T(SN)-Ray: Gauging TAS and PSFP Delays of TSN Switches for Predictable Deterministic Networking#

Manuel Eppler (Siemens AG, University of Tuebingen) et al. (University of Tuebingen, Siemens AG, University of Kassel)

• Why: A black-box method to measure what switch datasheets never tell you: per-switch internal forwarding delays at nanosecond granularity — the numbers you need before you can compute valid TAS gate schedules or PSFP configurations at all. As switching-hardware work with an industrial-metrology flavor, it's a methodology you'd want your vendors measured with.
• What: A delay model for TSN switches plus a measurement methodology to quantify its parameters on any given switch — the first known approach to deriving these delays. Applied to switches from Kontron and Relyum, it reveals significantly different operational delays between vendors (from abstract only).
• How: Black-box gauging: carefully timed probe traffic isolates the components of switch-internal delay (queueing, gate mechanics, forwarding), fitting them to the proposed model without switch cooperation.
• Where applicable: Time-Sensitive Networking deployments — industrial Ethernet, automotive, and increasingly deterministic-Ethernet in DCs. The methodology is general (any TSN switch); the measured values are per-vendor/per-product and the results show you cannot port schedules between switches without re-gauging.