Bandwidth defragmentation systems and methods in optical networks

• US 8,666,247 B2
• Filed: 11/15/2010
• Issued: 03/04/2014
• Est. Priority Date: 08/25/2010
• Status: Active Grant

• Current Assignee: Ciena Corporation
• Original Assignee: Ciena Corporation
• Inventors: Khan, Waseem Reyaz, Prakash, Anurag, Srinivasan, Hari, Pandey, Saurabh
• Primary Examiner(s): Vanderpuye, Ken
• Assistant Examiner(s): SANDHU, AMRITBIR K
• Application Number:
  US12/945,956
• Publication Number:
  US 20120051745A1
• Time in Patent Office: 1,205 Days
• Field of Search: 398/57
• US Class Current: 398/57
• CPC Class Codes: H04J 2203/0058 Network management, e.g. Intelligent nets
• CPC Class Codes: H04J 3/1611 Synchronous digital hierarchy [SDH] or SONET H04J3/1664 takes precedence for interactions with OTN
• CPC Class Codes: H04J 3/1652 Optical Transport Network [OTN]
• CPC Class Codes: H04L 45/123 Evaluation of link metrics techniques for monitoring network metrics H04L43/08
• CPC Class Codes: H04L 45/125 based on throughput or bandwidth
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 45/62 Wavelength based optical switching H04Q11/0062

Abstract

The present disclosure provides bandwidth defragmentation systems and methods in optical networks such as Optical Transport Network (OTN), Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH), Ethernet, and the like. In particular, the present invention includes bandwidth defragmentation algorithms that may be used within the context of a signaling and routing protocol to avoid bandwidth defragmentation. As such, the present invention defines a mechanism for computing an end to end path for a connection in a manner that avoids bandwidth fragmentation and provides for better network utilization. For example, the present invention may include a path computation based upon administrative weight and upon fragmentation costs. This may be implemented in existing signaling and routing protocols without changes to existing protocol messages used in topology discovery. Further, the present invention optimizes available bandwidth allowing a higher probability of higher bandwidth request being admitted.

Claims

1. A network, comprising:

a plurality of nodes;

a plurality of links interconnecting the plurality of nodes, wherein the plurality of links comprise a bandwidth hierarchy;

a signaling and routing protocol operated between the plurality of nodes and configured to establish bandwidth connections over the plurality of links between the plurality of nodes; and

a bandwidth defragmentation algorithm utilized within the signaling and routing protocol to optimize the bandwidth hierarchy on the plurality of links;

wherein the bandwidth defragmentation algorithm utilizes and compares a relative fragmentation cost metric for each of the plurality of links after an administrative weight for each of the plurality of links has been utilized and compared by a path selection algorithm; and

wherein the relative fragmentation cost metric quantifies bandwidth fragmentation for each of the plurality of links on a weighted per link basis.

2. The network of claim 1, wherein the bandwidth defragmentation algorithm comprises assigning the relative fragmentation cost metric to each of the plurality of links based upon provisioned bandwidth in the bandwidth hierarchy.

3. The network of claim 2, wherein the relative fragmentation cost metric for each of the plurality of links is calculated and stored locally at each of the plurality of nodes based upon advertisements from the signaling and routing protocol.

4. The network of claim 2, wherein the bandwidth defragmentation algorithm comprises selecting a path through the plurality of links and the plurality of nodes based upon the relative fragmentation cost metric for each of the plurality of links.

5. The network of claim 4, wherein the bandwidth defragmentation algorithm is utilized only if there is a tie in the path selection algorithm based upon the administrative weights of the plurality of links.

6. The network of claim 2, wherein the plurality of nodes and the plurality of links utilize Optical Transport Network and the bandwidth hierarchy comprises any of Optical Channel Data Unit-n (n=0, 1, 2, 3, . . . ) and Optical channel Payload Virtual Containers, and wherein the relative fragmentation cost metric is a different value for each of the bandwidth hierarchy.

7. The network of claim 2, wherein the plurality of nodes and the plurality of links utilize Synchronous Optical Network and the bandwidth hierarchy comprises any of Synchronous Transport Signal—

k (k=1, 3, 12, 24, 48, 192, . . . ), and wherein the relative fragmentation cost metric is a different value for each of the bandwidth hierarchy.

8. The network of claim 2, wherein the plurality of nodes and the plurality of links utilize Synchronous Digital Hierarchy and the bandwidth hierarchy comprises any of Synchronous Transport Module level n (n=1, 4, 16, 64, 256, . . . ), and wherein the relative fragmentation cost metric is a different value for each of the bandwidth hierarchy.

9. The network of claim 2, wherein the signaling and routing protocol comprises any of Optical Signaling and Routing Protocol (OSRP), Automatically Switched Optical Networks—

ITU-T Recommendation G.8080;

Architecture for the Automatically Switched Optical Network (ASON) 2001, Generalized Multi-Protocol Label Switching Architecture (G-MPLS) IETF RFC 3945, 2004, and Private Network-Network Interface (PNNI).

10. The network of claim 2, wherein each of the plurality of nodes comprises a control module communicatively coupled to corresponding control modules of other of the plurality of nodes via an in-band or an out-of-band communication mechanism, and wherein the control module is configured to implement the signaling and routing protocol and the bandwidth defragmentation algorithm.

11. The network of claim 3, wherein the relative fragmentation cost metric for each of the plurality of links is dynamically calculated and stored locally at each of the plurality of nodes based upon advertisements from the signaling and routing protocol and based upon updates received via the advertisements.

12. The network of claim 3, wherein the relative fragmentation cost metric is based upon a predefined matrix for the bandwidth hierarchy, and the predefined matrix is established for Optical Transport Network, Synchronous Optical Network, and Synchronous Digital Hierarchy.

13. A network element, comprising:

one or more line modules comprising ingress and egress to a plurality of links in a network;

a control module communicatively coupled to the one or more line modules, wherein the control module is configured to operate a signaling and routing protocol to establish bandwidth connections via the one or more line modules over the plurality of links, and wherein the control module is configured to;

maintain a fragmentation cost of all links in the network;

responsive to a bandwidth request, determine a path through the network for the bandwidth request based upon a path selection algorithm; and

utilize the fragmentation cost subsequent to the path selection algorithm based upon a bandwidth defragmentation algorithm;

wherein the fragmentation cost quantifies bandwidth fragmentation for the plurality of links on a weighted per link basis.

14. The network element of claim 13, wherein to maintain the fragmentation cost comprises assigning a relative fragmentation cost metric to each of the links in the network based upon provisioned bandwidth in a bandwidth hierarchy, and wherein to maintain the fragmentation cost comprises dynamically maintaining the relative metric based upon advertisements from the signaling and routing protocol.

15. The network element of claim 14, wherein the path selection algorithm comprises selecting a path through the links in the network based upon administrative weight and the bandwidth defragmentation algorithm comprises selecting a path through the links in the network based upon the relative fragmentation cost metric, and wherein the relative fragmentation cost metric is utilized only if there is a tie in the path selection algorithm based upon the administrative weight of the links.

16. The network element of claim 13, wherein the relative fragmentation cost metric is based upon a predefined matrix for the bandwidth hierarchy, and the predefined matrix is established for Optical Transport Network, Synchronous Optical Network, and Synchronous Digital Hierarchy.

17. A network operating method with bandwidth defragmentation, comprising:

operating a plurality of nodes interconnected by a plurality of links with a signaling and routing protocol;

maintaining a relative fragmentation cost metric for each of the plurality of links, wherein the relative metric defines fragmentation on each of the plurality of links based upon a bandwidth hierarchy;

selecting a path for a bandwidth connection based upon parameters associated with the plurality of links including the relative fragmentation cost metric; and

updating the relative fragmentation cost metric for each of the plurality of links based upon the selected path for the bandwidth connection;

wherein the relative fragmentation cost metric for each of the plurality of links is utilized and compared after an administrative weight for each of the plurality of links has been utilized and compared; and

wherein the relative fragmentation cost metric quantifies bandwidth fragmentation for each of the plurality of links on a weighted per link basis.

18. The network operating method of claim 17, further comprising:

during path selection, having two or more paths with equal administrative weights and selecting one of the two or more paths based upon the relative fragmentation cost metric defining fragmentation.

19. The network operating method of claim 17, further comprising:

providing advertisements through the signaling and routing protocol; and

locally updating at each of the plurality of nodes the relative fragmentation cost metric for each of the plurality of links based upon the advertisements.

20. The network operating method of claim 17, further comprising:

defining the relative fragmentation cost metric based upon a bandwidth hierarchy for each of Optical Transport Network, Synchronous Digital Hierarchy, and Synchronous Optical Network.