Hello,

besides Alex' suggestion to look at AWS PPS limits, few things to take in consideration in such case:

  - if CPU usage is low, then if you use DNS for routing, be sure that DNS server is very responsive
  - if you do auth with database, be sure that database is very responsive
  - if you print extensive log messages, be sure syslog is configured asynchronous
  - check the received queue on sip port with netstat, if it is high value, then kamailio is stuck in some operations (like those above) and doesn't read as fast as the end point transmits
  - if sipp runs on a low capacity system, I noticed that it cannot handle the responses at high throughput even when they are sent to it and it actually thinks it hasn't received them and do retransmissions

Cheers,
Daniel

Hi Guys,

I am running a simple REGISTER load test on:

1) Kamailio sever with 2 cores - mem 5G

2) Kamailio server with 4 cores - mem 16G

Both are EC2 instances.

At -r = 500 i.e. 500 reg/sec sipP test works fine with very few re-trans. But when i increase it to 800 reg/sec it starts retransmissions in bulk. 

I don't see server's CPU, load-avg or memory shooting. Running everything by default, even using kamctl to start the instance. So I have not tuned any params yet. 

My main concern is how can I make server choke and get its actual capacity, and avoid these retransmissions as apparently kamailio is not even utilizing 2 cores and CPU usage is under 10 always.

Results of both server is same i.e. 500 reg/sec max so I am sure there is some problem that needs a fix, but need some hints here.

Also used multiple SIPp's to rule out if it is SIPp issue, but after 500 I see same problem.

Regards,

JSZ

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