Arrangement for load sharing in computer networks

Abstract

The invention relates to an arrangement for load sharing in computer networks and, more exactly, an arrangement for distribution of traffic, for instance via Internet, from clients ( 1 ) to service suppliers who provide services from many servers. The invention makes possible distribution to one of a number of replicated servers. Suitable server is selected for instance on basis of available resources at the interface of the server, or less delay in the transmission. The invention results in better performance and reduced traffic by distribution of the traffic geographically and from a resource point of view. According to the invention, a number of replicated servers ( 5 A- 5 E) belong to an anycast-group and each anycast-group is connected to a domain name server ( 2 ) which has the ability to select one of the replicated servers, so that a router ( 4 ) can establish a connection between the selected server and the service-requesting client computer. Each replicated server ( 5 A- 5 E) can transmit a resource advertisement which contains information about available resources at the server in question, and about the link parameters of the server.

What is claimed is: 
     
       1. A computer implemented system for designating a resource location among a plurality of resource locations, comprising:
 at least one client computer; 
 at least one service supplier responsive to requests of the at least one client computer, the at least one service supplier comprising,
 i. a domain server configured to provide access to the plurality of resource locations in response to a request from the at least one client computer, the plurality of resource locations being replicated servers operably linked to the domain server, a portion of the replicated servers being configured to be responsive to an anycast address protocol, 
 ii. at least one router responsive to the portion of replicated servers, the router having a routing table configured to receive resource advertisements from the portion of replicated servers, the resource advertisements including at least capacity data of each replicated server, the router being operably linked to the domain server for resolving the designation of the resource location among the plurality of resource locations, 
 
 wherein the domain server utilizes the anycast address protocol for accessing the plurality of resource locations, the router table being responsive to the anycast requests of the domain server to designate the resource location for access by the at least one client computer in accordance with the resource advertisements of the table, and 
 wherein a resource advertisement is periodically transmitted from a corresponding replicated server upon a change of a predetermined amount in the capacity data of the corresponding replicated server. 
 
     
     
       2. The computer implemented system of  claim 1 , wherein the at least one router designates the resource location as the replicated server having the most available capacity in accordance with the resource advertisements of the table. 
     
     
       3. The computer implemented system of  claim 1 , wherein the resource advertisement includes link data. 
     
     
       4. The computer implemented system of  claim 3 , wherein the link data includes parameters for indicating a link latency value. 
     
     
       5. The computer implemented system of  claim 1 , wherein the routing table designates the resource location based only on a location of each replicated server. 
     
     
       6. The computer implemented system of  claim 1 , wherein the resource advertisement includes at least one of token bucket depth and token bucket rate. 
     
     
       7. The system of  claim 1 , wherein the replicated servers are arranged in a service hierarchy and respective Private Network Node Interface (PNNI) routing levels are used to identify respective hierarchical levels of the replicated servers. 
     
     
       8. The system of  claim 7 , wherein the at least one router designates the resource location as a replicated server on a lowest possible level in the service hierarchy, a difference in the respective PNNI routing levels of any two replicated servers in the service hierarchy being used as a measure of proximity between the two replicated servers. 
     
     
       9. A method of designating a replicated server among a plurality of replicated servers, comprising:
 receiving, by a domain server, a service request from at least one client computer, the domain server operably linked to the plurality of replicated servers, wherein the replicated servers are accessible using an anycast address protocol; 
 receiving, by at least one router, an anycast service request from the domain server, each router operably linked to the domain server for resolving the designation of the replicated server among the plurality of replicated servers; 
 receiving, by a respective routing table of the at least one router, resource advertisements from the plurality of replicated servers, the resource advertisements including respective capacity data of the plurality of replicated servers; and 
 designating the replicated server among the plurality of replicated servers based on information stored in the respective routing table, 
 wherein a resource advertisement is periodically transmitted from each replicated server upon a change of a predetermined amount in the capacity data of the corresponding replicated server. 
 
     
     
       10. The method of  claim 9 , wherein the at least one router designates the replicated server having the most available capacity in accordance with the information in the respective routing table. 
     
     
       11. The method of  claim 9 , wherein the resource advertisements include link data. 
     
     
       12. The method of  claim 9 , wherein the link data includes parameters indicating a link latency value. 
     
     
       13. The method of  claim 9 , wherein the routing table designates the resource location based only on a location of each replicated server. 
     
     
       14. The method of  claim 9 , wherein the resource advertisement includes at least one of token bucket depth and token bucket rate. 
     
     
       15. The method of  claim 9 , wherein the replicated servers are arranged in a service hierarchy and respective Private Network Node Interface (PNNI) routing levels are used to identify respective hierarchical levels of the replicated servers. 
     
     
       16. The method of  claim 15 , wherein the at least one router designates the resource location as a replicated server on a lowest possible level in the service hierarchy, a difference in the respective PNNI routing levels of any two replicated servers in the service hierarchy being used as a measure of proximity between the two replicated servers. 
     
     
       17. A system for managing resources, comprising:
 a service supplier responsive to requests of a client computer, wherein the service supplier comprises:   a domain server capable of providing access to a plurality of resource locations based at least in part upon a request from the client computer, the plurality of resource locations comprising replicated servers capable of communicating with the domain server, a portion of the replicated servers being configured to be responsive to an anycast address protocol,   a router responsive to the portion of replicated servers, the router comprising a routing table capable of receiving resource advertisements from the portion of replicated servers, the resource advertisements comprising capacity data of each replicated server, the router being capable of communicating with the domain server for resolving designation of the resource location among the plurality of resource locations,
 wherein the domain server is capable of utilizing the anycast address protocol for communicating with the plurality of resource locations, the router table being responsive to the anycast requests of the domain server to designate the resource location for access by the client computer based at least in part upon the resource advertisements of the table, and 
 wherein the resource advertisement is periodically transmitted from a corresponding replicated server upon a change of a predetermined amount in the capacity data of the corresponding replicated server. 
   
     
     
       18. The system according to claim 17, wherein the router is capable of designating the resource location as the replicated server having the most available capacity, based at least in part upon the resource advertisements of the table. 
     
     
       19. The system according to claim 17, wherein the resource advertisement comprises parameters for indicating a link latency value. 
     
     
       20. The system according to claim 17, wherein the routing table is capable of designating the resource location based only on a location of each replicated server. 
     
     
       21. The system according to claim 17, wherein the resource advertisement comprises a token bucket depth. 
     
     
       22. The system according to claim 17, wherein the resource advertisement comprises a token bucket rate. 
     
     
       23. An article comprising a non-transitory storage medium having stored thereon instructions, which, if executed, result in:
 receiving a service request from at least one client computer, wherein a domain server is capable of communicating with the plurality of replicated servers, and wherein the replicated servers are capable of being accessed utilizing an anycast address protocol;   receiving resource advertisements from the plurality of replicated servers, the resource advertisements comprising respective capacity data of the plurality of replicated servers;   designating the replicated server among the plurality of replicated servers based at least in part on information stored in a respective routing table; and   periodically transmitting a resource advertisement from each replicated server based at least in part upon a change of a predetermined amount in the capacity data of the corresponding replicated server.   
     
     
       24. The article according to claim 23, further comprising receiving an anycast service request from the domain server, each router being capable of coupling to the domain server for resolving the designation of the replicated server among the plurality of replicated servers. 
     
     
       25. The article according to claim 23, further comprising, designating the replicated server having the most available capacity based at least in part upon the information in the respective routing table, at least in part by the at least one router. 
     
     
       26. The article according to claim 23, wherein the resource advertisements comprise link data. 
     
     
       27. The article according to claim 26, wherein the link data comprises parameters indicating a link latency value. 
     
     
       28. The article according to claim 23, further comprising designating the resource location based at least in part upon on a location of each replicated server, at least in part by the routing table. 
     
     
       29. The article according to claim 23, wherein the resource advertisement comprises a token bucket depth. 
     
     
       30. The article according to claim 23, wherein the resource advertisement comprises a token bucket rate. 
     
     
       31. The article according to claim 23, further comprising arranging the replicated servers in a service hierarchy. 
     
     
       32. A method, comprising:
 receiving a service request from at least one client computer, wherein a domain server is capable of communicating with the plurality of replicated servers, and wherein the replicated servers are capable of being accessed utilizing an anycast address protocol;   receiving resource advertisements from the plurality of replicated servers, the resource advertisements comprising respective capacity data of the plurality of replicated servers;   designating the replicated server among the plurality of replicated servers based at least in part on information stored in a respective routing table of a router; and   periodically transmitting a resource advertisement from each replicated server based at least in part upon a change of a predetermined amount in the capacity data of the corresponding replicated server.   
     
     
       33. The method according to claim 32, further comprising receiving an anycast service request from the domain server, each router being capable of coupling to the domain server for resolving the designation of the replicated server among the plurality of replicated servers. 
     
     
       34. The method according to claim 32, further comprising, designating the replicated server having the most available capacity based at least in part upon the information in the respective routing table, at least in part by the at least one router. 
     
     
       35. The method according to claim 32, wherein the resource advertisements comprise link data. 
     
     
       36. The method according to claim 35, wherein the link data comprises parameters indicating a link latency value. 
     
     
       37. The method according to claim 32, further comprising designating the resource location based at least in, part upon on a location of each replicated server, at least in part by the routing table. 
     
     
       38. The method according to claim 32, wherein the resource advertisement comprises a token bucket depth. 
     
     
       39. The method according to claim 32, wherein the resource advertisement comprises a token bucket rate. 
     
     
       40. The method according to claim 32, further comprising arranging the replicated servers in a service hierarchy.