September 24, 2018
Netflix® has become the largest online entertainment company. The Economist (January 28, 2018) estimates that over 20% of the world's downstream traffic is driven by Netflix, making it the most bandwidth-hungry application on the Internet. Netflix is also very dependent on the speed of network connections, since the download speed determines the quality of the video delivered to the end customers.
Netflix servers around the world "stream" videos to end users using ABR (Adaptative Bit Rate) technology, which means that, instead of downloading the whole video file, Netflix players download the video in many small pieces of a few seconds each, called "chunks". Players measure the speed at which chunks are downloaded, and when high speeds are measured, they ask for larger chunks with higher video resolution and quality, but when low speeds are detected, they request smaller chunks with lower resolution and quality.
For downloading the individual video chunks, Netflix uses the TCP protocol. TCP, like all transport protocols, has to determine at what speed the servers should send the video chunks. Too fast, and intermediate nodes will be congested, so some data packets will be lost and retransmitted, resulting in a slower download. Too slow, and network capacity will be under-utilized. TCP has to learn what is the optimum speed at which each server should send, which is hard because there may be many hops from the Netflix servers to the Netflix players, and each hop may have changing capacity. The end result is that TCP often has to be conservative and will tend to send data slower than what the network could reach, especially when there are wireless hops (like WiFi or LTE), which are especially variable.
At bequant we have developed and patented a TCP protocol especially designed for wireless networks and for networks with packet losses. With the most advanced congestion detection and avoidance algorithms, it reduces the under-utilization of network capacity of TCP, increasing the speed of the Internet TCP traffic by up to 100%. We have then developed a scalable and reliable transparent proxy, the BQN BTA (Bequant TCP Acceleration), that ISPs and hotspots can place in their networks to accelerate the TCP traffic flowing through it.
We decided to take the challenge and measure, in real live networks in some of our customers, the impact of the BQN BTA product on Netflix traffic. In these networks all the TCP traffic is going through a BQN BTA node to accelerate it, and we have measured the average download speed of Netflix chunks, with and without our acceleration. Being in the path for all these downloads, our product can accurately measure the speed of each chunk download, and leave a small percentage of downloads without acceleration to measure as reference.
Several weeks of traffic were analyzed, between March and June 2018 to get metrics under a variety of network conditions. Also, networks with different access technologies were selected, such as a fiber operator (ISP Fiber), LTE mobile operators (MNO 4G), Wireless ISPs (WISP) and fixed LTE operator (ISP 4G). And the results are more than compelling, with consistent double-digit enhancement across all network types:
It can be seen that the improvement in speed obtained in some of these measurements (e.g.WISP A, we cannot reveal names), meant that the Netflix service went from not being viable to a speed at which a medium resolution was possible. In some others, it meant that the mean resolution and quality of Netflix videos increased significantly. With this, the end users of these networks experienced a substantial improvement in the viewing quality of Netflix, the networks operators benefited from a higher customer satisfaction and we helped Netflix deliver a better experience.