Automatic link establishment between distributed servers through an NBMA network

• US 6,327,252 B1
• Filed: 10/05/1998
• Issued: 12/04/2001
• Est. Priority Date: 10/03/1997
• Status: Expired due to Term

• Current Assignee: Alcatel Canada Inc. (Nokia Corporation)
• Original Assignee: Alcatel Canada Inc. (Nokia Corporation)
• Inventors: Bajpai, Sirish, Silton, Roderick P.
• Primary Examiner(s): Olms, Douglas
• Assistant Examiner(s): PIZARRO, RICARDO M
• Application Number:
  US09/166,550
• Time in Patent Office: 1,156 Days
• Field of Search: 370/395, 370/396, 370/397, 370/469, 370/399, 370/466, 370/400, 370/254, 370/255, 370/256, 370/465, 370/401, 370/410, 370/474, 370/475, 709/222, 709/225, 709/249, 709/245, 709/220
• US Class Current: 370/256
• CPC Class Codes: H04L 2012/5627 Fault tolerance and recovery
• CPC Class Codes: H04L 43/0811 by checking connectivity
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/18 Loop-free operations
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/48 Routing tree calculation

Abstract

The invention relates to distributed computer or server networks and to methods of automatically establishing communication links between individual servers in the network. By taking advantage of the properties of group addresses (anycast addresses) inherent in certain networking technologies, coupled with innovative discovery and hunt protocols the servers in the network all become members of an overlay spanning tree where the tree is comprised of servers as nodes and communication links as edges. Discovery and hunt protocols are implemented to locate peer servers in the network and communication links are set up as required.

Claims

1. A method of joining a new server to a group of zero or more servers connected via a non-broadcast multi-access (NBMA) communications network comprising the steps of:

in a first mode, attempting to establish a connection between the new server and an anycast address associated with the group of servers that the new server desires to join; and

if the new server successfully establishes the connection to the anycast address, it registers the anyeast address with the communications network whereby registration informs the network that the new server is joined to the group of servers having the anycast address, and the new server maintains information respecting another server in the group to which it is connected including a natural address of the another server.

2. The method as defined in claim 1 wherein, if the connection is not successfully established on a first attempt, the new server retries to establish the connection.

3. The method as defined in claim 2 wherein the new server makes up to three retries at one second intervals to establish a connection to the anycast address.

4. The method as defined in claim 1 wherein if the new server fails to establish a connection to the anycast address it declares itself to be a root node and enters into a second mode.

5. The method as defined in claim 4 wherein said anycast address comprises a discovery address.

6. The method as defined in claim 4 wherein said second mode comprises a hunt mode.

7. A method of joining a new server to a group of interconnectable zero or more servers via a non-broadcast multi-access (NBMA) communications network comprising the steps of:

attempting to establish a connection between the new server and a discovery anycast address associated with the group of servers that the new server desires to join;

if the new server successfully establishes the connection to the discovery anycast address the new server registers its discovery anycast address with the communications network whereby registration informs the network that the new server is joined to the group associated with the anycast address and the new server maintains information respecting another server in the group to which it is connected including a natural address of the another server, and if the new server does not successfully establish a connection to the discovery anycast address, the new server declares itself to be a root node and flags this status internally to reflect that it is a root server.

8. The method according to claim 7 wherein if the new server is unable to successfully establish a connection to the discovery anycast address after a preset number of attempts, it enters a hunting mode in which the new server attempts to establish a connection on a hunt anycast address.

9. The method of claim 8 wherein the new server also enters the hunting mode upon detection that a connection between said new server and a group of servers has been lost.

10. A method of joining a new server to a group of servers via a non-broadcast multi-access (NBMA) communications network comprising the steps of:

successively registering the new server to an anycast address followed by a period of de-registering and attempting to establish a connection on the anycast address and continuing the registering and de-registering steps until a successful joining of the new server to the group of servers is established and, if no such successful joining is established, attempting to join the new server to the group of servers using a hunt anycast address.

11. The method of claim 10 wherein the anycast address to which the new server is successively registered is a hunt anycast address.

12. The method of claim 10 wherein the new server attempts to join the group of servers after a loss in a connection between the new server and the group of servers has been detected.

13. The method of claim 11 wherein the new server attempts to join the group of servers using the hunt address if the new server is unable to establish a connection utilizing a discovery anycast address.

14. The method of claim 13 wherein, if the new server successfully establishes the connection to the anycast address, it registers the anycast address with the communications network whereby registration informs the network that the new server is joined to the group associated with the anycast address.

15. The method of claim 10 wherein the registering and de-registering steps occur in a semi-random fashion.

16. The method of claim 15 wherein different time intervals are used for registering and de-registering.