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[204.195.96.226]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-65cfed58446sm8574467a12.74.2024.05.22.08.59.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 May 2024 08:59:29 -0700 (PDT) Date: Wed, 22 May 2024 08:59:27 -0700 From: Stephen Hemminger To: Kenneth Porter via Bloat Cc: Kenneth Porter Message-ID: <20240522085927.32b82e93@hermes.local> In-Reply-To: <4223FB1D3EC8265F9E30D997@[192.168.11.128]> References: <4223FB1D3EC8265F9E30D997@[192.168.11.128]> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Bloat] A Transport Protocol's View of Starlink X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 May 2024 15:59:31 -0000 On Wed, 22 May 2024 06:16:17 -0700 Kenneth Porter via Bloat wrote: > This technical paper on Starlink by the chief scientist at APNIC crossed my > feed this week. [I thought I'd share it to the Starlink list here but my > application to join that list seems to have gotten stuck so I'll share it > here for now.] > > > > >From the end of the paper: > > > While earlier TCP control protocols, such as Reno, have been observed to > > perform poorly on Starlink connections, more recent TCP counterparts, > > such as CUBIC, perform more efficiently. The major TCP feature that makes > > these protocols viable in Starlink contexts is the use of Selective > > Acknowledgement [11], that allows the TCP control algorithm to > > distinguish between isolated packet loss and loss-inducing levels of > > network congestion. > > > > TCP control protocols that attempt to detect the onset of network queue > > formation can do so using end-to-end techniques by detecting changes in > > end-to-end latency during intermittent periods of burst, such as BBR. > > These protocols need to operate with a careful implementation of their > > sensitivity to latency, as the highly unstable short-term latency seen on > > Starlink connections, coupled with the 15-second coarse level latency > > shifts have the potential to confuse the queue onset detection algorithm. > > > > It would be interesting to observe the behaviour of an ECN-aware TCP > > protocol behaviour if ECN were to enabled on Starlink routing devices. > > ECN has the potential to provide a clear signal to the endpoints about > > the onset of network-level queue formation, as distinct from latency > > variation. It frustrates me that all research still looks primarily at Reno, rather than the congestion controls that are actually implemented in Linux and Windows which are used predominately on the Internet.