Global load balancing across mirrored data centers

Abstract

An intelligent traffic redirection system that performs global load balancing can be used in any situation where an end-user requires access to a replicated resource. The method directs end-users to the appropriate replica so that the route to the replica is good from a network standpoint and the replica is not overloaded. The technique preferably uses a Domain Name Service (DNS) to provide IP addresses for the appropriate replica. The most common use is to direct traffic to a mirrored web site.

1 . Apparatus to generate a network map, the network map for use in determining which of a set of mirror sites should receive a request to a domain that is replicated at the set of minor sites, comprising:
 a processor;   computer memory holding computer program instructions that when executed by the processor perform a method, the method comprising:   generating a score for each minor site, where the score is a function of a time-weighted average of latency modified by a penalty factor that is a function of a time-weighted average of packet loss, the latency and packet loss being measured against a set of proxy points in a network;   identifying which minor site provides a given performance metric based on the score; and   associating a name server address with the identified minor site to generate the network map.   
   
   
       2 . The apparatus as described in  claim 1  wherein the set of proxy points identify locations in the Internet where given trace routes intersect. 
   
   
       3 . The apparatus as described in  claim 2  wherein the given trace routes are associated with the set of minor sites. 
   
   
       4 . The apparatus as described in  claim 1  further including a name server process. 
   
   
       5 . The apparatus as described in  claim 4  wherein the method further includes receiving a query at the name server process, and using the network map to enable the name server process to generate a response to the query.