hi Benjamín,

>Can the registrars behind the proxy listen only to the internal network address or do they need a public IP as well?
  yes - at the edge proxy you need to listen on a separate interface and use force_send_socket() when shifting interfaces from public/private or from private/public (my prefered method). Another options is to use `mhomed=1` and let kamailio automatically "shift interfaces", I have found this is more overhead for kamailio and manually using force_send_socket() scales better.

>If the registrars are in an internal network along with the edge proxy, shouldn't the proxy add the internal address as the Path instead of the public?  
  yes but you might need to enable the received param for this to work too.
  I actually found using contact_alias'ing works really well for this setup. Some Kamailio users may not agree with me on using `contact_alias` since `path` is specifically designed for this use-case.

>I am seeing that despite the header Path being added, the registrar is trying to relay the INVITE messages to the UAC and not to the proxy, I am using several parameters of the registrar module in the registrar servers such as: use_path(1), path_mode(0), path_use_received(1), path_chek_local(1).
  you may need to use `add_path_received()`
  also `contact_alias` might work (i like this method but others may not agree with me)

>Do I have to still tweak the request manually (that is messing with $du/$ru) in order for the packet to go back to the proxy?
  No, given you are setting up path correctly on edge & registrar, you should not need to modify pseudovars.

Feel free to email me directly if you need assistance on this, I've set it up many times and in many different environments.
Hope this helps.

On Fri, Sep 11, 2020 at 11:59 AM Benjamín Visón <bvisonl@gmail.com> wrote:
Thank you Emmanuel,

I am testing out your suggestion but I am encountering an issue and I would like a little guidance if possible. I've setup an edge proxy doing just a load balance with the dispatcher module. Behind that proxy there is another kamailio which  is acting as a registrar. I've confirmed that the proxy is adding the path header. 

I have a couple of questions:

- Can the registrars behind the proxy listen only to the internal network address or do they need a public IP as well?
- If the registrars are in an internal network along with the edge proxy, shouldn't the proxy add the internal address as the Path instead of the public?  
- I am seeing that despite the header Path being added, the registrar is trying to relay the INVITE messages to the UAC and not to the proxy, I am using several parameters of the registrar module in the registrar servers such as: use_path(1), path_mode(0), path_use_received(1), path_chek_local(1). 
- Do I have to still tweak the request manually (that is messing with $du/$ru) in order for the packet to go back to the proxy?


I know these are a lot of questions but if you could maybe guide me to some samples, related issues or documentation I would appreciate it, I am sure that others that encounter these issues might benefit as well.

Saludos,

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Benjamín Visón / IT Engineer / Software Developer
bvisonl@gmail.com / (829)-664-5163




On Thu, Sep 10, 2020 at 9:38 PM E. Schmidbauer <eschmidbauer@gmail.com> wrote:
If you want redundant registrars, you should add an edge proxy (or two if you want redundant edge proxies) and use the path header. This way the user location record includes a "path" back through the proxy which the UAC connected to. 

On Thu, Sep 10, 2020, 7:29 PM Benjamín Visón <bvisonl@gmail.com> wrote:
Hello David,

I am able to get the INVITE go from one kamailio to the other just fine and the call actually connects, the problem arises when, for example, a 200 OK (SDP) message is delivered back to the caller, this SDP doesn't have the necessary information for the ACK to route itself back to the caller. Therefore I am having to keep track of each to/from tag (in an htable) and know on which kamailio those to/from tags are being handled so that I can intercept messages and then re-route them since simply calling t_relay would not work. 

This is getting very messy and there are a lot of cases in which the scenario is not working as desired (for example, a BYE message is behaving very in a very strange manner if the caller is the one that hangs up the call).

If you could get me those PPT I would really appreciate it! I am not a SIP guru but I can defend myself. I just can't seem to understand properly how to route these replies/requests.

If needed, tomorrow I will try to capture a few scenarios with sngrep so that I can share them, I have multiple scenarios with multiple problems but I will try to pick the one that's working the best.


Saludos,

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Benjamín Visón / IT Engineer / Software Developer
bvisonl@gmail.com / (829)-664-5163




On Thu, Sep 10, 2020 at 2:42 PM David Villasmil <david.villasmil.work@gmail.com> wrote:
Hello,

What happens when you send the INVITE from Kamailio1 to Kamailio2? that should work properly. It is a simple call scenario, unless you have some other requirement?
There's even some PPTs showing how that works (which i can't find right now)

Regards,

David Villasmil
phone: +34669448337


On Thu, Sep 10, 2020 at 5:57 PM Benjamín Visón <bvisonl@gmail.com> wrote:
I am setting up a redundant active/active environment and I am in need of having 2 kamailios operate as full proxies (meaning both of them will accept registrations).

I am using DMQ in order to keep htables synched as well as dialogs. 

For locations, I have a PostgreSQL database with the registrations.

My problem is that since both kamailios are accepting registrations the UACs are only able to receive packets from the UAS on which they are registered. Therefore when let's say UAC-1 registers to Kamailio A and it tries to call UAC-2 which is registered on Kamailio B nothing happens because UAC-2 receives the INVITE from Kamailio A and just ignores them.

I've spent almost a month trying to play with inter-kamailio communication (that is, detecting these types of scenarios and sending the INVITE to Kamailio B and have Kamailio B send the INVITE to UAC-2) but there are a LOT of things that are not working properly let alone having to keep track of all the dialog information and to/from tags and doing proper route of all ACK/BYE/CANCEL, etc.

My question is, is there a way to achieve this scenario where multiple kamailios can coexist with all responsibilities? 


Things I've tried:
  • Keep track of to/from tag in an htable and forward requests based on who sent the request
  • Use append_branches to handle multiple AOR (with the possibility of 1 user having multiple registrations in different kamailios)
  • Manually tweaking $ru/$du based on what type of request is and who is it destined to.

Any orientation will be appreciated as this is a crucial piece of the project I'm working on.

Saludos,

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Benjamín Visón / IT Engineer / Software Developer
bvisonl@gmail.com / (829)-664-5163


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