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This chapter provides a basic conceptual and functional overview of the E-CDN application, including the Content Distribution Manager, Content Routers, and Content Engines that make up the Content Delivery Network (CDN), as well as the architecture (SODA) that enables the E-CDN application to manage content efficiently. This chapter contains the following sections:
Cisco Application and Content Networking Software (ACNS) is a software platform that unifies the Cisco E-CDN application features and the Cisco Cache software features into a single software platform. ACNS software is supported on Content Engines, Content Distribution Managers, and Content Routers. (See the "Platform and Operating System Requirements" section.)
For more information about the Cisco Cache software, refer to the Cisco Application and Content Networking Software Caching Configuration Guide.
The E-CDN application offers accelerated content delivery, hosting, and other content-based services. It addresses the need to distribute and receive high-bandwidth, media-rich content across the Internet or an intranet without performance losses or content delivery delays.
When the ACNS E-CDN application is enabled, Content Engines, Content Routers, Content Services Switches, and Content Distribution Managers can be deployed to create a complete Content Delivery Network system. This system includes content routing, content switching (using the Content Services Switch (CSS) switch), content distribution and management, and content services, as well as content delivery. Figure 1-1 shows a typical E-CDN application topology.
The E-CDN application allows organizations to maximize the impact of web communications by making possible the rapid delivery of high-quality video, rich audio, large graphics, presentations, and documents over corporate LANs, WANs, and other broadband networks.
This guide provides instructions on the use and administration of the E-CDN application, including the Content Distribution Manager, which includes a web-based user interface that is the main conduit to the network for users and administrators. The Content Distribution Manager includes features for configuring new devices and users on the E-CDN application, creating and populating content channels, allocating bandwidth, viewing media over the CDN, and more.
Using the E-CDN application (see Figure 1-1), Internet devices take advantage of Self-Organizing Distributed Architecture (SODA) to efficiently manage high-bandwidth content. SODA enables your organization to leverage existing bandwidth to deliver high-quality media to the desktops of target audiences within your organization.
Self-Organizing Distributed Architecture (SODA) is a proprietary technology that uses sophisticated algorithms to efficiently manage high-bandwidth media over office networks or even over the Internet. The foundation of the E-CDN application software, SODA eliminates network bottlenecks that often accompany large multimedia streaming products.
Content Engines deliver media to desktop users without the typical delays and latency associated with high-bandwidth media streaming through a data network. All the network administrator or desktop user needs to review media is a standard web browser and media player, such as Internet Explorer and Windows Media Player.
To take advantage of SODA technology, a Content Distribution Manager and at least one Content Engine must be installed on your network. The E-CDN application is scalable to multiple sites through the addition of Content Engines and Content Routers to the network.
The Content Distribution Manager connects to your corporate data network and replicates media to the connected Content Engines through Content Routers located across your LAN. The Content Distribution Manager:
Through the interface you can:
Access the Content Distribution Manager interface from your browser by entering the Content Distribution Manager URL or IP address.
The Content Engine is a device that supports many concurrent streams of Moving Picture Experts Group (MPEG) video or other rich media types. As a remote device attached to your company LAN, the Content Engine identifies itself to the Content Distribution Manager and is subscribed to one or more content channels using the Content Distribution Manager subscriber feature. Once subscribed, Content Engines begin receiving media files for each channel from the Content Distribution Manager. Media files are stored locally on the Content Engine and streamed to end user desktops on demand.
When end users request a media file from the Content Distribution Manager, the Content Distribution Manager sends a redirect to the client's browser redirecting the client to a Content Engine that is local to the user. The client's browser then requests the media from the Content Engine which was selected by the Content Distribution Manager. Using SODA technology, Content Engines are able to calculate the fastest and most efficient route for replication of media and to optimize the allocation of replication bandwidth.
Content Routers assist the Content Distribution Manager and serve as backups if the Content Distribution Manager suddenly goes offline. This means that
Content Routers allow request redirection to continue, but administrative capabilities are lost. Like Content Distribution Managers, Content Routers store routing hierarchies for CDN devices and can route playback requests from end users to Content Engines, and send the "keepalive" messages that prevent Content Engines from going offline if the Content Distribution Manager is unavailable.
Unlike Content Distribution Managers, there can be multiple Content Routers dispersed throughout the CDN. Also unlike Content Distribution Managers, Content Routers do not create or manage channel content (Content Routers can be subscribed to only the manual upgrade channel when it exists), nor do they store or perform bulk replication of data.
Decisions about which devices on your E-CDN application serve a particular request for content are made by the ACNS 4.1 software using a powerful organizing model. In the simplest scenario, requests from workstations on the CDN are routed to the nearest Content Engine on their network. However, CDN administrators can override the CDN default settings and influence content routing through the deployment of "preferred coverage zones" and "regular coverage zones" for Content Engines and the Content Distribution Manager.
Preferred coverage zones are ranges of IP addresses assigned to Content Engines or the Content Distribution Manager. When a request for content originates from an address within the preferred coverage zone of a device, that device (which could be a Content Engine or the Content Distribution Manager) is selected to serve that request.
All requests originating from outside the preferred coverage zones for your CDN devices (that is, requests from a "regular" zone) are processed by the nearest device. The "nearness" of a device is derived from the local network segment each device is on, as determined by its IP address and network mask.
When content requests originate from addresses that are covered by more than one preferred coverage zone or regular coverage zone, the Content Distribution Manager chooses from among the qualified Content Engines in serving the request.
The E-CDN application supports any standard media format for import and distribution. Among the supported file types are:
Media is imported to the Content Distribution Manager in an efficient manner and is downloaded to Content Engines according to bandwidth constraints you set. Using a web browser, users can view these media files on their PCs.
From a Content Distribution Manager, you can import and replicate, or distribute, your media files to Content Engines. The network uses standard Internet TCP/IP protocols for all communication.
All transfers are fault-tolerant. This means that if a file transfer is interrupted, the replication process picks up where it left off, rather than resending the entire channel.
Users and CDN administrators interact with the E-CDN application using a web-based graphical user interface to the Content Distribution Manager that provides easy access to most CDN functions. The following minimum hardware and software requirements apply to each machine that will be used as a workstation to access the Content Distribution Manager.
Microsoft Internet Explorer 5.0/5.5 or Netscape Communicator Version 4.7
Cisco IOS Software Release 12.2(4)T is required for support of Resource Reservation Protocol (RSVP), Quality of Service (QoS), and multicast.
Posted: Mon Mar 24 16:18:10 PST 2003
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