Background Information

In the industry, the acceleration performance of a CDN is generally evaluated based on the performance metrics described in the following parts. You can observe the metric values before and after your website is accelerated by eSurfing Cloud CDN to determine the acceleration effect.

Common Metrics

In most cases, the following metrics show significant performance improvements after eSurfing Cloud CDN is used. However, factors such as the business scenario, business type, origin server performance, and content popularity affect the effectiveness of the metrics. For example, the acceleration performance for websites, downloads, and video-on-demand (VOD) streaming vary based on the content characteristics. Therefore, this section provides only qualitative metrics for your references.

The following figure shows the relationships among major metrics.

The following table describes the common metrics in the perspectives of CDN users and third-party network speed test service providers. The general CDN performance metrics are not limited to these metrics.

Type	Metrics	Description
Major evaluation metric	Overall performance	The average response time. The smaller the metric value is, the shorter the response time is.
Major evaluation metric	Availability	The access success rate. The higher the metric value is, the higher the availability is.
Network metrics	DNS resolution time	The amount of time it takes for the domain name system to resolve the specified domain name to the corresponding IP addresses.
Network metrics	TCP connection time	The amount of time it takes for a browser or client to establish a TCP/IP connection to a web server.
Network metrics	SSL handshake time (on demand)	The amount of time it takes for a browser or client to establish a Security Sockets Layer (SSL) connection to a web server.
Network metrics	Time to first packet	The amount of time that elapses from the point in time when an HTTP request is sent from a browser or client to the point in time when the browser or client receives the first data packet returned from the web server.
Network metrics	Content download time	The amount of time that elapses from the point in time when the browser or client receives the first data packet returned from the web server to the point in time when all content of the page is received. This metric is used to monitor the content delivery quality on a page.
CDN platform metrics	Back-to-origin rate	The back-to-origin rate is classified into the back-to-origin request ratio and the back-to-origin traffic ratio. 1.Back-to-origin request ratio: Refers to the percentage of requests for resources that are not cached, have expired, or cannot be cached on CDN points of presence (POPs) to the total requests. Note: For domain names for which the object chunking feature is enabled, the number of back-to-origin requests sent by CDN POPs may be greater than the number of CDN access requests sent by users. This is because CDN retrieves data from the origin server in chunks while no chunking is performed when user requests are sent to access CDN. In such a case, the back-to-origin request ratio metric cannot be used for reference. 2.Back-to-origin traffic ratio: Back-to-origin traffic refers to the amount of traffic that is generated when CDN POPs send back-to-origin requests to retrieve content from origin servers. Back-to-origin traffic ratio = Back-to-origin traffic amount/User request traffic amount. A lower back-to-origin traffic ratio indicates better performance.
CDN platform metrics	Cache hit ratio	The cache hit ratio is classified into the traffic hit ratio and the request hit ratio. A lower CDN cache hit ratio leads to higher workloads on the origin server, thus reducing the static content access efficiency. Calculation method: Traffic hit ratio = 1 - Back-to-origin traffic amount/Total traffic amount (data is collected every 5 minutes) Request hit ratio = 1 - Number of back-to-origin requests/Total number of requests (data is collected every 5 minutes)

Business-specific Metrics

The following table describes the three major CDN acceleration scenarios and the key metrics that you need to pay attention to.

Scenario	Content Accelerated	Metrics
Static small file delivery	Static content such as images, HTML content, CSS content, and JavaScript content	1. Time to first packet 2. Content download time 3. Service availability
Large file download	Large file downloads such as game software downloads, mobile phone ROM updates, application updates, and file downloads from online storage	1. Download speed 2. Total download time 3. Service availability
Audio and video on demand streaming	Audio and video files including but not limited to MP3 files, WMA files, MP4 files, FLV files, HLS files, and large telesync files	1. First meaningful paint 2. Stalling ratio 3. Service availability or success rate

Use Case

The most common method of testing the network speed in the industry is using a third-party network speed test service provider. In this use case, the service provider is Bonree. The test objects are the origin server of a customer and an eSurfing Cloud CDN domain name whose accelerated region is Global.

Performance Overview
Trend Charts
Statistics

Note: The average DNS resolution time of the origin server is 0. This is because the IP address of the origin server is directly accessed and no DNS resolution is required.

Details

In the following example, the acceleration performance is evaluated based on the metric values collected at the first five monitoring points. The values in the following table show that with eSurfing Cloud CDN, the TCP connection time, time to first packet, and overall speed are greatly optimized.

Content Delivery Network

Performance Metrics