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fadi mansor
New member
Username: Fadi1981

Post Number: 1
Registered: 07-2013
Posted on Monday, July 22, 2013 - 10:20 pm:   

Hi,
Kindly i get the below error when i try to send message
Retry Pending - ERROR: Timeout waiting for response from server or lost connection

note that i can ping the IP and make telnet on the port
Des - NowSMS Support
Board Administrator
Username: Desosms

Post Number: 4576
Registered: 08-2008
Posted on Tuesday, July 23, 2013 - 03:24 pm:   

Hi,

This happens with all messages you try to send over SMPP?

I assume that if you test the connection in the NowSMS configuration, it says the connection is ok?

In your SMPP configuration, is "Default Sender Address" blank?

That has been known to confuse some SMPP servers .... so my first suggestion would be to make sure a valid sender address is defined for "Default Sender Address".

Beyond that, did your SMPP provider give you any instructions about unusual parameters that might be required such as service_type and system_type?

--
Des
NowSMS Support
fadi mansor
New member
Username: Fadi1981

Post Number: 2
Registered: 07-2013
Posted on Wednesday, July 24, 2013 - 01:51 pm:   

Hi,

this problem happen for all the messages and for all the account , the connection start sending the messages then after one day or less than one day the system start give me this message.

I assume that if you test the connection in the NowSMS configuration, it says the connection is ok?
Yes, the connection give me OK


In your SMPP configuration, is "Default Sender Address" blank?
Yes ,because i have alot of senders

did your SMPP provider give you any instructions about unusual parameters that might be required such as service_type and system_type?
No, the did't give me any requirment

the provider told me that my application not return delivery_sm_resp

Note : when i restart my router the connection return UP
Des - NowSMS Support
Board Administrator
Username: Desosms

Post Number: 4580
Registered: 08-2008
Posted on Wednesday, July 24, 2013 - 03:28 pm:   

Hi,

So the connection works for awhile, then all messages fail.

The provider says the reason for the failure is that a delivery_sm_resp is missing.

Do I understand you correctly?

Questions and suggestions that come to mind ...

1. What is the version of NowSMS?

I am not aware of any past issues like this. We have seen similar problems where NowSMS is the SMPP server, and we did have one installation where we found a client would hang because we never received deliver_sm_resp. To resolve this issue, we updated the SMPP server in NowSMS to terminate the connection in the case of a missing deliver_sm_resp.

In your case, NowSMS is the SMPP client, so the above does not apply. I mention it only to emphasize that we do understand the type of problems that a missing deliver_sm_resp can cause.

2. Is async mode (window size) enabled for the SMPP connection in NowSMS?

It should not make a difference, but it might. If enabled, try disabling. If disabled, enable with a small window size like 5.

3. Are you bound as a single connection transceiver or as separate sender and receiver? (Separate sender and receiver is the default in NowSMS unless you enable transceiver mode in Advanced Settings.)

If your provider allows, separating the sender and receiver connections might resolve whatever is going wrong.

4. If the problem is really a missing deliver_sm_resp, I do have a theory.

NowSMS always sends a deliver_sm_resp, but in some instances, a single TCP/IP packet might contain both a submit_sm and a deliver_sm_resp, or possibly multiple deliver_sm_resp in the same TCP/IP packet.

That should not cause a problem, but I can see where maybe an SMPP server might not be prepared to handle this. We do have a configuration setting that disables this buffering and forces each SMPP request to be sent in its own TCP/IP packet. To enable this setting, edit SMSGW.INI and under the [SMSGW] header add SMPPNoDelay=Yes.

This setting was added in NowSMS 2009 and is available in all versions since then. I can't find any other threads where we have mentioned it ... as it was experimental and we never found a use for it as it slightly reduces performance under extreme loads. However, if the SMPP server is not seeing a deliver_sm_resp that NowSMS is sending, this is my best theory.

5. Another possibility is that the deliver_sm in question is somehow malformed and is not being recognized as such.

I would suggest enabling the SMSDEBUG.LOG. This will enable the SMPPDEBUG.LOG, which is the file we want to see. When the problem occurs, we want to see the SMPP activity on the connection that is occurring before the problem occurs. If you capture the problem in an SMPPDEBUG.LOG, please e-mail it to nowsms@nowsms.com with Attention: Des in the subject line.

--
Des
NowSMS Support
fadi mansor
New member
Username: Fadi1981

Post Number: 3
Registered: 07-2013
Posted on Monday, August 05, 2013 - 11:55 pm:   

Dear Hi,

Kindly i have sent you the log from 3 day ago did you receive it ?
Des - NowSMS Support
Board Administrator
Username: Desosms

Post Number: 4593
Registered: 08-2008
Posted on Tuesday, August 06, 2013 - 01:41 pm:   

Hi,

I did find your e-mail ... unfortunately as it did not contain "Attention: Des" in the subject header, it was not routed to me. So the person it was assigned to had no background information.

Looking at the log, what I see happening is that the provider seems to be terminating your connection.

My best guess is that they believe you have too many connections open, as it seems to be that each time you successfully connect, an earlier connection fails.

This is actually quite common behaviour. I should have guessed this when you mentioned a lost connection error.

By default, for each SMPP server connection defined, NowSMS creates two connections, a transmitter and a receiver. Under advanced settings, you can change this to a single connection transceiver (transmitter + receiver), and you can also adjust the number of connections.

From what I can see, you are using transceiver connections, and you have 3 separate connections using different bind/login accounts. When using different bind accounts, it is very odd for a provider to limit the number of connections across multiple accounts, so there may be something else happening (maybe they have a limit by IP address, which would be unusual).

I'd suggest trying with 2 connections, or even 1. See if that stabilizes connectivity. If it does, then I would be suspicious that the provider is limiting the number of connections.

I am still puzzled by the provider saying that they are not receiving a deliver_sm_resp. In those logs, before the connections fail, I see no evidence of deliver_sm or other unrecognized data packets. It may be worth enabling an async window if you have not already, and if possible going to a 2 connection sender/receiver instead of a transceiver. (Note: Normally we do recommend transceiver mode, but something is definitely not right here, and separating sender and receiver connections might make sense as that would separate submit_sm and deliver_sm activity.)

--
Des
NowSMS Support
fadi mansor
New member
Username: Fadi1981

Post Number: 4
Registered: 07-2013
Posted on Monday, August 12, 2013 - 04:19 pm:   

Kindly i have separate the connection to sending and receiving ,so the connection back allow me to send the messages but now i can't receive delivery report
Des - NowSMS Support
Board Administrator
Username: Desosms

Post Number: 4597
Registered: 08-2008
Posted on Tuesday, August 13, 2013 - 07:32 pm:   

I do not know what else to suggest, other than going back to my previous list of suggestions and trying others.

For example, you could reduce the number of SMPP binds but keep them as transceiver, as the provider seems to require that for delivery reports.

(It is up to the provider to route the delivery reports. Apparently this provider will only route them over a transceiver connection. There is nothing we can do to trigger them if the provider is not sending them.)

Did you try the INI file setting I mentioned?

Did you try changing the async settings to enable or disable async mode? What has it been set for during your troubles?

I also asked about the version of NowSMS in use???

Beyond all of this, the only thing I can suggest is setup Wireshark to trace all SMPP activity. Keep the trace running until the problem occurs. If there is really a missing deliver_sm_resp (which I do not think there will be), it would be shown in that trace, and we could determine why it is happening.

I don't mean to be difficult, I just don't have enough information to diagnose your problem.

--
Des
NowSMS Support

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