Rate-controlled optical burst switching

• US 7,187,654 B1
• Filed: 11/13/2001
• Issued: 03/06/2007
• Est. Priority Date: 11/13/2001
• Status: Expired due to Fees

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Jamoussi, Bilel N., Beshai, Maged E.
• Primary Examiner(s): To, Doris H.
• Assistant Examiner(s): BLOUNT, STEVEN
• Application Number:
  US10/054,512
• Time in Patent Office: 1,939 Days
• Field of Search: 370/230, 370/231, 370/232, 370/236, 370/235, 370/240, 370/229, 370/251
• US Class Current: 370/251
• 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. In an edge node having ingress ports, output ports, a switching fabric, a controller, and a time counter at each of said output ports, a method of data burst formulation comprising steps of:

receiving burst-transfer permits at said controller, each of the burst transfer permits specifying a burst size;

sorting said burst-transfer permits according to destination;

distributing said burst-transfer permits to respective output ports;

receiving data packets of variable sizes at said ingress ports;

segmenting each of said data packets into segments of a predefined size to produce a segmented packet, wherein a last segment that is smaller than said predefined size is null padded;

switching each of said segments to a corresponding output port;

concatenating, at said corresponding output port, segments of a common destination to form data bursts according to respective burst-transfer permits;

modulating an optical carrier by said data bursts to produce a modulated optical carrier; and

transmitting said modulated optical carrier to a core node.

2. The method of claim 1 wherein said concatenating step includes the further step of removing any null-padding from each segmented packet.

3. The method of claim 2 including the further step of extending the size of a data burst by null-padding to be an integer multiple of a prescribed data-size.

4. The method of claim 3 including the further step of transmitting said data burst at a time based at least in part on a reading of said time counter.