Infiniband Switch Shared Output Buffering
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Solution Overview
Problem
Infiniband network switches face challenges in reducing latency and increasing efficiency due to resource contention, which leads to delays in packet transmission, while also requiring cost-effective and compact designs to minimize integrated circuit area usage.
Innovation Solution
The implementation of a switch with a plurality of input/output ports, where each port has associated input and output buffers, allowing for parallel transmission of packets across a switching matrix and shared output buffers, with an output buffer select signal to optimize packet transfer efficiency and reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resource contention within the switch is minimized to reduce delays, then packet transmission efficiency is improved, but device complexity increases due to the need for multiple output buffers per port
Solution Approach 1:
Multiple ports share a common pool of output buffers instead of each port having dedicated buffers. The switching matrix routes packets from input buffers to the shared output buffer pool, and a buffer select signal mechanism assigns packets to specific output buffers, reducing overall device complexity while maintaining transmission efficiency.
Solution Approach 2:
The shared output buffer pool serves multiple ports simultaneously, making the buffer resources universal. Any port can utilize any available output buffer in the shared pool, allowing the same buffer resources to be reused across different ports and time periods, thereby reducing the total number of buffers needed.
2Area of stationary object
If the number of output buffers per port is reduced to minimize integrated circuit area, then device area is decreased, but resource contention increases causing transmission delays
Solution Approach 1:
The patent merges the output buffers of multiple ports into a single shared pool, reducing the total integrated circuit area required. Instead of each port having separate buffers, the shared pool is accessed by multiple ports through the switching matrix and buffer select signal mechanism, minimizing area while avoiding resource contention delays.
Solution Approach 2:
The patent introduces a new dimension of resource sharing by allowing temporal and spatial multiplexing of buffer resources across multiple ports. The buffer select signal mechanism enables dynamic assignment of buffers to different ports at different times, effectively utilizing the same physical buffers for multiple purposes without causing delays.
3Loss of time
If dedicated output buffers are allocated to each port to eliminate resource contention, then packet transmission delay is reduced, but device area and cost increase
Solution Approach 1:
The patent combines the output buffer resources of multiple ports into a shared pool, eliminating the need for dedicated buffers at each port. This merging approach reduces the total integrated circuit area while the buffer select signal mechanism ensures that packets are efficiently routed to available buffers, preventing contention-induced delays.
Solution Approach 2:
The patent introduces dynamic buffer allocation through the buffer select signal mechanism, which dynamically assigns output buffers to packets based on current port needs and buffer availability. This dynamic approach allows the same physical buffers to be flexibly allocated to different ports at different times, achieving low latency without requiring static dedicated buffer allocation.
Data Source
AI summary
An Infiniband device is provided. The device has a plurality of input/output ports. Each port has associated therewith an input buffer for storage of a packet received at that port. Each port also has associated therewith a plurality of output buffers for storage of a packet transmitted from an input buffer via a switching matrix. Each port is arranged to share its associated plurality of output ports with at least one other port. Each input buffer is also associated with a single output buffer of each shared plurality of output buffers. A packet received at an input buffer is transmitted to all associated output buffers via the switching matrix in parallel with an output buffer select signal. The output buffer select signal is sent to less than all of the associated output buffers, any output buffer not receiving the output buffer select signal is configured to discard the packet transmitted from the input buffer.