SMaRTT: Sender-based Marked Rapidly-adapting Trimmed & Timed Transport

Understand

With the rapid growth of artificial intelligence (AI) workloads in datacenters, the Ultra Ethernet Consortium (UEC) has defined a new high-performance transport layer to deliver the required performance at scale.

• A core component of this new standard is the Network Signal-based Congestion Control (NSCC) algorithm.
• This paper presents SMaRTT, the algorithm that forms the basis of the UEC NSCC specification.
• SMaRTT is a sender-based congestion control algorithm that systematically combines delay, Explicit Congestion Notification (ECN), and optional packet trimming into a cohesive state machine for fast, fair and precise window adjustments with seamless multipath support.