An interesting factor in Netflix (and presumably other streaming video) is that they will scale their display resolution based on available bandwidth. This can make bandwidth planning projections murky. For example, from the “Your Account > My Profile > Playback settings” menu item for my Netflix account, there are the following options:
"• Auto • Low (basic video quality, up to 0.3 GB per hour) • Medium (standard video quality, up to 0.7 GB per hour) • High (best video quality, up to 3 GB per hour for HD, 7 GB per hour for Ultra HD)” Auto is the default, and the range from 0.3 GB per hour to 7 GB per hour is a factor of about 23. SO, if most of my users are currently getting “Medium” quality at peak demand times, I could double or quadruple my available bandwidth, and, even if user demand were completely unchanged, all the existing Netflix flows could expand to soak up all of the bandwidth increase. As a rule of thumb for planning, we been assuming “bandwidth demand will double about every year and a half to two years.” In fact, however, Netflix demand can scale up by an order of magnitude with absolutely no change in user behavior. (Presently, we are small and constrained enough that we run an Allot NetEnforcer “packet shaper” at our edge, and streaming video gets a lower priority than general HTML traffic. Even so, during evening prime use periods, Netflix and other streaming video are generally 50% or more of our total inbound traffic.) Steve Bohrer Network Admin, ITS Bard College at Simon's Rock 413-528-7645 ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
