Maybe the documentation should be improved, it seems the first bullet point should say.

"The algorithm will load balance using round-robin prioritizing the gateways with the highest adjusted priority. "

On Thu, Sep 1, 2022 at 9:06 AM Julien Chavanton <jchavanton@gmail.com> wrote:

Hi, did you look at the documentation of  algorithm 13 ?

The priority is used in combination with the latency to determine the preferred gateway.

Once you confirm that this is what you want "latency latency optimized dispatching", we can help to clarify why and how this may not work as expected.

Regards

https://kamailio.org/docs/modules/devel/modules/dispatcher.html

• “13” - latency optimized dispatching

  - The algorithm will load balance using round-robin prioritizing the gateways with the highest priority.

  - If ds_ping_latency_stats is active the algorithm will adjust the priority of the gateway automatically, the priority will be lowered by 1 point every time the latency ms is as high as the priority.

  - If the attribute 'cc=1' is set, the latency used is congestion ms : estimate (current latency ms) - average (normal condition latency ms).

  Example 1.46. latency_optimized_dispatching usage

  Using this simple formula :
      ADJUSTED_PRIORITY = PRIORITY - (ESTIMATED_LATENCY_MS/PRIORITY)
  
  GATEWAY | PRIORITY | ESTIMATED | ADJUSTED | LOAD
     #    |          |  LATENCY  | PRIORITY | DISTRIBUTION
     1    |    30    |    21     |    30    | 33%
     2    |    30    |    91     |    27    | 0%
     3    |    30    |    61     |    28    | 0%
     4    |    30    |    19     |    30    | 33%
     5    |    30    |    32     |    29    | 0%
     6    |    30    |    0      |    30    | 33%
     7    |    30    |    201    |    24    | 0%
  
  
  With congestion control the formula becomes :
      CONGESTION_MS = CURRENT_LATENCY_MS - NORMAL_CONDITION_LATENCY_MS
      ADJUSTED_PRIORITY = PRIORITY - (CONGESTION_MS/PRIORITY)

  
  

• 
  

On Thu, Sep 1, 2022 at 2:38 AM Pyry Aaltonen <pyry.aaltonen@cuuma.com> wrote:

Hello,

 

I’m quite new user with kamailio (heard first time about it a year ago and joined the list yesterday) and now wondering how the xavp_dst should work.

 

I had read from the documentation that

”The first XAVP is the current selected destination.”

 

I use ds_select_dst with alg 13. And my kamailio version is kamailio 5.5.3 (x86_64/linux)

 

So when my dispatcher list is like (I have also tried to differ the priority value like 10 and 1, but doesn’t make difference)

10 sip:1.2.3.4;transport=tcp 10 1 type=type1

10 sip:4.3.2.1;transport=tcp 10 1 type=type2

 

If one of the destinations fails (dx/ip), and it happens to be the one with higher priority or the one that just gets higher position in the dispatcher list if the prio Is equal.

My xavp_$xavp(dsdst=>attrs) get null value. And, if I try to seek $(xavp(dsdst[0]=>attrs) or $(xavp(dsdst[1]=>attrs) I also got nothing.

 

If both destinations are up with equal priority, it selects them with round-robin, and the xavp_$xavp(dsdst=>attrs) has the type value of the selected destination as expected, also the $(xavp(dsdst[0]=>attrs) or $(xavp(dsdst[1]=>attrs) contains the destinations so that the selected is 0 and the other is at position 1.

The $du is updated as I expect so if one fails the other one is selected always, why the xavp_dst isn’t working same way, or am I missing something?

 

If needed I’ll try to provide more information,

Thanks already in advance

 

-Pyry

 

 

 

 

 

 

 

 

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