[SR-Users] Dispatcher module and xavp_dst

Mon Sep 5 15:02:11 CEST 2022

Seems like you are on the right track, FYI I will have a look by the end of
the day tomorrow.

On Mon, Sep 5, 2022, 6:06 AM Pyry Aaltonen <pyry.aaltonen at cuuma.com> wrote:

> Hi,
>
>
>
> I´ve looked now closer the commit and overall the dispatch.c, and I think
> the problem is related to that problem which was fixed in that commit which
> I linked previously.
>
> (I looked the code from master in github)
>
> As a background I need to mention that its been over 10years since I´ve
> last read this much c-code so might be that I’m wrong 😊
>
>
>
> But..
>
>
>
> I cant quite tell you what the problem exactly is but to me it looks like
> there is something with the
>
> ds_sorted list and its reordering, combined with the function call of the
> ds_add_xavp_record with ds_sorted[i].idx, in the function
> ds_manage_routes_fill_reodered_xavp.
>
> (btw it probably should be reoRdered instead of reodered)
>
>
>
> I think the loop there messes up the referencing order of destinations in
> a situation where the highest priority destination is inactive.
>
>
>
> And it seems like It is happening only when the original order of the set
> is changing (which was fixed in the commit I linked previously)
>
> Because when for example set with 2 destination
>
>
>
> Dest1 prio 10
>
> Dest2 prio 0
>
>
>
> Both active -> xavp -> has values
>
> Dest2 inactive -> xavp -> has values
>
> Dest1 inactive -> xavp -> null
>
>
>
> So I guess somehow the same thing should need a fix in the
> ds_add_xavp_record or probably in the call for that in the
> ds_amange_routes_fille_reodered_xavp function.
>
>
>
>
>
> Does this make any sense to anyone else?
>
>
>
>
>
> -Pyry
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> *From: *sr-users <sr-users-bounces at lists.kamailio.org> on behalf of Pyry
> Aaltonen <pyry.aaltonen at cuuma.com>
> *Date: *Friday, 2. September 2022 at 7.56
> *To: *Kamailio (SER) - Users Mailing List <sr-users at lists.kamailio.org>
> *Subject: *Re: [SR-Users] Dispatcher module and xavp_dst
>
> Hi,
>
>
>
> Thank you for your responses!
>
>
>
> I don’t have latency stats enabled, but I do want to have load balance
> using round-robin by priorities, and that’s why I’m using algo13 instead
> algo 8, cause algo 8 doesn’t round-robin if the priorities are the same,
> and still, I do want to have priorities and not only round-robin and that’s
> why I’m not using algo4 either.
>
> So algo13 should be fine and the dispatching works just like it is
> described in the documentation, only the xavp_dst values aren’t updated
> like it should (I think 😊)
>
>
>
> Yesterday when I was searching around this issue of mine, I found out this
> quite recent commit
> https://github.com/kamailio/kamailio/commit/adba3caa2d12d1f8b89d720fbb9a6a9cdc8b2573
>
> The description of that commit looks quite same that what I’m now facing
> with only the xavp_dst values.
>
> If the highest priority destination is inactive the destination is updated
> but the corresponding xavp_dst values are not correct(or missing
> completely).
>
>
>
> With my previous destination examples
>
> If first trunk is inactive, the destination is set correctly to second
> one, but the xavp_dst values are null, and I think xavp_dst values should
> be “type=2” or something like that.
>
> 10 sip:1.2.3.4;transport=tcp 10 1 type=type1
>
> 10 sip:4.3.2.1;transport=tcp 10 1 type=type2
>
>
>
> -Pyry
>
>
>
>
>
>
>
> *From: *sr-users <sr-users-bounces at lists.kamailio.org> on behalf of
> Julien Chavanton <jchavanton at gmail.com>
> *Date: *Thursday, 1. September 2022 at 16.33
> *To: *Kamailio (SER) - Users Mailing List <sr-users at lists.kamailio.org>
> *Subject: *Re: [SR-Users] Dispatcher module and xavp_dst
>
> The rest of the dispatcher "features", like failover should be supported
> based on what I remember from the way it was integrated and tested.
>
> If it is not the case I can have a look.
>
>
>
>
> On Thu, Sep 1, 2022 at 9:21 AM Julien Chavanton <jchavanton at gmail.com>
> wrote:
>
> On second thought, the documentation looks accurate to me.
>
> Do you have the latency stats enabled ?
> 3.26. ds_ping_latency_stats (int)
>
>
>
> If yes, the priority values you are using seem a bit low 1ms and 10ms.
>
> If not, the algorithm should behave simply like that :
>
> "The algorithm will load balance using round-robin prioritizing the
> gateways with the highest priority. "
>
>
>
>
>
>
>
>
> On Thu, Sep 1, 2022 at 9:09 AM Julien Chavanton <jchavanton at gmail.com>
> wrote:
>
> 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 at 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 at 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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