Tuesday, September 30, 2014

Overview of Netflix architecture

In order to observe the basic service behavior, Lets create a new user account, login into the Netflix website and play a movie. Start monitoring the traffic during all of this activity and record the host names of the servers involved in the process and then perform DNS resolutions to collect the canonical names (CNAMEs) and IP addresses of all the server names that the browser have contacted. We also perform WHOIS lookups for the IP addresses to find out their owners. Table
I summarizes the most relevant hostnames and their owners. Fig. shows the basic architecture for Netflix video streaming platform.


It consists of four key components: Netflix data center, Amazon cloud, CDNs and players for Netflix

Data Centers. Our analysis reveals that Netflix uses its own IP address space for the hostname
www.netflix.com. This server primarily handles two key functions: (a) registration of new user accounts and capture of payment information (credit card or Paypal account), and (b) redirect users to movies.netflix.com or signup.netflix.com based on whether the user is logged in or not respectively. This server does not interact with the client during the movie playback, which is consistent with the
recent presentation from Netflix team [9]

Amazon Cloud. Except for www.netflix.com which is hosted by Netflix, most of the other Netflix
servers such as agmoviecontrol.netflix.com and movies.netflix.com are served off the Amazon
cloud [10]. [9] indicates that Netflix uses various Amazon cloud services, ranging from EC2 and S3, to SDB and VPC. Key functions, such as content ingestion, log recording/analysis, DRM, CDN routing, user sign-in, and mobile device support, are all done in Amazon cloud.

Content Distribution Networks (CDNs). Netflix employs multiple CDNs to deliver the video content to end users. The encoded and DRM protected videos are sourced in Amazon
cloud and copied to CDNs. Netflix employs three CDNs: Akamai, LimeLight, and Level-3. For the same video with the  same quality level, the same encoded content is delivered from all three CDNs. In Section II-D we study the Netflix strategy used to select these CDNs to serve videos.

Netflix Players. Netflix uses Silverlight to download, decode and play Netflix movies on desktop web browsers. The run-time environment for Silverlight is available as a plug-in for most web browsers. There are also players for mobile phones and other devices such as Wii, Roku, etc.

Netflix uses the DASH (Dynamic Streaming over HTTP) protocol for streaming. In DASH, each video is encoded at several different quality levels, and is divided into small ‘chunks’- video segments of no more than a few seconds in length. The client requests one video chunk at a time via HTTP. With each download, it measures the received bandwidth and runs a rate
determination algorithm to determine the quality of the next chunk to request. DASH allows the player to freely switch between different quality levels at the chunk boundaries.

Ref: Unreeling Netflix: Understanding and Improving Multi-CDN Movie Delivery IEEE paper

1 comment: