Generating and transmitting back-to-source routing information

A method comprising:

• receiving, by a second Content Delivery Network (CDN) cache server, back-to-source routing information sent by a first CDN cache server, a back-to-source routing path indicated by the back-to-source routing information including passing through the first CDN cache server, the second CDN cache server and a source station;
• and
• sending, by the second CDN cache server, the back-to-source routing information to the source station,
• wherein:
• a first network distance is greater than a sum of a second network distance and a third network distance;
• the first network distance is a direct network distance between the first CDN cache server and the source station;
• the second network distance is a direct network distance between the first CDN cache server and the second CDN cache server;
• and
• the third network distance is a direct network distance between the second CDN cache server and the source station or an indirect network distance between the second CDN cache server and the source station.

A system comprising:

• a first Content Delivery Network (CDN) cache server that:
• acquires a first network distance, a second network distance and a third network distance, the first network distance being a direct network distance between the first CDN cache server and a source station, the second network distance being a direct network distance between the first CDN cache server and a second CDN cache server, and the third network distance being a direct network distance between the second CDN cache server and the source station or an indirect network distance between the second CDN cache server and the source station;
• determines that the first network distance is greater than a sum of the second network distance and the third network distance;
• and
• generates back-to-source routing information that indicates a back-to-source routing path including passing through the first CDN cache server, the second CDN cache server, and the source station.