[SR-Users] Kamailio propagates 180 and 200 OK OUT OF ORDER

Fri Apr 10 03:19:11 CEST 2020

An ACM in a 180?

On Thu, 9 Apr 2020 at 21:37, Luis Rojas G. <luis.rojas at sixbell.com> wrote:

> Hello, Daniel,
>
> Yes, yes, yes, you are right. I got confused for a moment. Yes, the
> criteria for dispatcher is only for the request.  And so, it will have no
> effect on the replies.  On the replies only the via headers are considered.
> Wel, moving to round robin increased the throughput for a single instance.
> Now it can process over 1000 CAPS.
>
> For the scenario ack-reinvite, the solution adding a small delay for
> re-invite, using something like async_ms_sleep() will solve it, so I am not
> worried ( I mentioned on a previous post that I have seen also that
> scenario happening with this operator. Re-invite immediately after ACK, and
> it caused us problems)
>
> My problem is still 180-200.  it will not matter the number of processes
> or cores. In the end, it's a classical multi-process/multi-threaded race
> condition. Considering the architecture of Kamailio, with multiple
> processes, the problem will appear. And the more the traffic, the more
> close in time 180 and 200 are, the more it will happen. With my currents
> test, with 180 and 200 very close,  I am getting around 0.5% of cases
> suffering from that condition.
>
> I know, if you think in "only SIP", yes, it's not so important the 180.
> it's important in my case, because my customer is very complicated, and
> they will not like to see messages coming to our platform in one order and
> going out in other.
> And the second : it's not only SIP.  they usually have interworking, and
> 180 then will carry an ISUP ACM body that is important. As I mentioned in a
> previous post, for instance, the Backward Call Indicators, with very
> important subfields like the Charge Indicator.
>
> I understand. It's UDP. Messages can be lost on the network. OK. Messages
> can arrive out of order. OK.  But i't s pity that if messages were not lost
> and arrived in order, they leave kamailio out of order.
>
> So far the only solution I see is to try to insert a small delay before
> forwarding the 200.
>
> Best rgards,
>
> Luis
>
>
>
> On 4/9/20 3:58 PM, Daniel-Constantin Mierla wrote:
>
>
> MICONDA at GMAIL.COM appears similar to someone who previously sent you
> email, but may not be that person. Learn why this could be a risk
> <http://aka.ms/LearnAboutSenderIdentification>
> Feedback <http://aka.ms/SafetyTipsFeedback>
>
> Hello,
>
> dispatcher has nothing to do with handling sip replies. It is intended
> only for routing sip requests. If you use dispatcher for replies, you do it
> wrong, just let kamailio route them based on Via headers.
>
> So maybe I was looking at the wrong message flow processing, I was
> speaking mainly about the case when the caller sends quickly the reINVITE
> after the ACK to the initial INVITE 200ok and the reINVITE gets to callee
> before the ACK. That was more of a branching in discussion on Alex' remarks
> and the situation that I enocountered in the past and created troubles.
> Never had to deal with troubles caused by change of order between 180 and
> 200. In IP world, if the time between 180 and 200 is very short, it doesn't
> matter at all, because the 180 is for start play a ring tone, which a human
> may not even hear it when 200 comes 50ms after it.
>
> If you face the re-ordering for replies, then Kamailio doesn't do much
> internally if you don't have reply_route{} (as well as no onsend_route) in
> config file, provided that you do not use tm module for sending out (and by
> that no onreply_route or failure_route).
>
> For a sip reply, kamilio is parsing the headers to find the 2nd Via header
> and use that address to send out the reply. The request route is not
> executed for sip replies.
>
> What you can try is to set number of kamailio processes not to exceed the
> number of CPU cores, so there is "no real competition" to get CPU cycles.
> It could improve a bit, but still not a 100% accuracy (ie., there are other
> processes running on the system).
>
> Cheers,
> Daniel
> On 09.04.20 21:29, Luis Rojas G. wrote:
>
> Hello,
>
> I just realized that I had the dispatcher configured using a hash of
> Call-ID.  That means, after recvfrom there must be an extra processing
> finding the Call-ID header in message, to calculate a hash and then
> forward() message. The more the processing, the more cases when 200 could
> arrive  before 180. I just changed it to round robin, and the amount
> decreased a lot, but it's still there. If I send a burst of 1000 messages,
> about 5 of them leave out of order every time.
>
> Best regards,
>
> Luis
>
>
>
> On 4/9/20 1:48 PM, Luis Rojas G. wrote:
>
> Hello,
>
> I have a lot of experience developing mutithreaded applications, and I
> don't see it so unlikely at all that a process loses cpu just after
> recvfrom(). It's just as probable as to lose it just before, or when
> writing on a cache or just before of after sendto(). If there are many
> messages going through, some of them will fall in this scenario. if I try
> sending a burst of 100 messages, I see two or three presenting the scenario.
>
> Just forward() with a single process does not give the capacity. I'm
> getting almost 1000caps. More than that and start getting errores,
> retransmissions, etc. And this is just one way. I need to receive the call
> to go back to the network (our application is a B2BUA), so I will be down
> to 500caps, with a simple scenario, with no reliable responses, reinvites,
> updates, etc. I will end up having as many standalone kamailio processes as
> the current servers I do have now.
>
> I really think the simplest way would be to add a small delay to 200 OK.
> Very small, like 10ms, should be enough. Simple and it should work. As Alex
> Balashov commented he did for the case with ACK-Re-Invite.
>
> I have to figure out how to make async_ms_sleep() work in reply_route().
>
> Thanks for all the comments and ideas
>
> Best regards,
>
> Luis
>
>
>
> . On 4/9/20 12:17 PM, Daniel-Constantin Mierla wrote:
>
>
> MICONDA at GMAIL.COM appears similar to someone who previously sent you
> email, but may not be that person. Learn why this could be a risk
> <http://aka.ms/LearnAboutSenderIdentification>
> Feedback <http://aka.ms/SafetyTipsFeedback>
>
> Hello,
>
> then the overtaking is in between reading from the socket and getting to
> parsing the call-id value -- the cpu is lost by first reader after
> recvfrom() and the second process get enough cpu time to go ahead further.
> I haven't encountered this case, but as I said previously, it is very
> unlikely, but still possible. I added the route_locks_size because in the
> past I had cases when processing of some messages took longer executing
> config (e.g., due to authentication, accounting, ..) and I needed to be
> sure they are processed in the order they enter config execution.
>
> Then the option is to see if a single process with stateless sending out
> (using forward()) gives the capacity, if you don't do any other complex
> processing. Or if you do more complex processing, use a dispatcher process
> with forwarding to local host or in a similar manner try to use
> mqueue+rtimer for dispatching using shared memory queues.
>
> Of course, it is open source and there is also the C coding way, to add a
> synchronizing mechanism to protect against parallel execution of the code
> from recvfrom() till call-id lock is acquired.
>
> Cheers,
> Daniel
>
>
> --
> Luis Rojas
> Software Architect
> SixbellLos Leones 1200
> Providencia
> Santiago, Chile <https://www.google.com/maps/search/Los+Leones+1200%0AProvidencia%0ASantiago,+Chile?entry=gmail&source=g>
> Phone: (+56-2) 22001288mailto:luis.rojas at sixbell.com <luis.rojas at sixbell.com>http://www.sixbell.com <https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.sixbell.com%2F&data=02%7C01%7C%7Cdc7f541ef3c74e85e61008d7dcc0562d%7Cab4a33c2b5614f798601bc921698ad08%7C0%7C0%7C637220590981766356&sdata=D2B0niyYm9fstMXOG9b%2BMzlbc3pZmt72mkL3PPPy7kY%3D&reserved=0>
>
> --
> Daniel-Constantin Mierla -- www.asipto.com <https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.asipto.com%2F&data=02%7C01%7C%7Cdc7f541ef3c74e85e61008d7dcc0562d%7Cab4a33c2b5614f798601bc921698ad08%7C0%7C0%7C637220590981766356&sdata=DO4yFB3gccT5ZXuv37oOLIri%2BF5jTnA4kHQaIjV0YbQ%3D&reserved=0>www.twitter.com/miconda <https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.twitter.com%2Fmiconda&data=02%7C01%7C%7Cdc7f541ef3c74e85e61008d7dcc0562d%7Cab4a33c2b5614f798601bc921698ad08%7C0%7C0%7C637220590981776349&sdata=x%2BMcm9Dv%2FGY4fg54k6EbQIwHyeAMe4Y6hZrNCfOG4Q4%3D&reserved=0> -- www.linkedin.com/in/miconda <https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.linkedin.com%2Fin%2Fmiconda&data=02%7C01%7C%7Cdc7f541ef3c74e85e61008d7dcc0562d%7Cab4a33c2b5614f798601bc921698ad08%7C0%7C0%7C637220590981786347&sdata=b86Wa3h84oy0BcVl6pLOqLwgi4Fssya2re7Y1GOiEd4%3D&reserved=0>
>
>
> --
> Luis Rojas
> Software Architect
> SixbellLos Leones 1200
> Providencia
> Santiago, Chile <https://www.google.com/maps/search/Los+Leones+1200%0AProvidencia%0ASantiago,+Chile?entry=gmail&source=g>
> Phone: (+56-2) 22001288mailto:luis.rojas at sixbell.com <luis.rojas at sixbell.com>http://www.sixbell.com
>
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-- 
Regards,

David Villasmil
email: david.villasmil.work at gmail.com
phone: +34669448337
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