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warning regarding pppoe mode & 2-8AM free usage bsnl usage calculation system is doing something very fishy & i am sure of it
now.i have taken observations over a period of 8 days to be absolutely sure about this.i have network bandwidth monitoring application installed on my system & i was using bridge mode until 11th april after which i had to change to pppoe mode because of some problems in my system.i first noticed these anamolies on 13th april & initially dismissed them as one time bad luck but later realised these are not one time errors but are regular in nature.
on 12th april
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as you can see from 00-01:59AM usage reported by networx & bsnl portal is almost same but then according to portal i dl 75781kb or 74mb data from 8:00-8:45AM but according to networx i dl 11.99mb which is expected(you can dl ~12mb per minute at avg speed ~200KBps) because being 1st time using pppoe mode i realised a minute later that i had to stop dl manually because before i used batch file to disconnect as my dl manager's scheduler function works incorrectly.now here is the interesting this which proves beyond doubt that bsnl is wrong.i was dl from a http link using dl manager getting an avg speed of 200KBps which is expected but
according to bsnl i dl only 99631kb or 97mb of data from 7:42-8:00AM which is wrong.however if you add this 97mb+74mb you get 171mb of data which closely matches with both networx(155.81+11.99=167.8mb) & dl manager data with avg speed~190KBps.
on 13th april
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from 00:01-02:00AM usage according to networx is 17.37mb while bsnl shows 86.18mb from 00:20-2:00AM.similarly bsnl shows from 8AM to 1:52PM data transfer of 98.25mb while networx shows 14.77mb.once again interesting thing is from 2-8AM bsnl shows total data transfer 4486mb while network shows it as 4543.45mb.if we add total data transfer between 2-8AM & 8AM to 2PM according to networx(4543.45+17.37)we get 4560.82mb while for bsnl(4486+98.25)we get 4584.25mb which is close to networx value for this period.
on 14th april
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from 01:00-2:00AM networx shows 1.94mb while while bsnl shows(21+1646+50707)51.15mb.between 2-8AM networx shows total data transfer as 3913.52mb while bsnl shows 3885mb.the difference is 28.52mb which is almost half of 51.15mb.at an avg speed of 190KBps dl 51.15mb will take ~4.5 minutes so for bsnl reading to be correct my system clock has to be 5 minutes ahead of bsnl time which is not the case because upto 12th of april i was using bridge mode & by matching my disconnection time with bsnl entries my system clock is ~20sec ahead of bsnl time.also even if we assume that somehow my system clock get forwarded by 5 minutes then i will be seeing additional dl of 60-100mb each day outside of 2-8AM because i start/stop dl only ~30-40sec difference at 2 & 8AM according to my system time but this is not the case so it can be ruled out that my system clock has suddenly changed.
on 15th april
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after 3 straight days of such observations i finally decided to restart the modem at 80-90 seconds before 2AM such that when modem connects it will do so after 2AM only as per bsnl clock.as it can be seen this works perfectly.bsnl portal show disconnection at 01:58:33AM & reconnection at 02:00:13AM with no unusual entry for time before 2AM.however i couldn't restart the modem at ~8AM due to some reason & when i finally restarted it at ~8:01:40AM i got an entry of 24.73mb while networx shows 0.07mb which is expected because i was dl torrents at that time & i have enabled the inbuilt scheduler in utorrent which stops torrents at 8AM.even if we assume that some data transfer take place while speed goes down from 210KBps to 1KBps it still is not enough to make a large data transfer of 24.73mb.
on 16th april
http://img545.imageshack.us/img545/1778/16aprportal.png
http://img845.imageshack.us/img845/7...aprnetworx.png
i fell asleep at ~1:15AM & couldn't restart modem at 1:58AM as i planned & as expected there is 57.7mb transfer while networx shows 2.59mb.from 2-8AM bsnl shows total transfer 4107mb while networx shows 4178.64mb which is again close to bsnl's 57.7+4107=4164.7mb meaning bsnl is adding some amount of dl started at the beginning of 2-8AM period in charged usage if modem is continuously on a few seconds before & after 2AM according to their time.again from 8-8:01AM bsnl shows 14.64mb transfer while networx show nothing because out of frustration i switched off the modem at ~8AM & again i was dl torrent so it was not possible to transfer 14.64mb in 1 minute & that too when i switched off the modem.a probable reason for this according to me is given at the end of post.
on 17th april no problem as i restarted the modem at ~2AM & 8AM.
on 18th april an interesting thing happened.i was using the pc in safe mode & scheduler doesn't work in safe mode so my modem reboot script didn't worked but i only realised it after 1 minute past 8AM.but this time there was a normal entry of 1940kb which should be ideally there.
on 19th april
http://img263.imageshack.us/img263/8619/19aprportal.png
http://img864.imageshack.us/img864/1...aprnetworx.png
i started my pc at ~3:40AM so no problem there.however at 8AM again because of safe mode i had to manually double click my modem reboot script so it was a little late than 8AM but again i was using utorrent with scheduler so as expected network shows 0.56mb transfer while again as expected bsnl shows 26.14mb.this is similar to case on 15th & 16th april with utorrent scheduler.
as i mentioned earlier i have a theory regarding this.when i was searching for speed optimization i came across a very useful site:
Argonne National Laboratory NDT server
this site does a series of test to check any network factors factors reducing the max achievable speeds & here i found out that packet queuing is ~90% for my bsnl connection.i checked multiple times over 3 days & it was always ~90%.here is some info about packet queuing :
Background
i think that in pppoe mode even after the modem is restarted or you stop dl a few seconds before 8AM the requests you have already sent for data results in a queue of data packets at bsnl's end & their system counts them as dl done during the after 8AM slot even if your pc/modem was off at that instant.it probably doesn't happen in bridge mode because of the way xp communicates to bsnl's servers through modem while in pppoe mode modem running some custom OS communicates with bsnl servers.Traffic coming inbound on your ADSL modem is queued in much the same way as outbound traffic, however the queue resides at your ISP. Because of this, you probably don't have direct control of how packets are queued or which types of traffic get preferential treatment.
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