Data splitting while transmission


#1

I have the problem with Q24 plus,that a small packet of 100 bytes is split into 2 packets and sent over GPRS.My application at the server interprets this as 2 different datas and processes the same which is creating a big problem.

Please someone solve the issue…
Thanks in advance.


#2

Surely, it is in the nature of TCP/IP that data could get split between packets, so your server should be able to cope with this?


#3

Hi awneil,

You are right I dont have any other option then to take care at the comm. server.
Thanks.

Regards
SM Ahmed


#4

Of course it shouldn’t cause any trouble for a comm. server, but if the 100 byte really split into two packet than it suggest erratic behaviour. It could mean much more effective traffic on your gprs bill. Are you sure that the packet is split? Did you do a TCP dump on the module? Or you just experience it at the server side? Did you temper with the WIP parameters?

tom


#5

Wipsoft tends to cut the first packet a bit short, I don’t know why. I guess it has something to do with DLE+ETX escaping. This doesn’t happen with Wiplib (i.e. C programs loaded on the WCPU). It also doesn’t happen on long stretches of data, so don’t bother too much about communication costs.


#6

hi smahmed and all,

I would say you are all right and that TCP/IP is allowed to split packets as much as they want … and that server should be able to cope with it!! I have experienced this also and though it can be seen as an eratic behavior I was explained it is not… It seems to be by design in WIPsoft…

The problem when splitting packets is that you pay for extar data over GPRS so it is not very good for our solutions… so I kept this in mind and guess what? the last delivery fo WIPSoft (v3.01) allows us to choose between let the stack split the packets as it like or ask him to not split packets and wait as much as possible before sending data to avoid this…

Guess what I chosed!!!


#7

Hi,

Tomalex said:

I have some problems on my GPRS connection using HTTP librairy, and i’m interested in this procedure for TCP dump on the module ! Tomalex, could you explain how can i do a TCP dump ? or if somebody is able to explain how doing a TCP dump ?

Thank you in advance.

Regards


#8

you should take a look into chapter ‘TCPIP debug tool’ of the manual ‘TM_Tools_Manual_for_Open_AT.pdf’ shipped by the Open AT SDK. If you replace the command ‘At+ADLDBG=50’ by ‘At+ADLDBG=60’ it even works …

Regards, Ralf


#9

AT+ADLDBG=60 command is used to get IP packets. The packets are received in TMT (CUS4[25]).
Then you can save the txt file with the traces and convert it to wm_trc2tcpdump.awk cygwin command to the TCPDUMP format.
The TCPDUMP file can be read with a special software like ethereal

I hope it helps


#10

Thank you for your explanation.
I will test that as soon as possible. Just another question : where do i typed the command wm_trc2tcpdump.awk ? i never use cygwin. i work on windows platform. So, where can i find cygwin ? in wavecom directory ? on CD ?

Regards


#11

Oh yes you do - the entire Wavecom build system depends upon Cygwin!

It is installed as part of the Wavecom installation.


#12

Is this facility still available :question:

If so, does Developer Studio support it, it does it still have to be done via TMT :question:

BTW: “ethereal” is now Wireshark: wireshark.org/