Source Routing in Ethernet Fabric Switches
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Solution Overview
Problem
As fabric networks grow larger, look-up tables in switching processors experience increased latency due to vast amounts of data, necessitating a method to reduce overhead and latency in fabric switches.
Innovation Solution
Implementing a system with a switch controller that configures and determines paths through a network fabric, creating a source-routing table to store paths between hosts, allowing packets to be routed using source-routing information stored in packet headers, thereby reducing reliance on traditional look-up tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional look-up tables are used in fabric switches to determine egress ports, then routing functionality is provided, but latency increases as network size grows
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing optimal paths in source-routing tables before packet transmission. The switch controller determines and configures paths through the network fabric in advance, allowing fabric switches to simply follow pre-determined routes without performing real-time look-ups, thereby eliminating latency associated with dynamic routing decisions
Solution Approach 2:
The patent introduces a switch controller as an intermediary that centralizes path determination logic. Rather than having each fabric switch independently query large look-up tables, the controller acts as a mediator that pre-computes paths and distributes them to switches, reducing the computational burden and latency at individual switching nodes
2Ease of operation
If look-up tables are used to store routing information, then packet forwarding is enabled, but device complexity increases
Solution Approach 1:
The patent extracts the complex path determination logic from individual fabric switches and consolidates it into a centralized switch controller. This removes the complexity of managing large look-up tables from each switch, allowing individual switches to operate with simpler source-routing tables that only store pre-computed paths rather than performing real-time routing decisions
Solution Approach 2:
The patent segments the routing function into two distinct components: a centralized controller that handles complex path computation and a distributed switching fabric that executes simple packet forwarding based on pre-determined paths. This segmentation reduces the complexity burden on individual switches while maintaining efficient packet forwarding capability
Data Source
AI summary
In one embodiment, a system includes a network fabric having a plurality of fabric switches interconnected in the network fabric and a switch controller having logic adapted to configure the network fabric, determine one or more paths through the network fabric between any two hosts connected thereto, and create a source-routing table to store the one or more paths through the network fabric between any two hosts connected thereto. In another embodiment, a method includes receiving or creating a packet using a NIC of a host connected to a network fabric having a plurality of fabric switches interconnected therein, determining a path through the network fabric by consulting a source-routing table stored to the host, storing source-routing information to a packet header for the packet, the source-routing information including the path, and sending the packet to a first device or hop indicated by the path in the source-routing information.