SOS: submit_sm slow - TCP checksum incorrect

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Levi
New member
Username: Levi

Post Number: 6
Registered: 12-2003
Posted on Friday, November 10, 2006 - 06:05 am:   

Hi All,
I got this strange prob: my NowSMS SENDING performance just slowed down dramatically (1-2 sms/sec). I'm using NowSMS 5.51k and connect by SMPP. Using Ethereal to capture it looks like ALL the submit_sm packet has checksum incorrect meanwhile the Delivery_sm is OK (I still can receive requests at normal speed).
Please advice ASAP!
Many thanks in advance!
BR Levi
Bryce Norwood - NowSMS Support
Board Administrator
Username: Bryce

Post Number: 6817
Registered: 10-2002
Posted on Friday, November 10, 2006 - 03:52 pm:   

Hi Levi,


quote:

Using Ethereal to capture it looks like ALL the submit_sm packet has checksum incorrect.




I've seen this in a lot of Ethereal captures. Enough that it doesn't concern me. I've always assumed that it had something to do with NAT routers and address translation.

In any event, NowSMS doesn't generate any of these checksums, they are all generated by the TCP/IP stack on the machine.

All I can say is that I've seen this enough that I wouldn't be concerned by it.

For maximum speed, you should make sure that the "Async mode" is configured for the SMPP connection, and you need to declare a window size.

There is no recommendation for the window size, as it requires experimentation and really depends on the SMSC that you are connecting to. If you set the window size too high, you might end up with submission errors.

Basically, without async mode, NowSMS waits for an acknowledgement from the SMSC before submitting the next message. With async mode, NowSMS will allow up to the window size number of messages to be sent to the SMSC while waiting for the SMSC to acknowledge receipt. You generally need to use async mode to get better than 3 to 5 messages per second (but sometimes you need it at lower speeds, depending on latency of the connection to your SMSC and performance quirks of that SMSC).

Another issue is that if all of your messages are being submitted with delivery receipt requested, this will drastically slow down message submission. Improvements in this area have been made with the latest update for NowSMS 2006, with further enhancements planned in another update in the next several months.

-bn
Levi
New member
Username: Levi

Post Number: 7
Registered: 12-2003
Posted on Tuesday, November 14, 2006 - 11:55 am:   

You are the man Bryce!
I've been trying to play with SMPPThrottleErrorDelay, CommandTimeOut and Retry params with no luck! But this WindowSize just solved my prob.
Really appreciate your help!
Levi