Content request routing and load balancing for content distribution networks

Abstract

A content distribution mechanism that distributes content of a content provider at various sites across a network and selects the site that is nearest a content requestor using an anycast address that resides at each of the sites. The sites are configured as nodes (or clusters) and each node includes a content server and a DNS server. The DNS servers are so associated with the content servers at their respective nodes as to resolve the name of the content provider to the IP address of the content servers at the nodes. The DNS servers each are assigned the anycast address in addition to a unique address, and the anycast address is advertised to the network (in particular, the network routing infrastructure) using Border Gateway Protocol (BGP). Node selection occurs when the network routing infrastructure selects a shortest path to the anycast address during DNS name resolution.

What is claimed is:  
     
         1 . A method of content delivery in a network, comprising: 
 associating devices in a Domain Name System (DNS) with content server systems located in the network, the content server systems maintaining and serving content of a content provider, each DNS device configured to resolve the name of the content provider to an address for the content server system with which such DNS device is associated; and    assigning to the DNS devices a common address, the common address being usable to resolve the name of the content provider such that a request for content of the content provider by a content requestor is sent to the content server system nearest the content requestor.    
     
     
         2 . The method of  claim 1 , wherein the common address is an anycast address.  
     
     
         3 . The method of  claim 2 , wherein routing information associated with the anycast address is advertised over the network by the DNS devices in accordance with the Border Gateway Protocol (BGP).  
     
     
         4 . The method of  claim 1 , wherein the content server systems are geographically distributed across the network.  
     
     
         5 . The method of  claim 1 , wherein the DNS devices are collocated with the content server systems with which the DNS devices are associated.  
     
     
         6 . The method of  claim 1 , wherein each content server system and associated DNS device are located in a different Internet Service Provider Point of Presence.  
     
     
         7 . The method of  claim 1 , wherein each content server system and associated DNS device is located at or near an entry point of the network.  
     
     
         8 . The method of  claim 1 , where the content server systems comprise cache systems that cache content of the content provider.  
     
     
         9 . The method of  claim 8 , wherein at least one of the cache systems comprises at least two cache servers connected in a cluster, and wherein the at least two cache servers are coupled to a switch usable to select from among the at least two cache servers based on a selection policy.  
     
     
         10 . A computer program product residing on a computer-readable medium for managing a content delivery network, the computer program product comprising instructions causing a computer to: 
 maintain content server systems at different locations in the network to store content of a content provider and serve content to a content requester;    configure Domain Name System (DNS) devices to resolve a name of the content provider to an address for a corresponding one of the content server systems; and    assign to each of the DNS devices a common address, the common address being usable to allow a content request intended for the content provider to be sent to the content server system nearest the content requestor.    
     
     
         11 . A content distribution system comprising: 
 content distribution nodes connected to a content provider, a content provider Domain Name System (DNS) server and a content requestor DNS server via the Internet, each content distribution node including a DNS server coupled to and associated with a content server system, the content server system operating to store content originating with the content provider and serve content to a content requester, and each DNS server being assigned an address common to all of the DNS servers in the content distribution nodes;    the common address being provided by the content provider DNS server to the content requestor DNS server in response to a DNS request from the content requestor DNS server, thereby enabling the content requestor DNS server to use the Internet to select a path to the content distribution node nearest the content requestor and forward the DNS request to the selected node; and    the DNS server in the selected node being configured to resolve the name of the content provider in the DNS request to an IP address of the associated content server system and cause the IP address to be returned to the content requester.