Method and system for tiered distribution in a content delivery network

Abstract

A tiered distribution service is provided in a content delivery network (CDN) having a set of surrogate origin (namely, “edge”) servers organized into regions and that provide content delivery on behalf of participating content providers, wherein a given content provider operates an origin server. According to the invention, a cache hierarchy is established in the CDN comprising a given edge server region and either (a) a single parent region, or (b) a subset of the edge server regions. In response to a determination that a given object request cannot be serviced in the given edge region, instead of contacting the origin server, the request is provided to either the single parent region or to a given one of the subset of edge server regions for handling, preferably as a function of metadata associated with the given object request. The given object request is then serviced, if possible, by a given CDN server in either the single parent region or the given subset region. The original request is only forwarded on to the origin server if the request cannot be serviced by an intermediate node.

1 . A method operative in a content delivery network (CDN) having a set of servers organized into regions and that provide content delivery on behalf of participating content providers, comprising:
 establishing a cache hierarchy in the CDN for each of first and second content providers that are distinct from one another and distinct from a service provider that operates the content delivery network, each cache hierarchy comprising a CDN content server and one of: (a) a single parent region located in a selected location, and (b) a subset of parent regions located in a set of selected locations, wherein the selected locations are variable such that a cache hierarchy in the CDN for the first content provider differs from a cache hierarchy in the CDN for the second content provider;   in response to a first determination that a first object request cannot be serviced in a CDN content server, directing a first new request to the cache hierarchy associated with the first content provider instead of an origin server associated with the first content provider; and   in response to a second determination that a second object request cannot be serviced in a CDN content server, directing a second new request to the cache hierarchy associated with the second content provider instead of an origin server associated with the second content provider.   
   
   
       2 . The method as described in  claim 1  wherein the respective first new request or the second new request is directed based on content provider-specific metadata associated with the object request. 
   
   
       3 . The method as described in  claim 1  further including, in response to the first new request, receiving a response from the cache hierarchy in the CDN for the first content provider, where the response includes the content object associated with the first object request and time-to-live (TTL) information for the content object. 
   
   
       4 . The method as described in  claim 1  further including, in response to the second new request, receiving a response from the cache hierarchy in the CDN for the second content provider, where the response includes a content object associated with the second object request and time-to-live (TTL) information for the content object. 
   
   
       5 . The method as described in  claim 4  wherein the single parent region is associated with only the first content provider and the selected location is nearby the origin server associated with the first content provider. 
   
   
       6 . The method as described in  claim 4  wherein the single parent region is associated with only the first content provider and the selected location is co-located with the origin server associated with the first content provider.