Many organizations use video for communications that are not time sensitive, (for example, training sessions and prerecorded messages to employees). Communicating messages through videos is not only cost effective but also convenient when the audience is spread across time zones. However, videos consume a lot of bandwidth when played over the Internet. Insufficient bandwidth causes latency, which affects the user experience and degrades the impact of video communication.
Video caching improves the viewing experience for HTTP video streams, especially on slower links. The video cache is maintained on the local NetScaler SD-WAN WANOP appliance. When a local user views a video that has already been cached, the appliance can deliver the cached copy at full LAN speed.
After you configure the appliance to cache videos, it caches the videos viewed by your users. You can also use the pre-population option to fetch selected videos from the local video server in anticipation of later use.
The video caching feature uses an intercepting proxy cache to examine all HTTP requests. Requests that meet the requirements listed below are cached. Videos are not served from the cache unless they are evaluated as fresh by the cache engine. Otherwise, they are fetched again for the viewer, and the previously cached version is overwritten.
Latest content guaranteed. Every time a video is viewed, the cache checks the origin server, and if the video has changed, the cached content is discarded and the new content is downloaded.
Caching is now transparent. That is, the IP address of both the client and the server are maintained end-to-end. In earlier releases, the IP address of the NetScaler SD-WAN WANOP appliance was displayed as the source address.
A video is cached when all of the following criteria are met:
The protocol used to stream the video is HTTP. By default, port 80 is configured for video caching. However, if you have configured another port, such as 8080 for a web server, you must specify this port for caching videos.
You have added video sources from which you want to cache videos. By default, YouTube, Vimeo, Youku, Dailymotion, and Metacafe video sources are added to the appliance, but only YouTube and Vimeo are enabled. If you want to cache videos from any of the other default sources, you must enable them. When adding new video sources, you can enable them as you add them.
Besides YouTube, Vimeo, Metacafe, Dailymotion, and Youku, you can specify additional websites, IP addresses, or subnets as video sources. Note that these websites should not have any avoidance mechanisms, such as adding random characters to a URL.
The video must be in one of the recognized video formats and have the one of the following file extensions: .3gp, .avi, .dat, .divx, .dvx, .dv-avi, .flv, .fmv, .h264, .hdmov, .m15, .m1v, .m21, .m2a, .m2v, .m4e .m4v, .m75, .moov, .mov, .movie, .mp21, mp2v, .mp4, .mp4v, .mpe, .mpeg, mpeg4, mpg, mpg2, .mpv, .mts, .ogg, .ogv, .qt, .qtm, .ra, .rm, .ram, .rmd, .rms, rmvb, .rp, rv, .swf, .ts, .vfw, .vob, .webm, .wm, .wma, .wmv, and .wtv.
The video caching feature is supported by the following appliances:
SD-WAN WANOP 600 appliance with 1 Mbps and 2 Mbps bandwidth license models.
SD-WAN WANOP 800 appliance with all bandwidth license models.
SD-WAN WANOP 1000 appliance with Windows Server, with all bandwidth license models.
SD-WAN WANOP 2000 appliance with all the bandwidth license models.
SD-WAN WANOP 2000 appliance with Windows Server, with all bandwidth license models.
SD-WAN WANOP 3000 appliance with all the bandwidth license models.
SD-WAN WANOP VPX and SD-WAN WANOP VPX for Amazon
Video server supported
Video caching feature is supported on Adobe Flash Media Server 4.5 or later. Additionally, any video server that serves videos over HTTP as static links are supported for video caching.
Deployment modes supported
Video caching is supported in inline, inline within VLAN trunk ports, virtual inline, and WCCP deployment modes.
Considerations for using the video caching feature
Following are some points to be aware of when using the video caching feature.
If any of the supported websites change the way they present content, the video caching benefit for those sites might not be achieved until the video caching policy file is updated. For such occasional changes, NetScaler provides an updated video caching policy file. To use it, see Upgrading the Video Caching Policy File.
Some video websites might use different file formats for the same video, depending on the operating system or the browser used to access the video. This might result in a cache miss.
Some video websites, such as YouTube, adapt to the network conditions. The quality of a video can therefore depend on the network conditions at the time it is cached.