Networking - SAI _ Switch Abstraction Interface - Sub-Project - (2026-04-16)

Why It Matters

Integrating OTN into SAI gives operators a single, open‑source stack for both packet and optical layers, accelerating deployment of unified, software‑defined data‑center interconnects.

Key Takeaways

• SAI adopts experimental OTN objects for optical amplifiers and attenuators
• Phase‑one introduces minimal OTN support; later phases add transponders and OCMs
• Decimal values handled via integer+position tag to avoid SAI type changes
• Separate OTN code paths keep switch and optical logic isolated
• Unified SONiC‑based orchestration enables multi‑layer SDN control

Summary

The meeting presented a proposal to extend the Switch Abstraction Interface (SAI) with optical transport network (OTN) support. Alibaba’s Wan and Molex’s Jimmy outlined how the Sonic OTM work group plans to integrate OTN components—starting with optical amplifiers and attenuators—into SAI as experimental objects, mirroring OpenConfig YANG models. Key insights include the three‑phase rollout: Phase 1 adds basic amplifier and attenuator objects; Phase 2 will bring in OCM, OTDR, WSS, and APS; Phase 3 targets full transponder functionality. To avoid disrupting existing SAI IP objects, the OTN definitions are isolated via the experimental namespace and introduced through extension mechanisms rather than core code changes. A novel integer‑plus‑position tag enables decimal precision without altering SAI’s data‑type system. Notable details: the proposal reuses OpenConfig attribute definitions, reducing debate over field selection, and implements a new switch type “OTN” to route OTN‑specific logic. Code changes are confined to dedicated OTN files—flex‑counter, config‑manager, and ultra‑agent—ensuring runtime parity between traditional switches and OTN devices. The pull request, reviewed and approved after addressing range checks for the position tag, now awaits final merge. Implications are significant: a unified SONiC‑based control plane can orchestrate both packet and optical layers, offering vendors a common development base and expanding SONiC’s influence into the broader network domain. This paves the way for multi‑layer SDN controllers and tighter integration of data‑center interconnects.

Original Description

Public call recording of Networking - SAI _ Switch Abstraction Interface sub-project.