Apparatus and method for guaranteeing isochronous data flow on a CSMA/CD network
First Claim
1. A method for transmitting isochronous and non-isochronous data in a non-isochronous communication system having a plurality of nodes, comprising:
- providing predetermined time frames in said non-isochronous communication system;
reserving at least a portion of said predetermined time frames for transmission of isochronous data by at least one of said plurality of nodes that requests a time frame reservation;
sending notification to other nodes in said system of said time frame reservation, wherein said other nodes register said time frame reservation when said nodes have time frame reservation registration capability;
transmitting said isochronous data during said reserved portion of said predetermined time frames; and
contending for non-reserved portions of said predetermined time frames for transmission of non-isochronous data.
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Accused Products
Abstract
A contention protocol permitting transmission of isochronous data. A device (104) wishing to transmit isochronous data can reserve periodic time slots for the transmission. Either the device (104) or a network controller (101) transmits the reservation information to other devices (106, 108) on the network. When non-isochronous transmissions are desired, the devices (104, 106, 108) contend for access using the CSMA/CD protocols, but taking into account the already reserved time slots. For example, the reserved period may be added to the randomly chosen backoff window. Alternatively, if a backoff window expires during a reserved period, the backoff window may be restarted upon completion of the reserved period. If not all the devices (104, 106, 108) on the network employ this modified CSMA/CD protocol, a "dummy" frame is provided at the beginning of each isochronous transmission. If another device is contending for access, the dummy frame collides, and the other device backs off. The isochronous transmission then proceeds.
59 Citations
20 Claims
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1. A method for transmitting isochronous and non-isochronous data in a non-isochronous communication system having a plurality of nodes, comprising:
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providing predetermined time frames in said non-isochronous communication system;
reserving at least a portion of said predetermined time frames for transmission of isochronous data by at least one of said plurality of nodes that requests a time frame reservation;sending notification to other nodes in said system of said time frame reservation, wherein said other nodes register said time frame reservation when said nodes have time frame reservation registration capability; transmitting said isochronous data during said reserved portion of said predetermined time frames; and contending for non-reserved portions of said predetermined time frames for transmission of non-isochronous data. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A network system comprising:
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a bus; and a plurality of network devices coupled to said bus, a predetermined number of said plurality of network devices including; an isochronous controller; and a non-isochronous controller; wherein said isochronous controller is configured to reserve at least one time slot for said transmission of isochronous data in response to a request made for reservation of at least one time slot, and wherein said isochronous controller is configured to send notification to other network devices of said reservation when said other network devices have time slot reservation registration capability, and wherein said non-isochronous controller is configured to contend for bus access with others of said plurality of network devices during periods other than said time slots for transmission of non-isochronous data. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A network system for transmitting isochronous and non-isochronous data in a non-isochronous communication system, comprising:
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means for providing predetermined non-isochronous time frames in said non-isochronous communication system;
means for requesting a reservation of predetermined numbers of said non-isochronous time frames;means for sending notification of said reservation to devices in said network system that have reservation registering capability; means for reserving predetermined numbers of said non-isochronous time frames for transmission of isochronous data; and means for contending for non-reserved non-isochronous time frames for transmission of non-isochronous data. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification