[SR-Users] The Algorithm “13” - latency optimized dispatching

[Julien Chavanton]

About your fiber optics failing, if they get congested unresponsive and
then fails like it is the case most of the time on the Internet due to
buffers etc. It should help.

The estimator will do a better job at remembering if one is more stable
than the other.


On Sat, Nov 14, 2020, 08:27 Julien Chavanton <jchavanton at gmail.com> wrote:

> Sounds good,
>
> https://github.com/kamailio/kamailio/pull/2493
>
> At this point l, I am simply waiting to see if we get another review, more
> testing is always a plus and if something is not clear in the doc etc. And
> get the approval.
>
> I am interested about your use case and settings, this will be a good
> exercise to make sure using this algorithm is clear and simple.
>
> The priority is also the threshold in ms at which a gateway should be
> de-prioritised for example in the US East and West coast 30ms could be a
> good choice.
> To make sure that under normal conditions the you are using a gateway that
> is closer.
>
> Under problematic conditions,
>  you may want the estimator to react and adjust quickly, you can tune the
> estimator. This is not crucial but you can decide if it should have more
> long term memory or not using the latency alpha.
>
> I think I should write a little blog article about it, would be best if it
> was a wiki because my first drafts are usually terrible and I like to come
> back and improve it.
>
> Looking forward your feedback
>
> On Sat, Nov 14, 2020, 08:03 Joel Serrano <joel at textplus.com> wrote:
>
>> First of all, s/Juha/Julien/g on my previous email (Sorry!)
>>
>> That said, what branch are you working on? I’m happy to test it.
>>
>> I have a setup in Panama (multiple kams, working as a cluster in
>> different physical locations), the 2 sites are interconnected with direct
>> fiber connection that fails very often (Panama Internet quality is not the
>> best). We also have asterisk boxes in each location. All kams can reach all
>> asterisks. Every now and then, the interconnectivity degrades (but doesn’t
>> fail) although calls are affected (latency) what we normally do in these
>> cases is force-route to only a specific set of servers from one location
>> until the degradation is over.
>>
>> I almost sure this version of algorithm 13 will handle that case totally
>> automatic for us.
>>
>> Really excited about this!
>>
>> Joel.
>>
>>
>> On Fri, Nov 13, 2020 at 18:10 Julien Chavanton <jchavanton at gmail.com>
>> wrote:
>>
>>> I did some load tests today and added a comment on the pull request.
>>>
>>> My status is that this is production ready.
>>> But it is not yet merged in master, if you want to use it you will have
>>> to use master or cherry-pick a few commits because there was some
>>> refactoring done to facilitate the integration and the review.
>>>
>>> Happy Friday the 13th.
>>>
>>> On Fri, Nov 13, 2020, 14:54 Joel Serrano <joel at textplus.com> wrote:
>>>
>>>> Thanks Juha!! I have a perfect use case for this algorithm.
>>>>
>>>> Is it tryable ?
>>>>
>>>> Joel.
>>>>
>>>> On Fri, Nov 13, 2020 at 5:57 AM David Villasmil <
>>>> david.villasmil.work at gmail.com> wrote:
>>>>
>>>>> Nice!
>>>>>
>>>>> On Thu, 12 Nov 2020 at 22:01, Julien Chavanton <jchavanton at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> About The Algorithm “13” - latency optimized dispatching,
>>>>>>
>>>>>> Is now reviewed once and tested, it will most likely be ready to
>>>>>> merge soon.
>>>>>>
>>>>>> I want to share my thoughts on it one more time as it is not too late
>>>>>> to get more feedback before we merge.
>>>>>>
>>>>>> I think it is the best algorithm in most use cases, here is why :
>>>>>>
>>>>>> It is providing round-robin and fail-over with automatic
>>>>>> de-prioritization of slow/unresponsive gateways.
>>>>>>
>>>>>> You probably asked yourself the following questions in the past :
>>>>>> "How do I set the thresholds to put a gateway out of service ?"
>>>>>>
>>>>>> *ds_probing_threshold*, *ds_inactive_threshold* and timers ...
>>>>>>
>>>>>> - If your thresholds are too strict, you may end up running out of
>>>>>> gateway.
>>>>>> - If your thresholds are too tolerant, you may end up adding
>>>>>> excessive delays to call establishment and using degraded gateways.
>>>>>>
>>>>>> The automatic de-prioritization can help to address this concern more
>>>>>> efficiently by providing more flexibility.
>>>>>>
>>>>>> - it can react faster than lets say 2 consecutive timeouts.
>>>>>> - it will not disable gateways but simply de-prioritize / reorder
>>>>>> them if needed.
>>>>>>
>>>>>> The only main drawback I can imagine is when you always need to
>>>>>> evenly distribute calls using round-robin.
>>>>>> It may be needed sometimes but in this case it means you are willing
>>>>>> accept to send calls to a degraded gateway or trough degraded network paths.
>>>>>>
>>>>>> Even if you may select to preset a mixture of round-robin sets,
>>>>>> thanks to *ds_select_routes* however it will stay static, needs to
>>>>>> be configured precisely, and will not react to degradation automatically.
>>>>>>
>>>>>> I hope this will help use to protect QoS and lower latency of calls
>>>>>> routed by Kamailio.
>>>>>>
>>>>>> Feel free to let me know what you think
>>>>>> Julien
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Kamailio (SER) - Users Mailing List
>>>>>> sr-users at lists.kamailio.org
>>>>>> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>>>>>>
>>>>> --
>>>>> Regards,
>>>>>
>>>>> David Villasmil
>>>>> email: david.villasmil.work at gmail.com
>>>>> phone: +34669448337
>>>>> _______________________________________________
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>>>>>
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