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Data transfer and GPRS |
JLP
Joined: Apr 08, 2002
Posts: 2
From: UK
PM |
I seem to be going through my GPRS data allowance (0.5mb with Orange in the UK) at an alarming rate. Checking work emails and occasional WAP access has used 400kb already (in 3 days)...I don't read all the emails, and I thought only the headers were downloaded anyway...I've only actually read 3 or 4.
Is the data counter in a T39 a true reflection of how much actual data has been sent/received ?
Help/comments anyone ?
JLP |
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Telboy_uk
Joined: Apr 12, 2002
Posts: 8
From: Surrey
PM |
I am not sure how familiar you are with general IP protocols but at the risk of explaining something you already know here goes.
The data rate counted is for all data downloaded, even if you do not actually see it on your screen. It takes a bit of messaging backwards and forwards before you actually access your POP mail account. This wil no doubt add to the data count though would be hidden from you.
As a brief example:
When accessing a POP email account, in general you first connect to the server at the appropriate port. The server may respond in clear text as follows:
"+OK hello from popgate(2.22) "
your POP reader should then send a further request to log you in such as
"user my_mail_account_name"
to which the server will respond something like
"+OK password required"
your client will then send the password
"pass my_password"
The server may then send a response to show you that it has logged in:
"+OK maildrop ready, 2 messages (6043 octets) (2612896 6291456)"
All of this goes on behind the scenes but is still counted as data. Of course the transaction so far has merely logged you in to the Mail server. There are still more hidden data transactions needed to provide you with a list of messages and/or to download them.
Added to this, each message itself has a large header which you often do not see. Most clients suppress the full header because it just adds to confuse the reader who is only interested in the message content. However the client still receives it even if it ids not displayed and so it still counts as data.
Just to add to this data count, logging off also adds to the data count as does the initial logging on the the GPRS servers themselves. This goes into some depth so I wont bore you but think you get the gist.
As an added note..... some Company emails may attach very large headers due to the routing path they use. If the company is a large multinational, all emails may be routed via USA over many different hops. This may make the email headers very large indeed.
Added to this... the response I showed earlier once logged on to the email server was that of Yahoo and is particularly short. Some server administrators however decide to respond with very long and verbose welcome messages which most clients simply would not see.
Most server applications have been written or configured to take account of standard desktop access where it is not such a problem to have verbose responses. As GPRS (pay for data count) type services become more common, people will start to truncate these responses .....I hope.
Saying that my explanation has become rather verbose  .... but hope it helps.
Terry
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JLP
Joined: Apr 08, 2002
Posts: 2
From: UK
PM |
Thanks for this - I now understand why there is so much data flowing !
JLP |
ferrarista44
Joined: Jan 30, 2002
Posts: > 500
From: down south
PM |
i enjoyed reading that rather long but interesting explanation. nice work. 
hehe, but as of now, GPRS in the Philippines is still free.... i hope it still stays long this way... 
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Posted: 2002-04-08 12:21
