NDT-DEV email list created

Revision: 445
Author:   

Date:     Thu Aug  4 02:22:07 2011
Log:      Feedback based fixes in the first four sections.
http://code.google.com/p/ndt/source/detail?r=445

Modified:
 /wiki/NDTProtocol.wiki

=======================================
--- /wiki/NDTProtocol.wiki      Tue Aug  2 03:37:04 2011
+++ /wiki/NDTProtocol.wiki      Thu Aug  4 02:22:07 2011
@@ -4,7 +4,7 @@

 == Abstract ==

-Network Diagnostic Tool (NDT) is a client/server program that provides  
network configuration and performance testing to a user's computer. It uses  
a well-defined protocol to provide a reliable communication link between  
its subcomponents. This protocol documentation is sufficient to allow  
outside parties to write compatible NDT clients without consulting the NDT  
source code. This documentation contains a state transition diagrams  
detailing the various states that the components (both server and client)  
can be in, and the valid messages that can or will be transmitted or  
received in those states.
+The Network Diagnostic Tool (NDT) is a client/server program that provides  
network configuration and performance testing to a user's computer. It uses  
a well-defined protocol to provide a reliable communication link between  
client and server. This protocol documentation is sufficient to allow  
outside parties to write compatible NDT clients without consulting the NDT  
source code. This documentation contains a state transition diagrams  
detailing the various states that the components (both server and client)  
can be in, and the valid messages that can or will be transmitted or  
received in those states.

 == Table of Contents ==

@@ -12,9 +12,9 @@

 == Introduction ==

-Several studies have shown that the majority of network performance  
problems occur in or near the users’ desktop/laptop computer.  These  
problems include, but are not limited to, duplex mismatch conditions on  
Ethernet/FastEthernet links, incorrectly set TCP buffers in the user’s  
computer, or problems with the local network infrastructure. NDT seeks to  
determine why a network connection exhibits certain performance  
characteristics. In addition to measuring the familiar upload and download  
speeds of a user's connection, NDT also performs tests that can assess  
factors such as latency, packet loss, congestion, bad cables, and  
bottlenecks on the end-to-end path from client to server.
-
-NDT popularity has grown in recent years, which led to an increased  
interest from the developers community around the world. People started to  
integrate NDT with their systems using different approaches, like adding  
Web Developer's API to Web based (java applet) client and writing new  
mobile (Android based) client.
+Several studies have shown that the majority of network performance  
problems occur in or near the users’ desktop/laptop computer.  These  
problems include, but are not limited to, duplex mismatch conditions on  
Ethernet/FastEthernet links, incorrectly set TCP buffers in the local  
network infrastructure (e.g. first hop switch/router, hubs, etc.) and bad  
or dirty cables. NDT seeks to determine why a network connection exhibits  
certain performance characteristics. In addition to measuring the familiar  
upload and download speeds of a user's connection, NDT also performs tests  
that can assess factors such as latency, packet loss, congestion, bad  
cables, out of order delivery and bottlenecks on the end-to-end path from  
client to server (on either side of the connection).
+
+NDT popularity has grown in recent years, which led to an increased  
interest from the developers community around the world. People started to  
integrate NDT with their systems using different approaches, like adding  
Web Developer's API to a Web based (java applet) client and writing a new  
mobile (Android based) client.

 NDTP is allowing outside parties to easily extend both NDT server and  
client parts and write compatible clients in new languages that will be  
able to communicate with the publicly available Measurement Lab servers.

@@ -22,17 +22,17 @@

 === Relationship of Tests and Control Protocols ===

-NDTP actually consists of two inter-related sets of protocols:  
NDTP-Control and NDTP-Tests. NDTP-Control is used to initiate, start, and  
stop test sessions and to fetch their results, whereas NDTP-Tests is a set  
of smaller sub-protocols used to exchange test packets between two  
measurement nodes.
+NDTP actually consists of two inter-related sets of protocols:  
NDTP-Control and NDTP-Tests. NDTP-Control is used to initiate, start, and  
stop test sessions and to fetch their results, whereas NDTP-Tests is a set  
of smaller sub-protocols concentrated on testing specific network  
performance problems.

 NDTP-Tests consists of five smaller sub-protocols: Middlebox test, Simple  
firewall test, C2S throughput test, S2C throughput test and META test.  
These tests are completely independent from each other and can be run in  
any order. Moreover, new NDTP-Tests protocols can be easily created and  
integrated into the existing tests ecosystem.

-NDTP-Control is designed to support the negotiation of test sessions and  
results retrieval in a straightforward manner. At session initiation, there  
is a negotiation of the test suite and session start time. Moreover, server  
version is being verified to discover the possibility of incompatibilities.  
Additionally, NDTP-Control defines an exact message format, which greatly  
increase the general protocol reliability and allows other NDTP-Tests  
protocols to communicate in a convenient and secure fashion.
-
-We believe that NDTP-Control protocol can effectively be used to implement  
not only new types of clients, but also can be treated as a generic  
framework to create and combine with each other completely new NDTP-Tests  
protocols.
+NDTP-Control is designed to support the negotiation of test sessions and  
results retrieval in a straightforward manner. At session initiation, there  
is a negotiation of the test suite and session start time. Moreover, server  
version is being verified to discover the possibility of incompatibilities.  
Additionally, NDTP-Control defines an exact message format, which greatly  
increase the general protocol reliability and allows other NDTP-Tests  
protocols to communicate in a convenient and more structured fashion.
+
+NDTP-Control protocol can effectively be used to implement not only new  
types of clients, but also can be treated as a generic framework to create  
and combine with each other completely new NDTP-Tests protocols.

 === Logical Model ===

-We can distinguish several different roles on both NDTP-Control and  
NDTP-Tests levels. Specifically, we define the following:
+Several different roles on both NDTP-Control and NDTP-Tests levels can be  
distinguished. Specifically, the following ones should be highlighted:

 || *Role* || *Description* ||
 || Session-Sender || The sending endpoint of a NDTP-Tests session. ||
@@ -40,9 +40,9 @@
 || Server || An end system that manages NDTP-Control and NDTP-Tests  
sessions, performs the specific tests needed to determine what problems, if  
any, exist. The server process then analyzes the test results and returns  
these results to the client. ||
 || Client || An end system that initiates requests for NDTP-Tests  
sessions, triggers the start of a set of sessions and receives tests  
results. ||

-Different logical roles can be played by the same host. For example Server  
machine is a Session-Sender in the S2C throughput test, while it is a  
Session-Receiver in the C2S throughput test.
-
-For example, please look at the figures describing two main NDTP-Tests  
protocols:
+Different logical roles can be played by the same host. For example the  
Server machine is a Session-Sender in the S2C throughput test, while it is  
a Session-Receiver in the C2S throughput test.
+
+Please look at the figures describing two main NDTP-Tests protocols:

  * C2S throughput test

@@ -68,7 +68,7 @@

 As described above, NDTP consists of two inter-related sets of protocols:  
NDTP-Control and NDTP-Tests. Both of them are layered over TCP. The former  
is used to initiate and control test sessions and to fetch their results.  
The latter set of protocols is used to perform specific tests.

-The initiator of the test session establishes a TCP connection to a  
well-known port, 3001, on the target point and this connection remains open  
for the duration of the NDTP-Tests sessions.  A NDT server SHOULD listen to  
this well-known port.
+The initiator of the test session establishes a TCP connection to a  
well-known port, 3001, on the target point and this connection remains open  
for the duration of the NDTP-Tests sessions.  A NDT server SHOULD listen to  
this well-known port, but it MAY also choose to listen on a different port,  
because both client and server are configurable to allow this.

 NDTP-Control messages are transmitted before NDTP-Tests sessions are  
actually started, after they are completed and between particular tests  
from the performed test suite. Moreover, specific tests also use  
NDTP-Control messages to synchronise test sessions, exchange configuration  
data and additional information.