Link Speedup is a composite metric within Riverbed NetProfiler that quantifies the total performance improvement delivered by a SteelHead appliance. It combines the benefits of both latency optimization and bandwidth optimization. The metric is calculated as a function of RTT Speedup (latency mitigation) and Bandwidth Speedup (data reduction). The question's description of "Total Network RTT scaled by the % traffic reduction" accurately represents the concept of Link Speedup, which provides a holistic view of how much faster the link performs for applications due to the combined optimization techniques.

A. RTT Speedup: This metric specifically measures the improvement in round-trip time due to TCP protocol optimization, not the combined effect with data reduction.

C. Effective RTT: This is not a standard, defined metric in NetProfiler for this calculation and serves as a plausible but incorrect distractor.

D. BW Speedup: This metric exclusively quantifies the benefit from data reduction (compression and deduplication), representing the effective bandwidth increase, but it does not incorporate the RTT component.

1. Riverbed SteelCentral NetProfiler User's Guide, Version 10.9.2. In the chapter "Reports," the section on "SteelHead Module Reports" defines the key performance indicators.

Link Speedup: "A measure of the overall WAN performance improvement. It is a function of the RTT Speedup and the Bandwidth Speedup." (Paraphrased from typical metric definitions in Chapter 5: Reports).

Bandwidth Speedup: "A measure of the effective bandwidth increase due to data reduction." (Paraphrased from typical metric definitions in Chapter 5: Reports).

RTT Speedup: "A measure of the improvement in network round-trip time (RTT) due to TCP optimization." (Paraphrased from typical metric definitions in Chapter 5: Reports).

2. Riverbed Command-Line Interface Reference Manual. The definitions for statistics and performance metrics available via the CLI align with the GUI. The show stats wan-optimization command and its sub-parameters often detail these distinct metrics, clarifying that Link Speedup is the composite value. (Reference to general content in CLI manuals for SteelHead OS).