Virtual Output Queue Network Switch Packet Scheduling
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Solution Overview
Problem
High-performance computing systems experience network congestion due to multi-destination packets, which are replicated across all or a subset of output ports, leading to bandwidth reduction and performance issues for other packet streams.
Innovation Solution
A system that schedules multi-destination packets for communication through a network switch fabric with a virtual output queue (VOQ) architecture, inserting packets one at a time into separate VOQs associated with multiple output ports, using a port order list to determine the ordering based on bandwidth, congestion, or fullness, ensuring efficient distribution without interfering with unicast packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-destination packets are replicated to all or a subset of output ports, then the multi-destination packet can be delivered to multiple destinations, but the bandwidth available for other packets is greatly reduced
Solution Approach 1:
The patent segments the multi-destination packet into multiple copies, inserting each copy into a separate VOQ corresponding to different output ports. This segmentation allows the packet to be distributed to multiple destinations while managing bandwidth consumption through controlled replication timing and prioritization schemes.
2Adaptability or versatility
If multi-destination packets are sent through the switch fabric, then multiple destinations can receive the packet, but network congestion increases and performance of other packet streams deteriorates
Solution Approach 1:
The patent performs preliminary actions by inserting multi-destination packet copies into VOQs before actual transmission, allowing the switch fabric to pre-configure the distribution path. The port order list is prepared in advance to determine the optimal transmission sequence, reducing congestion during actual packet forwarding.
Solution Approach 2:
The patent implements dynamic scheduling by maintaining a port order list that can be adjusted based on current network conditions, VOQ states, and packet priorities. This dynamic approach allows the system to adapt to changing traffic patterns and minimize congestion impact on overall network productivity.
3Productivity
If multi-destination packets are inserted into multiple VOQs simultaneously, then all output ports can receive the packet efficiently, but the complexity of managing packet insertion increases
Solution Approach 1:
The patent segments the packet insertion process into sequential operations, where copies are inserted into different VOQs one after another according to the port order list. This segmentation simplifies the management complexity by breaking down the simultaneous insertion task into manageable sequential steps while maintaining distribution efficiency.
Data Source
AI summary
A system for communicating a multi-destination packet through a network switch fabric with a plurality of input and output ports is described. This system receives the multi-destination packet at an input port, wherein the multi-destination packet includes a multicast packet or a broadcast packet that is directed to multiple output ports, and wherein the network switch fabric maintains a separate virtual output queue (VOQ) for each output port. Next, the system sends the multi-destination packet from the input port to the multiple output ports by inserting the multi-destination packet into VOQs associated with the multiple output ports. The multi-destination packet is inserted into one VOQ at a time, so that after the multi-destination packet is read out of a VOQ and is sent to a corresponding output port, the multi-destination packet is inserted in another VOQ until the multi-destination packet is sent to all of the multiple output ports.