The web can’t handle video, goes the common refrain. For example, Comcast estimates that if people wanted to watch the television content they watch on its pay TV service using the web, each home would consume 648 gigabytes per month. But we’re not nearing some technical tipping point where Netflix, YouTube, Hulu or even pay TV’s on-demand applications are about to break the web.
No, it’s worse. We’re at the point where the web giants, ISPs, backbone providers and content companies are all trying to make their own set of rational decisions about delivering video to avoid having their servers or network assets sit idle while also trying to avoid over-investment. And as a result, consumers are stuck in the middle with no way to know what’s wrong or who’s at fault when their online video stream sucks. So whether it’s a peering battle between Verizon and Cogent that causes a poor Netflix experience or an inability to get a high quality YouTube stream at lunchtime, the consumer experience can sometimes feel like an afterthought.
The problem is that video delivery on the web is fragmented. A Netflix video starts out in Amazon’s cloud but might be delivered via Level 3, Akamai or Cogent to an ISP’s network, or it may be cached at an ISP’s data center or on a Netflix Open Connect box. Once the movie stream is at the last mile, it must traverse an ISP before hitting your home and what may be a flakey Wi-Fi network or merely a congested pipe to the house could cause further problems.
There are multiple points of failure. And finally, a report out Monday from Sandvine makes those many points of failure clear. Sandvine, which makes deep packet inspection gear for ISPs, has spent years tracking traffic and internet trends, but with this report decided to tackle the opaque world of peering and interconnects. The goal is show where the web is failing and why.
The why is pretty easy as it turns out — it’s business. Sometimes problems arise because a content company doesn’t have enough servers to meet the simultaneous demand for content, something Sandvine says happens to YouTube during the lunchtime rush (see chart).
At others, it’s problems caused by congested ports where the middle mile provider like Cogent or Level 3 meets an ISPs’ network. The report tries to explain how the internet works and where those points of interconnections are, while also detailing some technical truths that illustrate how it’s not always the ISP that’s behaving badly when it comes to network congestion.
For example, the report explains how companies like Netflix or Google can save on their content serving costs by delivering their packets in a big burst. But that bursting behavior tends to drive the last mile network to operate at its peak, causing problems for latency sensitive packets such as VoIP and driving up the peak-driven network capital cost. From the report:
Streaming servers are more efficient when they do less context-switching. This in turn incents a content-provider (either through their hosting provider or their CDN) to burst towards the user and then switch to another user. This ‘pulse-width-modulation’ bandwidth reduces context switches on the server, and causes no additional bandwidth to be served from the hosting facility. However, when the other end of the stream reaches the consumer, these bursts can cause considerable additional cost to the access provider.”
The report also accuses the sites that use adaptive bit rate streaming, like Netflix or Hulu, of degrading the performance of other traffic on the user’s network by “pushing aside” non-adaptive content such as gaming, VoIP, and HTTP. The conclusion is that each player on the network is being selfish at the cost of a quality internet experience for all.
Don Bowman, the CTO at Sandvine recommends that the solution to this selfishness isn’t regulation, but transparency. He would like to see data on cost and quality published at every interconnection point. This helps consumers and regulators know where to place the blame and might incent all players to act if not, altruistically, at least more fairly. The secrecy around peering arrangements and the many conflicts of interests within the players and between them create the perfect opportunity for speculation and accusation, but little chance for constructive change.