This topic describes how to select an appropriate clean bandwidth when you purchase an Anti-DDoS Pro or Anti-DDoS Premium instance.

You can select an appropriate clean bandwidth based on the daily inbound and outbound traffic peaks of all existing and future services that you plan to run on the instance. Make sure that the clean bandwidth of the instance is greater than the highest peak bandwidth of the inbound and outbound traffic.

Note In most cases, the peak of the outbound traffic is greater than that the of inbound traffic.

You can estimate the actual bandwidth based on the traffic statistics collected in the Elastic Compute Service (ECS) console or by using other monitoring tools on your origin server. The traffic described here refers to the normal traffic generated by your services.

Assume that you connect a website to an Anti-DDoS Pro or Anti-DDoS Premium instance for protection. If no attacks are launched at your website, Anti-DDoS Pro or Anti-DDoS Premium only needs to forward user traffic to the origin server. However, if your website is under attack, Anti-DDoS Pro or Anti-DDoS Premium blocks malicious traffic and forwards only user traffic to the origin server. Therefore, the ECS console only displays statistics about inbound and outbound user traffic flows through the origin server. If your services are deployed on multiple origin servers, you must calculate the sum of the traffic volumes required by all origin servers.

Clean bandwidth

Assume that you want to connect three websites to an Anti-DDoS Pro or Anti-DDoS Premium instance. The peak of the outbound user traffic on each website is 50 Mbit/s or lower. The total bandwidth required by the three websites is 150 Mbit/s or lower. In this case, set the clean bandwidth of the instance that you want to purchase to a value greater than 150 Mbit/s.