Connectionless communication network

• US 6,574,227 B1
• Filed: 01/12/2000
• Issued: 06/03/2003
• Est. Priority Date: 04/18/1997
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: McCaughan, Daniel Vincent, Rosenberg, Catherine, Mauger, Roy Harold
• Primary Examiner(s): VANDERPUYE, KENNETH N
• Application Number:
  US09/403,175
• Time in Patent Office: 1,238 Days
• Field of Search: 370/321,395.1,395.43,395.21,254,255,439,316,476,474 455/428,422,427,431
• US Class Current: 370/395.65
• CPC Class Codes: H04B 7/18578 Satellite systems for providing broadband data service to individual earth stations for selecting H04W; provisions for broadband connection, H04Q11/0478
• CPC Class Codes: H04B 7/18584 Arrangements for data networking, i.e. for data packet routing, for congestion control data switching networks H04L12/00
• CPC Class Codes: H04B 7/18589 Arrangements for controlling an end to end session, i.e. for initialising, synchronising or terminating an end to end link
• CPC Class Codes: H04L 2012/5608 Satellite
• CPC Class Codes: H04L 2012/5619 Network Node Interface, e.g. tandem connections, transit switching
• CPC Class Codes: H04L 2012/5623 Network design, dimensioning, topology or optimisation
• CPC Class Codes: H04L 2012/563 Signalling, e.g. protocols, reference model
• CPC Class Codes: H04L 2012/5632 Bandwidth allocation
• CPC Class Codes: H04L 2012/5634 In-call negotiation
• CPC Class Codes: H04L 2012/5638 Services, e.g. multimedia, GOS, QOS
• CPC Class Codes: H04L 2012/5645 Connectionless
• CPC Class Codes: H04L 2012/5651 Priority, marking, classes
• CPC Class Codes: H04L 2012/5656 using the AAL2
• CPC Class Codes: H04L 2012/5672 Multiplexing, e.g. coding, scrambling
• CPC Class Codes: H04L 2012/5675 Timeslot assignment, e.g. TDMA
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A connectionless communications network includes a number of low earth orbit (LEO) satellite nodes. Motion of the satellites constantly changes the topology of the network. A virtual model of the network having fixed virtual nodes, is maintained in a connection control system. This virtual model is used to control the route that traffic will take through the real network. As topology changes happen in the network then the virtual nodes of the model become embodied by different real nodes and communicate their virtual identity to connected nodes. Routing of the traffic is performed with reference to the virtual network so that routing follows the current embodiment of the virtual network.

Claims

1. A method of determining routing of traffic in a connectionless network incorporating a plurality of nodes and having a changing topology, the method comprising providing a virtual model of the network, said model consisting of fixed virtual nodes, determining within the model routing for the traffic in the real network, reflecting said topology changes in the network by temporarily associating the virtual nodes of the model with corresponding real nodes so as to provide each said real node with a respective virtual node identity, communicating the virtual identity of each said real node to its neighbouring nodes, and performing traffic routing in the real network with reference to the current embodiment of the virtual network.

2. A method as claimed in claim 1, wherein the network has an available bandwidth which is maintained substantially constant.

3. A method as claimed in claim 1, wherein user traffic is allocated to time slots.

4. A method as claimed in claim 3, wherein, prior to transmission of a message between first and second users, a path request is sent to a connection control centre, and wherein said connection control centre verifies that a said virtual node for said first user and the virtual nodes adjacent that virtual node all have sufficient available time slot capacity.

5. A method as claimed in claim 4, wherein said traffic comprises connectionless packets.

13. A method according to claim 1 wherein the nodes are a plurality of non-geo-stationary satellites.

6. A connectionless communications network incorporating a plurality of nodes and having a changing topology, the network including a virtual model consisting of fixed virtual nodes, there being means for determining within the virtual model routing for traffic in the real network, means for reflecting said topology changes in the network by temporarily associating the virtual nodes of the model with corresponding real nodes so as to provide each said real node with a respective virtual node identity, and means for communicating the virtual identity of each said real node to its neighbouring nodes so as to perform traffic routing in the real network.

7. An arrangement as claimed in claim 6, and having means for maintaining available bandwidth substantially constant as the network topology changes.

8. An arrangement as claimed in claim 6, wherein user traffic is allocated to time slots.

9. An arrangement as claimed in claim 8, wherein, prior to transmission of a message between first and second users, a path request is sent to a connection control centre, and wherein said connection control centre verifies that a said virtual node for said first user and the virtual nodes adjacent that virtual node all have sufficient available time slot capacity.

10. An arrangement as claimed in claim 6 and incorporating topology groups of virtual nodes, the virtual nodes within a said group being fully interconnected.

11. An arrangement as claimed in claim 6 and including a synchronous or plesiochronous digital hierarchy user network interface.

12. An arrangement as claimed in claim 6, and including an synchronous transfer mode (ATM) user network interface.

14. A communications network according to claim 6 wherein the nodes are a plurality of non-geo-stationary satellites.