Resolver caching of a shortest path to a multihomed server as determined by a router

• US 20070014241A1
• Filed: 07/14/2005
• Published: 01/18/2007
• Est. Priority Date: 07/14/2005
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Vallabhaneni, Vasu, Banerjee, Dwip, Vo, Patrick
• Application Number:
  US11/181,416
• Publication Number:
  US 20070014241A1
• Time in Patent Office: Days
• US Class Current: 370/238
• CPC Class Codes: H04L 45/42 Centralised routing
• CPC Class Codes: H04L 61/4511 using domain name system [DNS]
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1038 Load balancing arrangements to avoid a single path through a load balancer

Abstract

A resolver queries a DNS server for any network addresses associated with the particular domain name. If the resolver detects a response for the DNS server with multiple network addresses for a particular domain name, then the resolver creates and sends a shortest path query to at least one router enabled to receive and respond to shortest path queries. The shortest path query indicates at least one source address and the multiple destination addresses returned by the DNS server for the particular domain name. The router detects a separate length for each path accessible between each source address and each of the multiple destination addresses. The router then orders the destination addresses from shortest path to longest path and returns the ordered destination addresses to the requesting resolver. The resolver caches the ordered network addresses in the local cache in association with the particular domain name, such that for future requests for the particular domain name, the resolver retrieves from local cache the shortest path network address as ordered by the router. In addition, the resolver, responsive to receiving the ordered destination addresses, selects the shortest path network address for a response to an application requesting the resolution of the particular domain name.

Claims

1. A system for caching a shortest path from a client system to a multihomed server, comprising:

a resolver for querying a domain name server for any network addresses associated with a particular domain name;

said resolver, responsive to detecting said domain name server return a plurality of network addresses responsive to said query for said particular domain name, for sending a shortest path query to at least one router, wherein said shortest path query specifies at least one source addresses and said plurality of network addresses;

said router for detecting a separate length for each path accessible between said at least one source address and each of said plurality of network address;

said router for ordering said plurality of network addresses to indicate a shortest path to a longest path and sending said ordered plurality of network addresses to said resolver; and

said resolver for caching said ordered plurality of network addresses in association with said particular domain name in a cache local to said resolver, wherein responsive to a next request for said particular domain name said resolver retrieves from said local cache a particular network address from among said plurality of addresses previously indicated by said router as said shortest path.

2. The system according to claim 1, said resolver for searching said local cache for said particular domain name and only querying said domain name server with said particular domain name responsive to said local cache returning empty of any valid network addresses associated with said particular domain name.

3. The system according to claim 1, further comprising:

an application for sending a request to said resolver for said particular domain name; and

said resolver, responsive to receiving said ordered plurality of network addresses, for returning to said application said particular network addressed indicated by said router as said shortest path.

4. The system according to claim 1, further comprising:

an application for sending a request to said resolver for said particular domain name; and

said resolver for specifying said at least one source address from at least one particular network address accessible to said application at a client system.

5. The system according to claim 1, said router enabled to receive and respond to said shortest path query.

6. The system according to claim 1, said router for detecting each said separate length for each path through at least one router protocol also implemented by said router for detecting a network topology and determining packet routing.

7. The system according to claim 5, wherein said at least one router protocol is at least one from among Routing Information Protocol, Open Shortest Path First, and Border Gateway Protocol.

8. The system according to claim 1, said resolver for converting said ordered plurality of network addresses from a first ordering protocol used by said router to a second ordering protocol used by said resolver prior to caching said plurality of network addresses ordered according to said second ordering protocol in said local cache.

9. A method for caching, in a cache associated with a resolver executing on at least one computer system, a shortest path from a client system to a multihomed server, comprising:

querying, from said resolver, a domain name server for any network addresses associated with a particular domain name;

responsive to detecting said domain name server return a plurality of network addresses, sending a shortest path query from said resolver to at least one router, wherein said shortest path query specifies at least one source addresses and said plurality of network addresses;

detecting, at said router, a separate length for each path accessible between said at least one source address and each of said plurality of network address;

ordering, at said router, said plurality of network addresses to indicate a shortest path to a longest path and sending said ordered plurality of network addresses to said resolver; and

responsive to said resolver receiving said ordered plurality of network addresses, caching said ordered plurality of network addresses in association with said particular domain name in said cache, wherein responsive to a next request for said particular domain name said resolver retrieves from said cache a particular network address from among said plurality of addresses previously indicated by said router as said shortest path.

10. The method according to claim 9, further comprising:

searching, by said resolver, said cache for said particular domain name; and

only querying said domain name server with said particular domain name responsive to said cache returning empty of any valid network addresses associated with said particular domain name.

11. The method according to claim 9, further comprising:

sending, from an application, a request to said resolver for resolution of said particular domain name; and

responsive to receiving said ordered plurality of network addresses at said resolver, returning from said resolver to said application said particular network addressed indicated by said router as said shortest path.

12. The method according to claim 9, further comprising:

sending, from an application, a request to said resolver for resolution of said particular domain name; and

specifying, by said resolver in said shortest path query, said at least one source address from at least one particular network address accessible to said application at a client system.

13. The method according to claim 9, wherein said router is enabled to receive and respond to said shortest path query.

14. The method according to claim 9, further comprising:

detecting, at said router, each said separate length for each path through at least one router protocol also implemented by said router for detecting a network topology and determining packet routing.

15. The method according to claim 14, wherein said at least one router protocol is at least one from among Routing Information Protocol, Open Shortest Path First, and Border Gateway Protocol.

16. The method according to claim 9, further comprising:

converting, at said resolver, said ordered plurality of network addresses from a first ordering protocol used by said router to a second ordering protocol used by said resolver prior to caching said plurality of network addresses ordered according to said second ordering protocol in said cache.

17. A program for offering an alternative product package offer comprising a computer readable medium including a computer readable program, wherein the computer readable program when executed on a computer causes the computer to:

query a domain name server for any network addresses associated with a particular domain name;

responsive to detecting said domain name server return a plurality of network addresses, send a shortest path query to at least one router, wherein said shortest path query specifies at least one source addresses and said plurality of network addresses, wherein said router is enabled to receive said shortest path query, detect a separate length for each path accessible between said at least one source address and each of said plurality of network addresses and return said plurality of network addressed ordered to indicate a shortest path to a longest path; and

responsive to receiving said ordered plurality of network addresses, cache said ordered plurality of network addresses in association with said particular domain name in a local cache, wherein responsive to a next request for said particular domain name said particular network address from among said plurality of addresses previously indicated by said router as said shortest path is retrieved from said cache.

18. The program according to claim 17, wherein the computer readable program when executed on a computer causes the computer to:

search said cache for said particular domain name; and

only query said domain name server with said particular domain name responsive to said cache returning empty of any valid network addresses associated with said particular domain name.

19. The program according to claim 17, wherein the computer readable program when executed on a computer causes the computer to:

receive a request for resolution of said particular domain name from a particular application; and

responsive to receiving said ordered plurality of network addresses, respond to said application with said particular network addressed indicated by said router as said shortest path.

20. The program according to claim 17, wherein the computer readable program when executed on a computer causes the computer to:

convert said ordered plurality of network addresses from a first ordering protocol used by said router to a second ordering protocol used by said computer readable program prior to caching said plurality of network addresses ordered according to said second ordering protocol in said cache.