Method and apparatus for inserting packets into a data stream
AssigneeNortel Networks Limited
InventorsDavid G. Steer, Paul M. Row
Life of this patent
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Abstract
This invention provides a communication network with a method and apparatus for interrupting the transmission of an existing stream of data to insert interrupting packets which may have a higher priority than the existing data stream. The interrupting packets are inserted in the data stream by making use of unused pointer values in common transmission schemes known as the Data Over Cable Service Interchange Specification (DOCSIS) or the Asynchronous Transfer Mode (ATM) adaptation layer 2 (AAL2) format of the International Telecommunications Union (ITU) recommendation I363.2. Advantageously, the scheduling of packets is significantly simplified and the packet jitter is better controlled which results in a significant improvement in transmission performance.
Claims42
A method to interrupt an existing packet in transmission for transmitting an interrupting packet in a communication system where packets are each transmitted in the form of physical layer blocks, the physical layer blocks of each packet containing fields for previously defined purposes and being designed to be consecutively transmitted without interruption, the method comprising:
- transmitting one or more physical layer blocks for the existing packet;
- before completing the transmission of the existing packet, transmitting at least one physical layer block for the interrupting packet;
- denoting the presence of the interrupting packet in the physical layer block for the interrupting packet by using a value or combination of values in one or more existing fields located therein in a manner such that these fields are not used for the defined purposes;
- and
- resuming transmission of the existing packet.
A scheduler for interrupting an existing packet in transmission for transmitting an interrupting packet in a communication system where packets are each transmitted in the form of physical layer blocks, the physical layer blocks of each packet containing fields for previously defined purposes and being designed to be consecutively transmitted without interruption, the scheduler being connected for receiving packets which require transmission and comprising:
- means for transmitting one or more physical layer blocks for the existing packet;
- means for transmitting at least one physical layer block for the interrupting packet before completing the transmission of the existing packet;
- means for denoting the presence of the interrupting packet in the physical layer block for the interrupting packet by using a value or combination of values in one or more existing fields located therein in a manner such that these fields are not used for the defined purposes;
- and
- means for resuming transmission of the existing packet;
- wherein the scheduler is operable to determine for each packet received whether to treat it as an interrupting packet or to wait until completion of an existing packet.
Dependencies are inferred from the claim text.