[Freeswitch-users] Load balancing solution using pure FreeSWITCH

[Alfredo Quiroga-Villamil]

Vit:

Nice email, very informative; curious to find out the reasons why you
decided to go with FS instead of OpenSip. We soon have to make a
similar decision and would like to find out the rationale behind it.

Thanks,

Alfredo

On Tue, Mar 16, 2010 at 8:04 AM, Vitalii Colosov <vetali100 at gmail.com> wrote:
> Hi dear FS community,
> After a brief analysis of 2 solutions using OpenSIPS
> and Kamailio (http://www.opensips.org/html/docs/modules/devel/load_balancer.html#id226109
> ) and (http://wiki.freeswitch.org/wiki/SBC_Setup) I decided to implement my
> own solution using ONLY FreeSWITCH and ONLY 1 table of any database server
> (we use MySQL).
> It works on few of our servers right now without any issues.
> Feel free to reuse / improve it or provide your comments if you see
> something wrong with it.
>
> We have one routing server (RS) and several Media Servers (MS).
> FreeSWITCH is installed on each server in default configuration.
> --> MS_1
> RS  --> MS_2
> --> MS_N
>
> (Failover can be implemented by adding one more routing server, but this is
> out of scope of current description).
> Routing server routes calls to media servers based on logic that you can
> easily define.
> (Generally speaking, Routing server can route part of the calls onto itself,
> but to simplify let's say that it will route only to Media Servers).
>
> Routing server is used to register subscribers (it will have directory files
> ./freeswitch/conf/directory/default/10001whatever.xml-99999whatever.xml).
> Media servers do NOT contain files with users (security issue? probably
> should be managed on dialplan stage of media servers by comparing ip
> addresses of requests).
>
> The whole routing can be presented by the following chain:
> Call arrives into Default context-->RS default dialplan-->Lua script-->PHP
> script to get destination MEDIA SERVER IP-->back to Lua script-->Bridge
> "sofia/external/" to determined MS IP address-->[Bridge to fail over media
> server, optionally]-->End
> Let's say we need to route all international calls based on less loaded
> server (other logic can be easily implemented in PHP script as well).
> 1. RS Dialplan: default.xml
> <include>
>         <extension name="route">
>                 <condition field="destination_number"
> expression="^(00)(\d+)">
>                         <action application="lua" data="route.lua $2"/>
>                 </condition>
>         </extension>
> </include>
>
> 2. RS Lua script: route.lua
> called_number = argv[1]; //without "00"
> api = freeswitch.API();
> server_ip_address = api:executeString("curl
> http://localhost/get_server_ip.php);
> forwarding_session_string =
> "sofia/external/"..called_number.."@"..server_ip_address;
> session:setVariable("bypass_media", "true"); //described below!!!
> session:execute("bridge",forwarding_session_string);
> 3. PHP script: get_server_ip.php
> <<<  ANY PHP CODE THAT WILL QUERY COMMON DATABASE AND WILL DETERMINE LESS
> LOADED AT THE MOMENT SERVER>>>
> die($less_loaded_server_ip);
>
> All Media Servers should provide information about their current load into
> one common database (dedicated server or routing server can be used for
> database).
> If you use scripts you can update this table on starting a call and after
> call finished.
> Or you can create a job that will query FreeSWITCH and will update the
> database every, say, 10 seconds.
>
> Basically that's all (really!)
> I beleive it can be used for most general purpose scenarios without need of
> third-party tools.
> P.S.
> The only problem we had from the beginning was that RTP media traffic was
> passing thru both servers: RS and Media Server.
> But after we added the following command to the routing script, RTP media
> traffic started to pass only thru Media server, making RS almost free.
> session:setVariable("bypass_media", "true");
>
>
> Best regards,
> vIT
>
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