Method of and system for managing a SONET ring

• US 6,389,015 B1
• Filed: 08/10/1998
• Issued: 05/14/2002
• Est. Priority Date: 08/10/1998
• Status: Expired due to Term

• Current Assignee: Rakuten, Inc. (Rakuten Group, Inc.)
• Original Assignee: MCI Communications Corporation (Verizon Communications Inc.)
• Inventors: Huang, Jennifer, Khalil, Anis, Nathan, Sridhar
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Pham, Brenda H.
• Application Number:
  US09/131,538
• Time in Patent Office: 1,373 Days
• Field of Search: 370/258, 370/280, 370/294, 370/314, 370/375, 370/376, 370/404, 370/235, 370/230, 370/458, 370/459, 370/452
• US Class Current: 370/376
• CPC Class Codes: H04J 2203/0042 Ring
• CPC Class Codes: H04J 2203/0055 Network design, dimensioning, topology or optimisation
• CPC Class Codes: H04J 2203/0098 Traffic aspects, e.g. arbitration, load balancing, smoothing, buffer management
• CPC Class Codes: H04L 12/422 Synchronisation for ring networks Time Division Multiplex ring networks, e.g. SDH/SONET H04J3/085

Abstract

A method of and system for managing a SONET ring computes an optimally balanced demand loading for the SONET ring and generates an updated time slot assignment map for each node of the SONET ring based upon the optimally balanced demand loading. The method causes each node of the SONET ring to switch substantially simultaneously to its updated time slot assignment map, thereby reconfiguring the SONET ring.

Claims

1. A method of managing a SONET ring, which comprises the steps of:

(a) computing an optimally balanced demand loading for said SONET ring, wherein each link of said SONET ring carries substantially the same demand as every other link of said SONET ring;

(b) generating an updated time slot assignment map for each node of said SONET ring based upon said optimally balanced demand loading; and

,

(c) causing each node of said SONET ring to switch substantially simultaneously to said updated time slot assignment map generated for said each node.

2. The method as claimed in claim 1, including the step of:

freezing provisioning activity on said SONET ring during the performance of steps (a)-(c).

3. The method as claimed in claim 1, including the step of performing steps (a)-(c) periodically.

4. The method as claimed in claim 3, including the step of performing steps (a)-(c) quarterly.

5. The method as claimed in claim 1, wherein said step of causing each node of said SONET ring to switch substantially simultaneously to said updated time slot assignment map generated for said each node includes the step of:

downloading to each node of said SONET ring the updated time slot assignment map generated for said each node.

6. The method as claimed in claim 5, wherein said step of causing each node of said SONET ring to switch substantially simultaneously to said updated time slot assignment map generated for said each node includes the step of:

sending to said each node a time to switch to said downloaded updated time slot assignment map.

8. The method as claimed in claim 1, wherein said step of computing an optimally balanced demand loading for said SONET ring includes the steps of:

(d) defining for each pair of links of said SONET ring a two-edge cut, each two-edge cut dividing said ring into a first set of nodes on one side of said two-edge cut and a second set of nodes on the other side of said two-edge cut;

(e) calculating, for each two-edge cut, the sum of demands between the nodes of said first set and the nodes of said second set;

(f) calculating, for each two-edge cut, the sum of the capacities of the links of said each two-edge cut;

(g) calculating, for each two-edge cut, a cut difference equal to the difference between the sum of the capacities of the links of said each two-edge cut and the sum of demands between the nodes of said first set and the nodes of said second set;

(h) if any two-edge cut has a cut difference equal to or less than one and a demand greater than zero between nodes of said first set or a demand greater than zero between nodes of said second set, routing the demands between nodes of said first set on a line formed by the nodes of said first set and routing the demands between nodes of a second set on a line formed by the nodes of said second set;

(i) if any two-edge cut has a cut difference equal to or less than one and no demand greater than zero between nodes of said first set and no demand greater than zero between nodes of said second set, routing a portion of the demand between a selected node of said first set and a selected node of said second set on a line formed by the selected node of said first set and the selected node of said second set; and

repeating steps (e) through (i) until a terminating condition occurs.

9. The method as claimed in claim 8, wherein said demand portion of the demand between a selected node of said first set and a selected node of said second set is equal to the minimum of:

(i) the demand between said selected node of said first set and said selected node of said second set;

(ii) the minimum capacity of a link on said line formed by the selected node of said first set and the selected node of said second set; and

,

(iii) one-half the capacity of any adjacent two-edge cut on said line formed by the selected node of said first set and the selected node of said second set.

10. The method as claimed in claim 8, wherein a terminating condition occurs whenever the demand between each pair of nodes of said rings is equal to zero.

11. The method as claimed in claim 8, wherein a terminating condition occurs whenever the capacity of any link of said ring is less than one.

12. The method as claimed in claim 8, wherein any adjacent two-edge cut has a cut difference equal to or less than one.

13. The method as claimed in claim 8, wherein the line formed by the selected node of said first set and the selected node of said second set is the line between the selected node of said first set and the selected node of said second set with the fewest number of nodes.

7. The method as claimed in 1, including the step of determining if any element of said SONET ring is in protection mode prior to performing step (c).

14. A system for managing a SONET ring, which comprises:

means for computing an optimally balanced demand loading for said SONET ring wherein each link of said SONET ring carries substantially the same demand as every other link of said SONET ring;

means for generating an updated time slot assignment map for each node of said SONET ring based upon said optimally balanced demand loading; and

,

means for causing each node of said SONET ring to switch substantially simultaneously to said updated time slot assignment map generated for said each node.

15. The system as claimed in claim 14, including:

means for freezing provisioning activity on said SONET ring.

16. The system as claimed in claim 14, wherein means for causing each node of said SONET ring to switch substantially simultaneously to said updated time slot assignment map generated for said each node includes:

means for downloading to each node of said SONET ring the updated time slot assignment map generated for said each node.

17. The system as claimed in claim 16, wherein means for causing each node of said SONET ring to switch substantially simultaneously to said updated time slot assignment map generated for said each node includes:

means for sending to said each node a time to switch to said downloaded updated time slot assignment map.

18. A SONET ring system, which comprises:

a plurality of nodes interconnected by links in a ring topology, each of said nodes including means for storing an active time slot assignment map and a secondary time slot assignment map, and each of said nodes including means for substituting a secondary time slot assignment map for an active time slot allocation map at a designated time; and

,

a ring management system in communication with each node of said SONET ring, said ring management system including;

means for computing an optimally balanced demand loading for said SONET ring;

means for generating a secondary time slot assignment map for each node of said SONET ring based upon said optimally balanced demand loading; and

,

means for downloading to each node of said SONET ring a secondary time slot assignment map generated for said each node and a designated time for said each node to swap substitute said downloaded secondary time slot assignment map.

19. The system as claimed in claim 18, wherein said ring management system includes:

means for freezing provisioning activity on said SONET ring.

20. The system as claimed in claim 18, wherein said means for computing an optimally balanced demand loading for said SONET ring includes means for computing a demand loading for said SONET ring wherein each link of said SONET ring carries substantially the same demand as every other link of said SONET ring.