On Tue, Mar 16, 2010 at 1:04 PM, Vitalii Colosov <vetali100@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 is your single point of failure, you should make two of them in active/standby mode. What about registered endpoints ? ... where do you register them?.... you should have a DB replication in order to have the "registered context" distributed between both routing servers

So, i'd suggest to bring up a LAN_HA and have a floating address between your routing servers.... of course the you should be using ODBC in the core to have registrations on both servers.

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).

you will be loosing calls on the on the MS if it goes down ... maybe there is a way to "replace" media resource for that calls and keep them going even after the MS went down.

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).

consider ODBC in the core!

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);

do your bridging in the dialplan not from a script... you will get better performances!

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");

anyhow it is a good start ... with a custom module for media server "kepalive" and resource migration it could be a great solution.