Configuring Streaming Media Services

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  • 1. C H A P T E R9 Configuring Streaming Media ServicesStreaming media services enable the delivery of digital media directly to the end user from a point of origin, such as an origin server, encoder, or Content Engine cache. Streaming media can be delivered as live content, or it can be delivered as on-demand content, such as video on demand (VoD). Cisco ACNS software supports several types of streaming media services, including RealNetworks RealMedia, Microsoft Windows Media Technologies (WMT), Apple QuickTime, and Cisco Streaming Engine. This chapter discusses these supported streaming media services and explains how to enable these services on Content Engines in your ACNS network. This chapter contains the following sections: Content Engine Streaming Overview, page 9-1 Licensing and Enabling Streaming Servers, page 9-6 Using the Real-Time Streaming Protocol Gateway, page 9-7 Using Windows Media Technologies, page 9-15 Configuring Weighted Load Balancing for Live Stream Splitting, page 9-38 Configuring Bandwidth Settings for Content Services, page 9-40Note Content Engines that use a Content Service Switch (CSS) to load balance streaming traffic cannot stream UDP traffic (such as RTSPU) because the Content Service Switch does not support UDP traffic.Content Engine Streaming Overview Content Engines deployed in a centrally managed ACNS network provide both live and recorded streaming media services. Live video streaming and recorded video streaming services (such as video-on-demand streaming) address various challenges in the field of corporate communications. This section describes some of these communication challenges and explains which streaming solution is best suited to meet your corporate communication needs. Corporate communications can include company meetings, state of the business addresses, quarterly earnings broadcasts, web casts, emergency broadcasts, company television, and so forth. Live streaming events often include supplemental media, such as slide presentations, polling, Q&A, and live chat. One of the primary challenges in todays corporate environment is to deliver video and audio communications to employees, partners, and company stakeholders globally at the same time, and to safely deploy such media-rich content without adversely impacting existing employee work applications. Cisco ACNS Software Configuration Guide for Centrally Managed Deployments, Release 5.5 OL-9136-01 9-1

2. Chapter 9 Configuring Streaming Media Services Content Engine Streaming OverviewWhile live video streaming enables corporate executives to provide the same message to all potentialviewers at the same time and is an engaging, inexpensive means to reach all employees, largeinternational companies can encounter challenges with live streaming because of time zone differencesand bandwidth constrictions.Live streaming is limited by the amount of available WAN bandwidth so that remote sites on lowbandwidth WANs are not be able to participate in a live video streaming event. However, it is possibleto reach low bandwidth (64-Kbps) sites with an audio-only stream because audio consumes only about12 to 20 Kbps per client. Another way to resolve time zone and bandwidth challenges is to use cachedvideo streaming or video on demand (VoD). Live Streaming for the Non-Multicast Enabled NetworkA publicly announced live streaming event is the single most taxing event on a non-multicast enablednetwork and on the origin servers. In a live streaming event that does not take advantage of networkmulticast or application-level stream splitting, a separate stream is created from every single client to theoriginating server. The strain caused by such excessive traffic between clients and servers can cause thenetwork to collapse.For example, in a network with 10,000 users, if the stream encoding rate is reasonably high (around300 kbps), the media server or video server would have to deliver the video stream at a rate of 3 Gbps.In a data center deployment, the data center would require a large number of video servers to support theevent, while in all probability, the rest of the network would collapse before the video servers could evenreceive all the requests. If a WAN exists between the users and the video servers, the strain iscompounded. If collateral content (such as images, which can often be as large as 100 KB per object) isincluded for the event, and 10,000 users simultaneously request this content, the web servers that servethese types of objects would likely fail. (A typical web server can send 1000 objects per second.)In such a network scenario, strategically placed Cisco ACNS Content Engines can minimize the impactof a live streaming event on the network by providing local delivery of those objects. Content Enginesalso support unicast live stream splitting. Unicast Live Stream SplittingUnicast live stream splitting is a solution for corporate networks that do not support multicasting or foradministrators who must provide live streaming for unplanned events. A Content Engine placed witheach WAN router provides unicast stream splitting for live streams that originate on the non-multicastenabled Internet or the within the corporate intranet. (See Figure 9-1.)Cisco ACNS Software Configuration Guide for Centrally Managed Deployments, Release 5.5 9-2OL-9136-01 3. Chapter 9Configuring Streaming Media ServicesContent Engine Streaming Overview Figure 9-1 Unicast Live Stream Splitting2 2Unicast WAN 1 151590 DNS WWW Video server 1Live Unicast Video2Multiple Unicast Streams (One per User) Content Engine unicast stream splitting provides the following benefits: Companies do not have to upgrade network infrastructure to deploy IP multicast, if that is achallenge. Administrators do not have to create scheduled multicast events because Content Enginesautomatically split the stream. The Content Engines cause very little delay compared to delays incurred by the encoder, encoderbuffer, and media player buffer. Users can view the broadcast as it occurs. In all circumstances, however, live video quality is affected by the available WAN bandwidth. Also, when live streams are being delivered to remote sites, you must have a full duplex-switched Ethernet LAN infrastructure at the remote site because every client pulls a separate unicast stream. Hybrid Unicast-to-Multicast Live Streaming Unicast-to-multicast streaming is a solution similar to stream splitting, except that in final delivery segment the stream is converted to multicast to minimize the bandwidth usage impact on the network and to minimize the load on the Content Engine. With unicast-to-multicast streaming, if you have a Content Engine in the same location as your clients, the Content Engine can acquire the stream as a single unicast stream over the WAN and convert it to a multicast in the LAN. Cisco ACNS Software Configuration Guide for Centrally Managed Deployments, Release 5.5OL-9136-019-3 4. Chapter 9 Configuring Streaming Media ServicesContent Engine Streaming Overview If you have a multicast-enabled WAN, you can use a Content Engine to publish the multicast in the data center and stream the multicast to all your multicast-enabled clients over the WAN. Multicast-enabled network routers and switches replicate (or copy) the stream (packets) where necessary so that all users can view the video event simultaneously. (See Figure 9-2.)Figure 9-2 Hybrid Unicast to Multicast Live Streaming 22 UnicastWAN1 151588 DNSWWW Video server1Live Unicast Stream 2Single Multicast StreamReplicated by Network Video On Demand Streaming Video on demand (VoD) streaming can be used to deliver communications across large international company networks where WAN bandwidth and time zone differences present a challenge. With VoD you can deliver the same message to everyone in your organization, everywhere, anytime. In a network with no Content Engines deployed, each client VoD request generates a separate stream from the video server across the WAN. The aggregate bandwidth usage of all clients must be less than the available WAN bandwidth or serious congestion will occur. When you place a Content Engine in the same location as the requesting client, you remove the WAN bottleneck, and the client can have an experience that is more media rich than the original live broadcast. VoD streaming uses a recorded file that is usually generated from a live event. This file takes the form of a Windows Media file (wma, wmv, asf, and so forth), a RealMedia file (rm, ra, and so forth), or a standard video file (such as, mpg, mp4, mov). The video file can be administratively pre-positioned to the local Content Engine file system using the intelligent and controlled file distribution capabilities ofCisco ACNS Software Configuration Guide for Centrally Managed Deployments, Release 5.59-4 OL-9136-01 5. Chapter 9Configuring Streaming Media ServicesContent Engine Streaming Overview ACNS software, or the file can be retrieved and stored in the Content Engine file system as a result of a client request. Regardless, once the file is in the Content Engine file system, the file can be delivered locally across the LAN. Video storage requirements are generally calculated in hours. If the stream encoding rate is 300 Kbps, then an hour of video consumes 300,000 bits/second x 3,600 seconds/hour x 8 bits/Byte for a total of 135 MB. Based on these estimates, a Content Engine with a 40-GB capacity can store about 296 hours of video. Demand-Cached Video Demand caching (also called pull caching) allows the Content Engine to dynamically populate its cache in response to user requests. Caching is useful when the video encoding rate (or streaming rate) is less than the available WAN bandwidth, but not enough bandwidth exists for multiple clients to view the video simultaneously. Caching is the only solution if the organization that controls the Content Engine does not have access to the video files before a client requests the files. This situation can occur when the content originates outside the organization, from the Internet, or from a partner. A primary advantage to demand caching is that it does not require any administration. The disadvantage is that the first user requesting the video can experience poor quality if the network is congested. (See Figure 9-3.)Figure 9-3 Demand-Cached Video 21Internetor WAN1 151587 DNS WWW Video server1First Request 2Subsequent Requests Cisco ACNS Software Configuration Guide for Centrally Managed Deployments, Release 5.5OL-9136-019-5 6. Chapter 9 Configuring Streaming Media Services Licensing and Enabling Streaming Servers Pre-Positioned Video Pre-positioned video involves prepopulating Content Engines with the recorded video program. When a recorded video is company-owned or can be acquired, the company administrator can program a Content Engine to fetch the specifically named content or files from an origin server, set bandwidth distribution controls, and configure the Content Engine to automatically distribute the recorded files to Content Engines at the edge of the company LAN. Users can join a scheduled broadcast of the video, or the video can be made available on demand from a link published on the company website. (See Figure 9-4.)Figure 9-4 Pre-Positioned Video22Internetor WAN1151589 DNS WWWVideo server 1 Pre-positioning2 All Requests Licensing and Enabling Streaming Servers For your ACNS network devices to be able to serve streaming media, you must tell the ACNS network that a particular streaming media service is present, and you must accept a licence agreement for each type of media service that you intend to use. Media services available in ACNS 5.x software include Windows Media Server, RealProxy, RealSubscriber, and multicast client. NoteCisco Streaming Engine does not require a separate license agreement.Cisco ACNS Software Configuration Guide for Centrally Managed Deployments, Release 5.5 9-6 OL-9136-01 7. Chapter 9 Configuring Streaming Media Services Using the Real-Time Streaming Protocol Gateway You can accept license agreements at the device level or at the device group level. As soon as any license agreement has been accepted for any device or device group, the acceptance is applied to all devices that are currently registered to the Content Distribution Manager and to all devices that register in the future. When a Content Distribution Manager is upgraded to ACNS 5.5 software, the Content Distribution Manager will apply any accepted license agreements from the previous ACNS software release to all registered devices in the network. If in a previous ACNS 5.x Release, you accepted a particular licence agreement on some, but not all, devices, any device for which the license was not accepted prior to the Content Distribution Manager upgrade will have its license agreement accepted automatically. NoteYou cannot remove a license agreement once it has been accepted. If there is a particular media type that you do not want to serve through your ACNS network, you need to disable the corresponding media player so that your ACNS network devices do not attempt to serve that media type.Using the media player mappings in the manifest file, you can customize your content type mappings from MIME content types or file extensions to configured media players. (See the Working with Manifest Files section on page A-6 for more information on configuring manifest files.) NoteModifying the configuration of any media players causes any ACNS network devices running that media player software to restart and register the configuration change. Depending on the number and location of devices that restart following a media player configuration change, you may experience a temporary interruption in service for the time it takes your devices to come back onlineusually a few minutes.Before enabling licenses for streaming media services, make sure that the clock and calendar settings on the ACNS network device are correct; otherwise, you will see an error message, and the services will fail to install. Use the show clock EXEC command to display the system clock. To set the system clock, use the clock set EXEC command.Using the Real-Time Streaming Protocol Gateway The Real-Time Streaming Protocol (RTSP) is a standard Internet streaming control protocol (RFC 2326). It is a widely used application-level protocol that controls the delivery of data with real-time properties, such as video and audio. Apple QuickTime, RealNetworks, and the Cisco Streaming Engine use RTSP as a streaming control protocol. The RTSP gateway is a process running on the Content Engine that accepts an RTSP request and performs the initial RTSP contact with RTSP-based clients (RealMedia, QuickTime, and so on) on behalf of the RTSP-based streaming servers available on the Content Engine. From information derived from the initial request operation, the RTSP gateway queries the URL filtering, rules, authentication, and unified name space...


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