Last update：2022-03-30 15:06:58
When the customer uses the CDNetworks CDN service, the CDN PoPs will act as an origin to respond to user requests, and also as a user to interact with the origin server. CDNetworks supports multiple back-to-origin (Hereafter written as BtO) strategies including:
The BtO configuration is the primary and necessary configuration when using all the CDNetworks acceleration products. Customers will adopt different BtO policies according to their business characteristics.
Customers provides the origin domain name. CDNetworks performs DNS resolution and the CDN server will go back to the origin with the resolved IP.
This BtO strategy is applicable to customers whose origin IP addresses are unstable and change frequently.
Customers provide their origin IP, and CDNetworks binds the acceleration domain name to the fixed origin IP.
This strategy is recommended when customer origin’s IP address is stable and do not change frequently.
Alternate BtO supports using different domain names and ports for CDN and BtO requests. For example: use domain A and port A for CDN requests, but use domain B and port B for BtO requests.
Some customers do not use their own domains or regular ports for BtO requests. For example, the customer is using CDNetworks’ or AWS’ cloud origin, and the origin domain is provided by CDNetworks or AWS, so their domain/port for CDN requests will be different from the BtO domain/port. We recommend Alternate BtO solution for these customers.
CDNetworks maintains the mapping between the user IP and the origin server IP to ensure that requests with the same user IP are resolved to the same origin server.
If a user had sent a BtO request before, some customer would hope that the next BtO request sent by the same user will be resolved to the same origin server (to keep the login status for the user). CDNetworks recommends the BtO by user IP strategy for these customers.
When a customer’s origins are dispersed in different ISP networks, BtO by ISP guarantees that the BtO request go back to the origin of the corresponding ISP. By this way, the cross-network BtO request is avoided, and the cross-network time is saved.
It is recommended when a customer has multiple origins deployed in different ISP networks.
With User IP Forwarding, CDNetworks will add the IP address of the end user in the HTTP header “Cdn-Src-IP” or “X-Forward-For” when sending the BtO request to the origin.
CDNetworks also supports other custom HTTP headers when requested by customers. In this way, customers can collect the user IP information.
It is used when customer needs to collect user IP information.
If the BtO domain or IP changes, customer needs to timely inform CDNetworks to ensure the mapping between the acceleration domain/IP and origin has been updated. Otherwise, it will affect the BtO requests and ultimately affect the service of customers.