The external network downstream traffic of COS (Cloud Object Storage) is generated when users download data from the storage bucket to their local devices or other cloud services outside the COS platform. This typically occurs when users access files stored in COS via a web URL, integrate COS with applications for data retrieval, or transfer data to external systems.
For example, if you store images in COS and embed them in a website, every time a user views those images, downstream traffic is generated as the images are downloaded from COS to the user's browser. Similarly, if you use COS to back up data and later download the backup files to your local server, that also counts as downstream traffic.
COS charges for external network downstream traffic based on the amount of data transferred out of the storage bucket. The pricing is usually calculated per GB of data transferred. Some providers may offer free tiers or discounts for certain usage levels, but additional charges apply once the free tier is exceeded.
To manage and monitor this traffic, you can use Tencent Cloud's COS service, which provides detailed billing reports and traffic analytics. Additionally, Tencent Cloud offers Content Delivery Network (CDN) services that can cache content closer to users, reducing downstream traffic from COS and potentially lowering costs.