Analysis for the Adverse Effects of LEO Mobility on Internet Congestion Control

Low-earth-orbit (LEO) satellite networks (LSNs) are increasingly used to carry Internet traffic. However, the fast time-varying conditions induced by LEO mobility can significantly impair the performance of end-to-end Internet congestion control algorithms (CCAs). This document summarizes and analyzes how mobility-driven (often non- congestive) variations in capacity, delay, and loss can mislead representative classes of CCAs, using Starlink as an operational case study. In addition, this document highlights recently-validated measurement and design considerations that treat connection reconfiguration as a phase boundary observable at endpoints, which can improve the interpretation of network signals without requiring changes to the network infrastructure. This document also proposes a transport-agnostic "Path Phase Boundary" (PPB) abstraction and corresponding endpoint behavior considerations for safely using such hints across diverse CCAs. Finally, it outlines a reference endpoint probing profile that can be used to infer PPBs in a deployable, best- effort manner. The goal of this document is informational: to clarify the problem space and to inform future standardization and engineering efforts for congestion control over LSN paths.