Multicast Packet Reliability in Multi-Node Graphics Systems
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Solution Overview
Problem
Multicast transmissions in IP networks are unreliable, leading to missed or distorted data packets, which is problematic for applications requiring real-time and continuous data delivery, such as high-end computer graphics systems where packet loss results in incomplete or delayed graphics displays.
Innovation Solution
Implementing logic at the master node to pace multicast transmissions and ensure reliable delivery by using a retransmission mechanism where unacknowledged packets are resent via multicast protocol to all nodes, with optional delays and acknowledgments from a predetermined number of render nodes to maintain system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multicast transmissions are used for real-time graphics data delivery, then system throughput and efficiency are improved, but data reliability deteriorates due to packet loss and distortion
Solution Approach 1:
The patent implements an acknowledgment mechanism where receiving nodes send feedback packets to the transmitting node to confirm receipt of graphics data packets. The transmitting node monitors these acknowledgments and retransmits unacknowledged packets, ensuring reliable delivery while maintaining multicast efficiency for real-time graphics rendering.
Solution Approach 2:
The patent establishes a predetermined acknowledgment timeout period before triggering retransmission. This preliminary timing mechanism allows the system to efficiently determine whether retransmission is necessary without unnecessarily delaying real-time graphics data delivery, balancing reliability with throughput.
2Reliability
If individual retransmission is implemented for lost packets, then data integrity is improved, but system delay increases
Solution Approach 1:
The patent combines multiple retransmission requests into a single multicast retransmission packet. When the transmitting node receives acknowledgments from some nodes but not others, it retransmits the missing packet to all nodes simultaneously via multicast, rather than individually addressing each node. This merging approach maintains data integrity while minimizing delay by efficiently utilizing the multicast channel.
3Reliability
If acknowledgment packets are sent from all receiving nodes, then packet delivery confirmation is improved, but network traffic increases
Solution Approach 1:
The patent designs the acknowledgment packets to serve multiple functions: they confirm receipt of graphics data packets, trigger retransmission when needed, and enable the transmitting node to track delivery status. This multi-functionality reduces the need for separate control messages, optimizing network traffic while maintaining reliable delivery confirmation.
Data Source
AI summary
Embodiments of the present invention are broadly directed to novel systems and methods for providing reliable multicast of data in a multi-node graphics system. In accordance with one embodiment of the invention, a multi-node computer graphics system is provided comprising a master node capable of executing a graphics application and a plurality of render nodes configured to collectively render a graphic image, in response to graphics data communicated from the master node. The embodiment further comprises logic associated with the master node for communicating graphics data to the plurality of render nodes in a multicast packet. Additional logic, associated with the master node, is provided for determining whether a predetermined number of render nodes have acknowledged receipt of the multicast packet. The embodiment further comprises logic associated with the master node for re-transmitting the multicast packet to the plurality of render nodes, if the predetermined number of render nodes have not acknowledged receipt of the multicast packet within a given time.