Working on adding the notes and summarizing the metrics discussions

draft-iab-mnqeu-report.md

@@ -275,6 +275,9 @@ informative:
       - ins: S. Cheshire
     seriesinfo: https://www.iab.org/wp-content/IAB-uploads/2021/09/Internet-Score-2.pdf
 
+  ping:
+    title: "PING(8)"
+
 --- abstract
 
 The Measuring Network Quality for End-Users workshop was held
@@ -433,6 +436,50 @@ of the Internet.  The need for improvements to latency and its
 measurements was heavily discussed, especially for certain classes of
 users such as live, collaborative content and gaming.
 
+### Latency considerations
+
+End-to-end latency is the time it takes for a particular segment to traverse
+the entire network path from the user to their destionation. The end-to-end
+latency comprises several components:
+
+1. The propagation delay, which reflects the path distance and the individual
+   link technologies (e.g. fibre vs satellite). The propagation doesn't depend
+   on the utilization of the network, to the extent that the network path
+   remains constant.
+2. The buffering delay, which reflects the time segments spend in the memory of
+   the network equipment that connect the individual network links, as well as
+   in the memory of the transmitting endpoint. The buffering delay depends on
+   the network utilization, as well as on the algorithms that govern the queued segments.
+3. The transport protocol delays, which reflects the time spent in
+   retransmission and reassembly, as well as the time spent when the transport
+   is "head-of-line blocked."
+4. Some of the workshop sumbissions have explicitly called out the application
+   delay, which reflects the inefficiencies in the application layer.
+
+### Idle latency vs. working latency.
+
+Tradionally, end-to-end latency is measured with tools such as {{ping}}, as
+well as with services such as {{speedtest}} or {{ookla}}.
+Such measurements are typically performed when the network is idle, and as a
+result, such measurements reflect mostly the propagation delay.
+
+A different way to measure end-to-end latency is to perform the test when the
+network is not idle, but in its typical working conditions.
+
+The workshop participants used the term "Idle latency" when referring to the
+subject of the former measurement methods, and "Working latency" when referring
+to the latter.
+
+### Metrics - conclusions
+
+Through the course of the workshop, the following statements have emerged:
+
+1. There's a dramatic difference between the idle latency and the working
+   latency measurements.
+2. The variance in idle latency is not high, while the working latency varies
+   wildly.
+3. Most of the tools to measure end-to-end latency focus on the idle latency.
+
 ## Cross-layer considerations
 
 In the Cross-layer section participants presented material and discussed