On Wed, Oct 29, 2014 at 7:04 PM, Ben Sjoberg <bensjoberg@gmail.com> wrote:
That 3Mb difference is probably just packet overhead + congestion
Yes... however, that's actually an industry standard of implying higher performance than reality, because end users don't care about the datagram overhead which their applications do not see they just want X megabits of real-world performance, and this industry would perhaps be better off if we called a link that can deliver at best 17 Megabits of Goodput reliably a "15 Megabit goodput +5 service" instead of calling it a "20 Megabit service" Or at least appended a disclaimer *"Real-world best case download performance: approximately 1.8 Megabytes per second" Subtracting overhead and quoting that instead of raw link speeds. But that's not the industry standard. I believe the industry standard is to provide the numerically highest performance number as is possible through best-case theoretical testing; let the end user experience disappointment and explain the misunderstanding later. End users also more concerned about their individual download rate on actual file transfers and not the total averaged aggregate throughput of the network of 10 users or 10 streams downloading data simultaneously, or characteristics transport protocols are concerned about such as fairness.
control. Goodput on a single TCP flow is always less than link bandwidth, regardless of the link.
--- -JH