Maybe I'm missing something about the core infrastructure of Kamailio that makes this impossible, but why does it seem like nobody wants to run multiple Kamailio load balancers in a cluster? sip.yourcompany.com can have A/SRV records pointing to multiple IP addresses of separate Kamailio instances. As long as the edge proxies are either stateless, or transaction-stateful (i.e. not dialog stateful) this should provide both availability and scalability at the edge.

Is there something that makes this infeasible in Kamailio?

On Thu, Jun 30, 2016 at 11:15 AM Giacomo Vacca <giacomo.vacca@gmail.com> wrote:

Hi Daryn,

it may not be an overkill, depending on the constrains you have. For example if the clients can possibly only be instructed to connect to a single public IP address (5.5.5.5 in your example), while you want to be able to scale the Kamailio architecture with multiple instances, then it can be a viable approach. Remember though that the Load Balancer will be your Single Point Of Failure. If the Load Balancer dies, for any reason, the service is not available.

There has been an interesting thread in this mailing list recently, on techniques to provide active/stand-by redundancy to a Kamailio deployment: "High Availability".

Depending on the capabilities of the clients you may consider removing the Load Balancer from the equation and perform DNS-based load balancing across your Proxy/Registrar/PSTN Gw instances. You'd be removing a SPOF, use one fewer machine, and simplify the architecture. This is not always possible to achieve though, because it delegates load balancing and fail over to the clients.

Giacomo

On 30 June 2016 at 17:03, Daryn Johnson <djohnson@telnetww.com> wrote:

I am interested in opinions and suggestions about load balancing with Kamailio.  I work for an ITSP that currently uses Oracle & Broadsoft, and I am working to design and develop an open source solution using Kamailio (Proxy, Registrar, LB) &  other Application/Media servers for more flexibility and freedom :)  Thank you ALL for the work you have put in on Kamailio!

After much reading and configuration I have a Kamailio 'proxy' setup, with endpoints registered using the Registrar module, and calls being sent/received to/from the PSTN. I am interested in separating the Load Balancers from the Registrars & logic, for security and in order to be able to scale appropriately.  I will be using the dispatcher module for both load balancers and proxies using the following architecture:

PublicIP = 5.5.5.5; Private IP = 192.168.1.0/24

USERS (Public Internet) ==> (public: 5.5.5.5)  [ Kamailio (LoadBalancer, Firewall, Sanity Checks) ] (core:192.168.1.2) ==> [ Kamailio Registrar, Proxy, PSTN GW ] ==> AppServers or PSTN GW

(we can access our PSTN gateways Via our Core using Private IPs)

Questions: 

1) Is it overkill to separate the LB & Proxy/Registrars?  

2) Is this a common architecture & anyone configured this architecture successfully? 

Thanks in advance for your help!

Daryn Johnson

Senior VoIP Engineer

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