Sliced NoC Router Architecture for High-Frequency FPGA Data Paths
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Solution Overview
Problem
FPGAs face challenges in handling high-throughput data communications due to the lower operating frequencies of user logic, limiting their internal capabilities for high-speed applications such as machine learning and networking.
Innovation Solution
Implementing a sliced router architecture within the FPGA that decomposes the router into multiple slices, each with a subset of external ports, and uses inter-slice communication to achieve full router functionality while reducing wire density and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a traditional router is implemented in FPGA user logic, then routing functionality is achieved, but the operating frequency is limited due to the lower speed of user logic compared to high-frequency interfaces
Solution Approach 1:
The router is divided into multiple slices, each handling a subset of external ports. Each slice contains input blocks, output blocks, and routing logic that operates independently at high frequency. This segmentation allows the routing function to be distributed across multiple high-speed parallel units rather than implemented as a single complex sequential router in user logic.
2Loss of time
If wire density is reduced in the sliced router, then latency is reduced, but the complexity of inter-slice communication increases
Solution Approach 1:
Inter-slice communication is achieved by transitioning to a different spatial dimension within the FPGA fabric, utilizing the three-dimensional architecture of modern FPGAs. The slices are arranged and connected in a way that exploits vertical and horizontal routing resources, allowing short-latency communication paths that reduce wire density while managing complexity through structured interconnect design.
Data Source
AI summary
A sliced router decomposes a router into a plurality of slices. Each slice has a subset of the input and output ports of the router. One or more of the slices may communicate with a network access point. Adjacent slices communicate with each other. In some example embodiments, there are dedicated physical channels between each slice and each adjacent slice for traffic coming in on or going out on ports of other slices. Within a slice, traffic may be arbitrated onto upstream or downstream channels going to the same output port. Each slice contains one or more crossbars, allowing data received on any input port to be routed to any output port of the slice. The crossbar of each slice is substantially smaller than the crossbar that would be used by a unified router.