This topic describes the major performance indicators that are used to evaluate the performance of content delivery before and after a website is connected to Alibaba Cloud CDN. This topic also describes the benefits of Alibaba Cloud CDN.

Using Alibaba Cloud CDN can offload the workloads on origins and accelerate content delivery. The performance indicators that are used to evaluate the performance of content delivery include common indicators and scenario-specific indicators. By referencing these indicators, you can learn how Alibaba Cloud CDN accelerates content delivery and how Alibaba Cloud CDN is applied to your services. This helps you make adjustments and business decisions.

Common performance indicators

You can use the following indicators to measure the performance of your website before and after the website is connected to Alibaba Cloud CDN. The indicators include but are not limited to the following:
  • Latency: shows the total amount of time it takes for a server to receive a request from a client and then return a response to the client. The lower the latency, the higher the performance.
  • Downloading speed: data transmission rate, which shows how quickly a client can download data from a server. The higher the downloading speed, the higher the performance.
  • Website content loading speed: shows how quickly a Web page can be loaded. The faster the loading speed, the higher the performance.
  • Packet loss rate: shows the number of packets lost during data transmission to the total number of packets.
  • Back-to-origin rate: includes the back-to-origin request rate and back-to-origin data transfer rate.
    • Back-to-origin request rate: shows the number of requests forwarded back to the origin to the total number of requests. Edge nodes forward requests back to the origin when the requested content is not found, has expired, or cannot be cached. The lower the rate, the higher the performance.
    • Back-to-origin data transfer rate: shows the amount of data forwarded back to the origin to the total amount of request data. The following formula is used to calculate this rate: Back-to-origin data transfer rate = Amount of back-to-origin data/Amount of user request data. The lower the rate, the higher the performance.
  • Cache hit rate: shows the number of times that the content on a cache node is hit to the total number of visits made by a client to the cache node. The higher the cache hit rate, the higher the performance.
Note The back-to-origin rate and cache hit rate are indicators used to measure the performance of your website after the website is connected to Alibaba Cloud CDN. If you have not connected your website to Alibaba Cloud CDN, the back-to-origin request rate is 100% and the cache hit rate is 0.
Typically, after you connect your website to Alibaba Cloud CDN, the network latency, packet loss rate, and back-to-origin rate all go down. The download speed, website content loading speed, and cache hit rate rise up. The actual performance of the content delivery acceleration service provided by Alibaba Cloud CDN may vary depending on the scenario and type of your businesses. Therefore, we only provide these common indicators for you to measure the performance of your website.
Alibaba Cloud CDN also provides multiple performance indicators for different scenarios. You can use the following indicators to measure the performance of your website in a specific scenario:

Small file downloading and uploading indicators

Small files refer to HTML, JS, JPG, and CSS Web content. The delivery of these types of content requires extremely low latency. It is difficult for slow-loading websites to retain users and this may cause great loss in sales.

The indicators that are used to measure the content loading latency include connection time, time to first byte (TTFB), and downloading time. Among these indicators, TTFB is the core indicator.
  • Connection time: shows the amount of time that it takes to establish a TCP connection to the resolved IP address. The connection time can help you learn the number of available CDN nodes and their capabilities for content delivery.
  • TTFB: shows the total amount of time that it takes for a server to receive the first request sent from a client and then return a response to the client. This indicator is used to measure the performance of the algorithms and applications that CDN nodes use.
    • For content uploading, TTFB includes the DNS resolution time, TCP connection time, SSL handshake time, request delivery time, and response reception time.Upload
    • For content downloading, TTFB includes DNS resolution time, TCP connection time, SSL handshake time, request delivery time, response reception time, and downloading time.Download
    Note A newly purchased domain may cost longer time than other domains in DNS resolution. This is irrelevant to the cache retrieval time.

Alibaba Cloud CDN provides a configuration guide for accelerating small file delivery. For more information, see Images and small files.

Large file downloading indicators

A large file is a file that is larger than 20 MB. Downloading speed and total downloading time are the core indicators used to measure the performance of large file downloading.

Alibaba Cloud CDN provides a configuration guide for accelerating large file downloading. For more information, see Large file download.

VOD service indicators

The types of media files used in video on-demand (VOD) services include FLV, MP4, WMV, and MKV files. Initial loading and stalling rate are the core indicators used to measure the performance of VOD services.
  • Initial loading: shows the total amount of time that it takes to complete loading the first frame of a stream. The DNS resolution time, connection time, and TTFB all have impacts on initial loading.
  • Stalling rate: stalling events may occur when a video or audio stream is played or a resource is loaded. The stalling rate refers to the rate of reviewers that have stalling events among every 100 reviewers. The lower the stalling rate, the higher the performance.

Alibaba Cloud CDN provides a configuration guide for accelerating VOD services. For more information, see VOD.

Live streaming service indicators

Same as VOD services, the core indicators used to measure the performance of live streaming services are initial loading and stalling rate. For more information, see What is ApsaraVideo Live.

Benefits of Alibaba Cloud CDN

Alibaba Cloud CDN has more than 2,800 nodes deployed across the world. The throughput of the entire content delivery network is up to 130 Tbit/s. Alibaba Cloud CDN is fast, stable, cost-effective, and easy-to-use. For more information, see Benefits.