Packet Loss

Wikipedia

Having noticed that my data usage was climbing while my actual computer and network usage was decreasing, I tried to ascertain if Telecom's data accounting was in fact counting packets that were dropped within their network. This page contains evidence that leads me to conclude the affirmative, that Telecom can charge it's customers up to four times for a file they upload through a DSL connection. I believe Telecom are aware of this and it is the reason that they doubled the data allowance on some broadband plans.

The email below confirms that all data between modem and DSLAM is counted.

The tests below show that packet loss can cause uploaded files to to be transmitted four times (initial transmition 100% + retransmitted segments 300% = 400%). Thus, if any routers after the DSLAM/ISAM you are connected to drop packets, you may be debited 4GB for every 1GB that you are uploading. The months of data on the TRACERTs page shows that the major point of packet loss for Telecom's broadband users are nodes within it's own GGIS network.

Test # 1 (HTTP)
WinXP on Intel, using FrontPage2k to upload 64MB (67,200,800 bytes) from 10:57am to 12:05pm Sunday, 14th October 2007 giving a real-world average speed of 16KB (16,470.78 bytes) per second.

NETSTAT values immediately prior to uploading 64MB file
NETSTAT values immediately after uploading 64MB file
Before upload
Segments Sent               = 553 
Segments Retransmitted   =  46   

After upload
Segments Sent               = 16968 
Segments Retransmitted  = 49306 
Therefore 
Segments Sent                = 16968 - 553 = 16415 
Segments Retransmitted  = 49306 -  46 = 49260
300 % Retransmitted.

 

Test # 2 (FTP)
Win98SE on AMD, using SimplyCoolFTP to upload 64MB (67,200,800 bytes) from 4:30pm to 5:57pm Sunday, 14th October 2007 giving a real-world average speed of 12.5KB (12,873.72 bytes) per second.

NETSTAT values immediately prior to uploading 64MB file
NETSTAT values immediately after uploading 64MB file
Before upload
Segments Sent               = 38 
Segments Retransmitted   =  0   

After upload
Segments Sent               = 49408 
Segments Retransmitted  =  4733 
Therefore 
Segments Sent                = 49408 - 38 = 49370 
Segments Retransmitted  =  4733 -  0 =   4733
9.5 % Retransmitted.

 


    DSLAM/port changed 27/10/07

Test # 4 (HTTP)
WinXP on Intel, using FrontPage2k to upload 35MB (36,844,600 bytes) from 10:05am to 10:45am Tuesday, 30th October 2007 giving a real-world average speed of 14.99KB (15,352 bytes) per second.

NETSTAT values immediately prior to uploading 35MB file
NETSTAT values immediately after uploading 35MB file
Before upload
Segments Sent               = 92 
Segments Retransmitted   =  47   

After upload
Segments Sent               =   9102
Segments Retransmitted  =  27314 
Therefore 
Segments Sent               =    9102 - 92 =   9010
Segments Retransmitted   =  27314 - 47 = 27267
302.6 % Retransmitted.

 

 

Test # 5 (HTTP)
WinXP on Intel, using FrontPage2k to upload 34.9 MB (36,647,955 bytes) from 12:05pm to 12:45pm Monday, 5th November 2007 giving a real-world average speed of 14.91KB (15,270 bytes) per second.

NETSTAT values immediately prior to uploading 34.9MB file
NETSTAT values immediately after uploading 34.9MB file
Before upload
Segments Sent               = 6892 
Segments Retransmitted   =   308   

After upload
Segments Sent               =  15848
Segments Retransmitted  =  27225 
Therefore 
Segments Sent               =  15848 - 6892 =  8956
Segments Retransmitted   =  27225 -  308 = 26917
300.5 % Retransmitted.