Thank you both for the attention and the feedbacks

Point clarified, it should be a new algorithms, something like :

   “13” - location optimized routing mode, the lowest latency gets higher priority (serial forking ordered by priority,  ds_ping_latency_stats is required).

The main drawback it that there is not load balancing, I would like to address this now, by making it configurable, an option to activate location optimized with load balancing routing mode.

I would like to find a clear and simple way to do this, that should be easy to document and understand.

For example in a scenario like that, it would be best that gateways with similar latency would get traffic load balanced to them, the priority could be overloaded to represent the threshold :




I found this simple formula : ADJUSTED_PRIORITY = PRIORITY - (ROUNDDOWN(ESTIMATED_LATENCY/PRIORITY))
Priority is also the threshold for latency priority adjustment, not sure if overloading it is creating confusion, in this example gateway 1, 4 and 6 would receive 33%/33%/33%, the other gateways would be only there for failover


GATEWAY PRIORITY ESTIMATED_LATENCY ADJUSTED_PRIORITY
1 30 21 30
2 30 91 27
3 30 61 28
4 30 19 30
5 30 32 29
6 30 0 30
7 30 201 24






















On Thu, May 28, 2020 at 9:08 AM Daniel-Constantin Mierla <miconda@gmail.com> wrote:

Hello,

maybe a dedicated module is going to be too complex or better said, duplicate a lot of code for management of the destinations, load/reload/keepalive, ... (although I won't have anything against such approach, if considered better by developer).

However, if done in dispatcher, I think that a new algorithm id should be used, leaving 8 as it is. Also, there should be a new field added in the internal structure to keep this "dynamic" priority -- it can be initialized to the "priority" value.

In some cases I use different algorithms for the same group of destinations, so it would be good to be able to use algorithm 8 with priority from database and the new algorithm at the same time.

Cheers,
Daniel

On 27.05.20 21:46, Henning Westerholt wrote:

Hi Julien,

 

sounds interesting, a “location optimized routing mode”. What about making it as a dedicated mode, to not overloading the mode “8”?

 

Cheers,

 

Henning

 

--

Henning Westerholt – https://skalatan.de/blog/

Kamailio services – https://gilawa.com

 

From: sr-dev <sr-dev-bounces@lists.kamailio.org> On Behalf Of Julien Chavanton
Sent: Thursday, May 14, 2020 7:26 PM
To: Kamailio (SER) - Development Mailing List <sr-dev@lists.kamailio.org>; Kamailio (SER) - Users Mailing List <sr-users@lists.kamailio.org>
Subject: [sr-dev] congestion control priority for priority based dispatching

 

Hi Folks,


Just found another simple use case of the dispatcher latency stats.

Just shraing this idea of a feature I want to contribute.


When using dispatcher algorithm 8:

   “8” - select destination sorted by priority attribute value (serial forking ordered by priority).

If the gateway as the attribute, the priority becomes the estimated latency.

   cc-priority

 

- The dispatcher would automatically prioritize the closest one.

- If a gateway is becoming unresponsive it will automatically become de prioritize.


Consider this real life scenario where you have gateways in East and West Coast

Example


URI: sip:28.71.19.140                                                                                                                                                                                      
FLAGS: AP
PRIORITY: 10
ATTRS: {
        BODY: cc_priority=1
}
LATENCY: {
        AVG: 84.001000
        STD: 0.062000
        EST: 84.001000 (high == low priority)
        MAX: 93
        TIMEOUT: 0
URI: sip:28.71.16.140
FLAGS: AP
PRIORITY: 10

ATTRS: {
        BODY: cc_priority=1
}

LATENCY: {
        AVG: 29.110000
        STD: 2.383000
        EST: 31.999000 (low == high priority)
        MAX: 1499
        TIMEOUT: 1

 

 

Another major improvement to all of this would be to gather stats on INVITE <> 100 to have a very accurate latency estimation even if the gateway does not support SIP OPTIONS pings

 

 


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Daniel-Constantin Mierla -- www.asipto.com
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Funding: https://www.paypal.me/dcmierla
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