearned for and complex to provide are the on-demand video services as well as live streaming services. How are these provided? Let's look at an interesting case study. Basically, if we want to provide video services, it's no more a simple thing to do because we are interested in offering services which involve real-time delivery. So we need a platform which is based on the NGN IP based core to offer services at a country wide scale. For that, there is a very interesting example from IPTV from Poland. We are going to look at it in detail. What they provided at the national level was IPTV broadcasting service involving live TV programming, video on demand, audio on demand only, and then time shifting which is the movement of the cursor on the scroll bar to the desired place in the video. It is easy to be done in streaming, but it's not possible in live. You can do that for the past video shots, but you can't of course do it for future. Then electronic program guide which is more of a directory service and video recording features. Now for an application which has to incorporate all these interesting features at the national scale is going to become very complex. The challenges which are going to emerge are high volumes of data. The transmission rate is going to increase tremendously. If we assume that a video session requires around 1 megabits per second, still if we aggregate it, this turns out to be very large. So if we think about a centralized video service, it is impossible to realize. So a content delivery network becomes our compulsion. Once we have CDN, we inherit the beautiful features that we are already aware of. So we need to provide replication, caching, nodal placement and access mechanisms. All this under the umbrella of a certain quality of service which is part of the service level agreement between the user and the provider. For that some measurement and monitoring activity would be required. So this is basically Polish TV, ITVP. It has been designed as CDN in a hierarchical manner. What they have done is they split the entire country into regions and each region has its own registry or directory. Functional encoding formats are provided on the CDN which are suited for delivery on small screen sizes, set-top boxes for smart televisions and for personal computers and laptops. The overall design of the ITV is from the functional and organizational structure defined. From the functional viewpoint, ITVP addresses the content delivery, its monitoring, the overall management and control plus reporting format. The organizational structure is such that there are exclusive third-party content providers, then the CDN operator which in this case is the Polish government or Polish state because ITV is a state-owned television. And the network providers which are again competitors or commercial enterprises in the form of ISPs. This is the complete technology platform for ITVP. It's very simple to understand. We have the content provider system which have different encoding formats. They have their own repository for videos, music and live transmission. There is a way for them to publicize their content and to keep it secure. Upon content request, the content is provided to the content delivery network. The content delivery network is the main focus because it is the state-owned television. So the Polish government came up with the overall management of the CDN. Here there are of course management entities which oversee the distribution of this content from the content provider system. They actually have a two-level or hierarchically two-state system. They have the regional content centers which are used for replication and the proxing or cashier services which are used only for localized cashier or content storage for short time. Then the content delivery is done to the users through the internet service providers. We also see we have the customer relationship management system, the interface or the portal and the relationship of the interactive portal is established for licensed usage through a licensed management system. This is the platform but this platform is going to be usable at the larger scale through the incorporation of a content delivery network. The CDN has always handled a trade-off between competing interests. For instance, the quality of service expected from the users is very high but it all depends upon the overall cost incurred to incorporate replication and caching servers. For that the state government decided to provide a mix of these by incorporating a limited number of replication and caching servers. The mode of delivery is either download and play which is more like file transfer or streaming service and for streaming is for stored content as well as for live content. The content delivery network architecture specifically in the case of IITVP has a two layered hierarchical setup where we have the original content servers from the content providers. We have got different regions with their central registries and the replication is taking place at the regional level but for last mile the proxying or caching is taking place. This is the overall architecture. Now a point to be noted is that this is at national scale so the state will and the state infrastructure is at the disposal of IITVP. This is taken from content delivery networks by Raj Kumar Bhaiya and Mr. Prathan.