NDT-DEV email list created

Revision: 594
Author:   

Date:     Fri Sep  2 06:12:11 2011
Log:      Updated Duplex Mismatch Detection section according to the  
received feedback.
http://code.google.com/p/ndt/source/detail?r=594

Modified:
 /wiki/NDTTestMethodology.wiki

=======================================
--- /wiki/NDTTestMethodology.wiki       Fri Sep  2 05:44:31 2011
+++ /wiki/NDTTestMethodology.wiki       Fri Sep  2 06:12:11 2011
@@ -171,23 +171,29 @@

 A duplex mismatch is detected by the Old Duplex-Mismatch algorithm when  
all of the following conditions are met:
  * The  
[NDTTestMethodology#'Congestion_Limited'_state_time_share 'Congestion  
Limited' state time share] *is greater than 90%*
- * The [NDTTestMethodology#Speed_estimate speed estimate] *is greater than  
2000000 bits per second*
+ * The [NDTTestMethodology#Speed_estimate speed estimate] *is greater than  
2Mibps*
  * The number of segments transmitted containing at least some  
retransmitted data *is greater than 2 per second*
  * The maximum slow start threshold, excluding the initial value, *is  
greater than 0*
  * The cumulative time of the expired retransmit timeouts RTO *is greater  
than 1% of the total test time*
- * (link > 2) (*WARNING: this condition is always true*)
+ * The link type detected by the  
[NDTTestMethodology#Link_Type_Detection_Heuristics Link Type Detection  
Heuristics] is not a wireless link
  * The throughput speed measured during the MID test (with a limited CWND)  
*is greater than* the throughput speed measured during the S2C test
- * The multi-test mode must be disabled (so the `-m, --multiple` options  
cannot be set)
  * The throughput speed measured during the C2S test *is greater than* the  
throughput speed measured during the S2C test

 If all of the above conditions are met except the last one, then the NDT  
assumes that a new duplex mismatch detection algorithm discovers the  
problem.

 The new duplex mismatch detection algorithm also discovers the problem  
when all of the following conditions are met:
- * The throughput speed measured during the S2C test *is greater than  
50000000 bits per second*
- * The [NDTTestMethodology#Web100_measured_speed web100 measured speed]  
*is less than 5000000 bits per second*
+ * The throughput speed measured during the S2C test *is greater than 50  
Mbps*
+ * The [NDTTestMethodology#Web100_measured_speed web100 measured speed]  
*is less than 5 Mbps*
  * The [NDTTestMethodology#'Receiver_Limited'_state_time_share 'Receiver  
Limited' state time share] *is greater than 90%*
  * The proportion of the number of multiplicative downward congestion  
window adjustments to the total number of segments sent *is less than 1%*

+==== Known limitations ====
+
+The Old Duplex-Mismatch algorithm does not work with multiple simultaneous  
tests. In order to enable this algorithm, the multi-test mode must be  
disabled (so the `-m, --multiple` options cannot be set).
+
+The condition "The link type detected by the  
[NDTTestMethodology#Link_Type_Detection_Heuristics Link Type Detection  
Heuristics] is not a wireless link" is always fulfilled, because the Duplex  
Mismatch Detection heuristic is run before the Link Type Detection  
heuristic.
+
+
 === Link Type Detection Heuristics ===

 The following link type detection heuristics are run only when there is no  
duplex mismatch condition detected and the  
[NDTTestMethodology#Web100_measured_speed web100 measured speed] is the  
same or smaller than the [NDTTestMethodology#Speed_estimate speed estimate]  
(which is a correct situation).
@@ -197,7 +203,7 @@
 The link is treated as a DSL/Cable modem when all of the following  
conditions are met:
  * The cumulative time spent in the 'Sender Limited' state *is less than  
0.6 ms*
  * The number of transitions into the 'Sender Limited' state *is 0*
- * The [NDTTestMethodology#Web100_measured_speed web100 measured speed]  
*is less than 2000000 bits per second*
+ * The [NDTTestMethodology#Web100_measured_speed web100 measured speed]  
*is less than 2 Mbps*
  * The [NDTTestMethodology#Web100_measured_speed web100 measured speed]  
*is less than* [NDTTestMethodology#Speed_estimate speed estimate]

 ==== IEEE 802.11 (!WiFi) ====
@@ -205,8 +211,8 @@
 The link is treated as a wireless one when all of the following conditions  
are met:
  * The heuristic for DSL/Cable modem link *gives negative results*
  * The cumulative time spent in the 'Sender Limited' state *is 0 ms*
- * The [NDTTestMethodology#Web100_measured_speed web100 measured speed]  
*is less than 5000000 bits per second*
- * The [NDTTestMethodology#Speed_estimate speed estimate] *is greater than  
52428800 bits per second*
+ * The [NDTTestMethodology#Web100_measured_speed web100 measured speed]  
*is less than 5 Mbps*
+ * The [NDTTestMethodology#Speed_estimate speed estimate] *is greater than  
50 Mibps*
  * The number of transitions into the 'Receiver Limited' state *is the  
same* as the number of transitions into the 'Congestion Limited' state
  * The [NDTTestMethodology#'Receiver_Limited'_state_time_share 'Receiver  
Limited' state time share] *is greater than 90%*

@@ -214,9 +220,9 @@

 The link is treated as an Ethernet link (Fast Ethernet) when all of the  
following conditions are met:
  * The heuristics for !WiFi and DSL/Cable modem links *give negative  
results*
- * The [NDTTestMethodology#Web100_measured_speed web100 measured speed]  
*is less than 9500000 bits per second*
- * The [NDTTestMethodology#Web100_measured_speed web100 measured speed]  
*is greater than 3000000 bits per second*
- * The S2C throughput test measured speed *is less than 9500000 bits per  
second*
+ * The [NDTTestMethodology#Web100_measured_speed web100 measured speed]  
*is less than 9.5 Mbps*
+ * The [NDTTestMethodology#Web100_measured_speed web100 measured speed]  
*is greater than 3 Mbps*
+ * The S2C throughput test measured speed *is less than 9.5 Mbps*
  * The proportion of the number of multiplicative downward congestion  
window adjustments to the total number of segments sent *is less than 1%*
  * The proportion of the duplicate ACKs received to the overall number of  
valid pure ACKs received *is less than 3.5%*

@@ -304,7 +310,7 @@
  * *!DataBytesOut* - The number of octets of data contained in transmitted  
segments, including retransmitted data.
  * *!TotalTestTime* - [NDTTestMethodology#Total_test_time Total test time]

-The web100 measured speed is kept in mbits per second.
+The web100 measured speed is kept in Mbps.

 === Packet loss ===