Rate-Controlled Optical Burst Switching

• US 20070115956A1
• Filed: 01/23/2007
• Published: 05/24/2007
• Est. Priority Date: 11/13/2001
• Status: Active Grant

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Rockstar Consortium US LP (Rockstar Consortium Inc.)
• Inventors: Jamoussi, Bilel, Beshai, Maged
• Granted Patent: US 8,406,246 B2
• Time in Patent Office: Days
• US Class Current: 370/369
• CPC Class Codes: H04L 45/44 Distributed routing
• CPC Class Codes: H04L 47/28 in relation to timing considerations
• CPC Class Codes: H04L 47/39 Credit based
• CPC Class Codes: H04L 47/527 Quantum based scheduling, e.g. credit or deficit based scheduling or token bank
• CPC Class Codes: H04L 47/628 based on packet size, e.g. shortest packet first
• CPC Class Codes: H04L 47/724 at intermediate nodes, e.g. resource reservation protocol [RSVP]
• CPC Class Codes: H04L 47/781 Centralised allocation of resources
• CPC Class Codes: H04L 47/783 Distributed allocation of resources, e.g. bandwidth brokers
• CPC Class Codes: H04L 49/254 Centralised controller, i.e. arbitration or scheduling
• CPC Class Codes: H04L 49/3072 Packet splitting
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 11/0066 Provisions for optical burst or packet networks
• CPC Class Codes: H04Q 2011/0016 using wavelength multiplexing or demultiplexing
• CPC Class Codes: H04Q 2011/0024 using space switching
• CPC Class Codes: H04Q 2011/0039 Electrical control
• CPC Class Codes: H04Q 2011/0064 Arbitration, scheduling or medium access control aspects
• CPC Class Codes: H04Q 2011/0083 Testing; Monitoring
• CPC Class Codes: H04Q 2011/0088 Signalling aspects
• CPC Class Codes: H04W 28/0252 per individual bearer or channel dynamic wireless traffic scheduling H04W72/12
• CPC Class Codes: H04W 28/0257 the individual bearer or channel having a maximum bit rate or a bit rate guarantee
• CPC Class Codes: H04W 28/16 : Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 28/18 : Negotiating wireless communication parameters
• CPC Class Codes: H04W 28/20 : Negotiating bandwidth
• CPC Class Codes: H04W 28/22 : Negotiating communication rate
• CPC Class Codes: H04W 72/12 : Wireless traffic scheduling
• CPC Class Codes: H04W 72/1263 : Mapping of traffic onto schedule, e.g. scheduled allocation or multiplexing of flows
• CPC Class Codes: H04W 72/1268 : of uplink data flows
• CPC Class Codes: H04W 72/1273 : of downlink data flows
• CPC Class Codes: H04W 72/20 : Control channels or signalling for resource management
• CPC Class Codes: H04W 72/21 : in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 : in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/535 : based on resource usage policies
• CPC Class Codes: H04W 74/002 : Transmission of channel access control information
• CPC Class Codes: H04W 74/004 : in the uplink, i.e. towards network
• CPC Class Codes: H04W 74/006 : in the downlink, i.e. towards the terminal

Abstract

A method and apparatus are provided for low latency loss-free burst switching. Burst schedules are initiated by controllers of bufferless core nodes and distributed to respective edge nodes. In a composite-star network, the burst schedules are initiated by any of a plurality of bufferless core nodes and distributed to respective edge nodes. Burst formation takes place at source nodes and a burst size is determined according to an allocated bitrate of a burst stream to which the burst belongs. An allocated bitrate of a burst stream may be modified according to observed usage of scheduled bursts of a burst stream. A method of control-burst exchange between each of a plurality of edge nodes and each of a plurality of bufferless core nodes enables burst scheduling, time coordination, and loss-free burst switching. Both the payload bursts and control bursts are carried by optical channels connecting the edge nodes and the core nodes. A method and a circuit are provided for generating burst descriptors wherein each burst is associated with a burst stream and each burst stream is allocated a service bitrate. The generated burst descriptors are used in each master controller in each core node to create the burst schedules. In a conventional burst-scheduling process, the burst queues at a master controller of an optical switch receives burst descriptors from the source nodes and schedules the burst switching times. In a distinct departure, according to the present invention the burst descriptors are generated by a master controller of an optical switch in a core node, the switching times of the corresponding bursts are scheduled, and the schedules are distributed to the respective edge nodes. The burst-descriptor generation is based on burst-stream bitrate-allocation defined by the source nodes.

Claims

1. A method of burst switching in a network that includes at least one core node and a plurality of edge nodes, comprising the steps of:

generating, by a core node from among said at least one core node, at least one edge-node-specific burst transfer permit;

distributing, by said core node, said at least one edge-node-specific permit to at least one of said plurality of edge nodes; and

sending, by at least one of said plurality of edge nodes, data bursts to said core node, the data bursts being assembled responsive to information in said burst-transfer permit.

2. The method of claim 1 wherein said core node and edge nodes are arranged on a composite-star configuration with a second core node, and including the further step of sending, with each core node, burst-transfer permits to said plurality of edge nodes.

3. The method of claim 2 including the further step of specifying, with each of said edge-node-specific burst transfer permits, burst size and destination.

4. The method of claim 3 including the further step of specifying, with said edge-node-specific burst transfer permits, arrival time at said core node.

5. The method of claim 4 including the further step of receiving, with each edge node, permits from each core node.

6. The method of claim 5 including the further step of each edge node sending data bursts to each core node according to a burst size specified by a respective permit.

7. The method of claim 6 including the further step of each of said edge nodes determining the timing of transmitting data bursts to each core node so that each of said data bursts arrives at a corresponding core node at said required arrival time.

8. The method of claim 7 including the further step of an edge node simultaneously transferring data bursts to a plurality of core nodes.

9. The method of claim 8 wherein said network has collocated edge nodes and core nodes, and including the further step of facilitating said timing by substantially equalizing propagation-delays from the edge nodes to the core nodes.

10. The method of claim 8 including the further step of facilitating said timing by time locking each edge node to each core node.

11. The method of claim 1 including the further step of causing said edge-node-specific burst-transfer permits to be conflict-free.

12. Network communication equipment that facilitates burst switching, comprising:

a plurality of edge nodes;

a core node having a plurality of optical switches, each of said optical switches including;

a burst scheduler operative to generate at least one edge-node-specific burst transfer permit;

a transmitter operative to distribute said at least one edge-node-specific permit to a plurality of edge nodes; and

a receiver operative to receive data bursts sent from said edge nodes to said core node, wherein said data bursts are assembled responsive to information in said burst-transfer permit.

13. The equipment of claim 12 including a second core node arranged with said first core node and said edge nodes in a composite-star configuration, and wherein said second core node also includes a burst scheduler such that each of said core nodes is operative to send burst-transfer permits to said plurality of edge nodes.

14. The equipment of claim 13 wherein said edge-node-specific burst transfer permit indicates burst size and destination.

15. The equipment of claim 14 wherein said edge-node-specific burst transfer permit specifies arrival time at said core node.

16. The equipment of claim 15 further including a receiver in each edge node operative to i receive permits from a plurality of core nodes.

17. The equipment of claim 16 farther including a transmitter in each edge node operative to send data bursts to each of said plurality of core nodes according to burst size specified by a respective permit.

18. The equipment of claim 17 further including a timing controller in at least one output port of each said edge node operative to determine the timing of transmitting data bursts to a A plurality of core nodes so that each of said data bursts arrives at a corresponding core node at said specified arrival time.

19. The equipment of claim 18 further including a plurality of transmitters in each edge node operative to simultaneously transfer data bursts to a plurality of core nodes.

20. The equipment of claim 18 wherein said edge nodes and core nodes are collocated, and wherein propagation-delays from the edge nodes to the core nodes are substantially equalized.

21. The equipment of claim 18 wherein each edge node is time locked to at least one optical switch in a core node.

22. The equipment of claim 12 further including a scheduler operative to cause said edge-node-specific burst-transfer permits to be conflict-free.

23. A method of burst switching in a communication network having at least one core node and a plurality of edge nodes, comprising the steps of:

sending, by at least one of the edge nodes, a bitrate allocation request for a node pair, said request being sent to a controller of a core node from among said at least one core node;

generating, by said controller of the core node, at least one edge-node-specific burst transfer permit corresponding to the bitrate allocation request, including updating the bitrate allocation request for the node pair and including an updated bitrate allocation on the burst transfer permit;

distributing said at least one edge-node-specific burst transfer permit by said controller to at least one of the plurality of edge nodes; and

sending data bursts from at least one of the plurality of edge nodes to said core node based at least in part upon said burst-transfer permit.

24. The method of claim 23 including the further step of specifying, with each said edge-node-specific burst transfer permit, burst size and destination.

25. The method of claim 24 including the further step of specifying, with each said edge-node-specific burst transfer permit, arrival time at said core node.

26. The method of claim 23 wherein said data burst is associated with a burst stream and including the further step of sizing the data burst based at least in part on at least one attribute of the burst stream to which said burst belongs.

27. The method of claim 26 wherein said attribute is a bitrate allocation.

28. The method of claim 27 wherein said attribute is a service class.

29. The method of claim 23 wherein bitrate-allocation requests are associated with a burst stream and including the further step of switching all bursts of a burst stream in the same core node.

30. The method of claim 23 including the further step of time locking each of said plurality of source nodes to said core node.

31. The method of claim 23 including the further step of said core node generating said burst-transfer schedules periodically.

32. The method of claim 24 including the further step of setting a lower bound for said burst size based at least in part on guard-time requirement.

33. The method of claim 24 including the further step of setting an upper bound for said burst size based at least in part on delay-jitter requirements.

34. The method of claim 24 wherein said burst size is limited by a burst-formation delay.