DENT SAI Integration

Author: Sandeep (Amazon), Carl Roth (Amazon), Larry Ho (Edgecore) Collection: 2023 Global Summit - Networking

Summary

The DENT project, a Linux Foundation initiative focused on enterprise and edge networking, is integrating SAI (Switch Abstraction Interface) as an alternative hardware abstraction layer alongside its existing SwitchDev approach. Previously announced at the Prague OCP Regional Summit earlier in 2023, this integration introduces the Ethernet Switch Manager (ESM) -- a new component with a user-space agent and kernel module that bridges Linux kernel networking events to SAI API calls. The goal is to attract more ASIC vendors who prefer the SAI approach over SwitchDev firmware blobs, while preserving DENT's Linux-native networking model using standard tools like iproute2.

DENT OS, originally contributed by Amazon, is designed for enterprise environments including retail stores, corporate campuses, and IoT gateway deployments. It runs on native Linux using Yocto, ONLP, and SwitchDev. The project has premier members including Amazon, Delta, Edgecore, and Marvell, with general members Keysight, BISDN, Bootlin, Micas, PLVision, Sartura, and Wistron. The SAI integration targets a beta release in February 2024 with feature parity to DENT v2, GA release in Q1 2024, supporting Marvell AC5x and Broadcom Trident 3X-2 chipsets. DENT also positions itself as a potential ONL (Open Network Linux) replacement.

The ESM architecture implements a custom SwitchDev driver in kernel space and a user-space service with per-feature modules for handling network events. It dynamically links the appropriate vendor SAI module and also allows direct vendor SDK calls when SAI attributes are insufficient. Signal flow diagrams demonstrate L3 forwarding (iproute2 to kernel to ESM to SAI to ASIC) and L2 FDB learning (ASIC event to SAI callback to ESM to kernel notification).