2nd MMS always fails with PT-2

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Matt Allie
New member
Username: Matt

Post Number: 13
Registered: 02-2004
Posted on Wednesday, March 17, 2004 - 09:56 pm:   

Hello,

I created the same thread under the WAP discussion board: i put it here since it seems that this one gets more attention...sorry about that!
Logs are attached to the one under WAP board.



I'm using Nokia PT-2 phones (Observation Camera)to send VGA snapshots via MMS at regular intervals.

The first MMS is always successful, but the 2nd one seems to hang towards the end of the UL transfer.
It works this way: PT-2 takes a snaphots, then GPRS attaches, then activates a PDP and then sends the MMS containing one jpeg attachment.

I dont know why the 2d one fails: it hangs and stay there forever until I reset the phone.
The MMS size is around 50kbytes.

I'm using nowSMS WAP gateway and MMSC.
SGSN is 10.176.99.100
PT-2 gets IP@ 10.176.98.0 (GSN has NAT enabled).
WAP and MMSC run on same WinXP laptop: 10.176.99.40.
PT-2 sends MMS using a VASP account: received MMS is stored in MMS-IN directory. No MMS limit is set for the VASP account!

Attached are the WAP debug files: it contains 2 MMS: the first one is successful and the second failed. Looks like the WAP session is still hanging...it the WAP expecting more data?

Thanks for your help!

-Matthieu
Bryce Norwood - NowSMS Support
Board Administrator
Username: Bryce

Post Number: 2149
Registered: 10-2002
Posted on Thursday, March 18, 2004 - 02:18 am:   

Matt,

I studied your log over in the WAP Proxy section, and I was able to come up with a scenario that recreated your problem.

I did notice that if I wait about 5 minutes after the first attempt, then the second attempt is fine.

So that has me puzzled, but my colleague Kent promised me he'd look into this first thing in the morning ... especially as I gave him a 100% recreatable scenario thanks to some info I was able to get from your logs.

-bn
Matt Allie
New member
Username: Matt

Post Number: 16
Registered: 02-2004
Posted on Thursday, March 18, 2004 - 04:12 am:   

thanks for ur prompt reply.
what is weird is that with other MS (with the Sony P800 for instance), i can send as many MMS as i want w/o waiting in- between each MMS...
anyway, i'll wait to see if u get more feedback.
thanks again
Bryce Norwood - NowSMS Support
Board Administrator
Username: Bryce

Post Number: 2155
Registered: 10-2002
Posted on Thursday, March 18, 2004 - 03:17 pm:   

Yes, recreating this was quite a challenge.

I found a phone that I could recreate it with, but I had to turn the phone off between requests in order to trigger the problem.

Kent's testing a fix, so it shouldn't be too much longer.
Matt Allie
New member
Username: Matt

Post Number: 17
Registered: 02-2004
Posted on Thursday, March 18, 2004 - 04:04 pm:   

Loking at the SGSN logs, this is what i can see:

When Mobile invoke second MMS second, WAP
does not respond back with Delivery Report, due to which Mobile was not able to clear Web Session.
Because in Second case both the Originator and Destinationis same one as in first MMS, it may be that Identification of MMS message may be same in both the cases, due to which SERVER may not responding back with Delivery Report. Since
Mobile is waiting for Delivery report, it does not
close the Web Session.
Restart the WAP makes the 2d MMS successful which seem to confirm the above theory...

thanks!
Kent Williams
Moderator
Username: Kent

Post Number: 44
Registered: 10-2003
Posted on Thursday, March 18, 2004 - 04:44 pm:   

Hi Matt,

This is a tough one to explain. But the problem does have to do with the facts that:

1.) The device gets assigned the same IP address on each connection, and connects from the same port on each connection.

2.) The device starts its transaction id counter at 1 for each connection, so the MMS transaction has the same id each time.

We maintain some state information about SAR transactions, even after they have been completed, so that the gateway can respond intelligently to lost packets that arrive out of sequence.

But that state information should be cleared by a connect/disconnect and it is not.

As Bryce mentions above, it is automatically cleared after 5 minutes ... and there is a config setting to adjust this, but I don't think it is worth going into. The better solution is to fix the problem so that the state information is properly cleared.

I've uploaded an update to http://www.nowwap.com/download/update.zip. Stop the Now.WAP service. Use the file in the ZIP to update the existing file of the same name. Then restart the service, and this should take care of the problem.

--
Kent Williams
Now Wireless Support
Matt Allie
New member
Username: Matt

Post Number: 18
Registered: 02-2004
Posted on Thursday, March 18, 2004 - 09:34 pm:   

I tried the patch and it is working fine!

thanks a lot for your prompt support!
I'm spreading the word about nowsms...;-)

-Matt

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