CUBIC Local Loss Recovery vs. BBR on (Satellite) Internet Paths
Jörg Deutschmann, Kai-Steffen Hielscher, Reinhard German · 2023
Paths with high delay and packet loss are problematic for transport protocols, especially when loss-based congestion control algorithms are used. Our topology of interest is a geostationary satellite path (round trip time approx. 600 ms) with additional packet loss, which could be caused by a lossy wireless local area network. In geostationary satellite networks, Performance Enhancing Proxies split TCP connections to improve performance, but this is not possible in case of encrypted transport protocols (VPNs, QUIC). This motivates the use of local loss recovery, i.e., avoiding packet loss on specific path segments. We briefly discuss related concepts, architectures, and protocols. We then evaluate local loss recovery using a TCP tunnel on the lossy link. By means of a simple emulation setup, we demonstrate that local loss recovery has great performance benefits if CUBIC is used. It is also shown that BBR works well for high-delay and lossy paths even without local loss recovery.