[Freeswitch-users] FreeSwitch setup as a "Dumb" SBC

Tue Feb 3 10:47:59 PST 2009

Hi Rod,

Great info, Thanks!
Glad to see others are interested in the same concept.
My reasons for SER as routing core and implementation is slightly different
yet similar.

I like your Redirect model, with that you are truly using your Kamailio as
route server only. I would imagine very scalable.
	- Are you able to do any round robin, serial or parallel forking
with this?
	- I wonder if multiple Contacts in the 302 response maybe with some
logic in FreeSwitch dialplan?
If so I think your design is a bit more efficient than mine as it keeps SER
out of the call path.

My design is little different.. it is more of a "Stateful" setup.  With SER
staying in call path and FreeSwitch at Edge.
I do this to enable Serial Forking to a series of SBCs (FreeSwitch) geo
distributed, when one of the branches is congested it
forks to the next SBC (route).

The FreeSwitch guys are probably right tho... with mod_easyroute and mod_lcr
we could probably implement all of this in FreeSwitch without SER.
I would be curious to know if anyone is doing something similar at high
volumes and what sort of concurrency and cps they
are able to achieve.

I am a Perl and C# guy, I thought about implementing a mod_manged_lcr with
memcached support.
Memcache support would prob boost the scalability by a factor of 10 at
least.

I will let you know if I end up developing a high performance FreeSwitch
route module.
Right now I use memcache in a OpenSIPS perl script for my route caching and
its incredibly fast
and clusters well.

It actually might be easier to add memcached support to mod_lcr and
mod_easyroute but im not real strong in C/C++

I'll jump on IRC later and chat with some of the experts on this as I know
memcache has been discussed before.
I'd be curious to know if any progress has been made there already. 

Regards,
-Adam

-----Original Message-----
From: freeswitch-users-bounces at lists.freeswitch.org
[mailto:freeswitch-users-bounces at lists.freeswitch.org] On Behalf Of rod
Sent: Tuesday, February 03, 2009 1:33 AM
To: freeswitch-users at lists.freeswitch.org
Subject: Re: [Freeswitch-users] FreeSwitch setup as a "Dumb" SBC

Hi Adam,

I'm in the process of using FS as a SBC. For the route lookup, I do it 
using OpenSER carrierroute, without having to flow through 
SBC---Openser---SBC. I'm using carrierroute at this time cause I need 
more than 200 000 routing entries and carrierroute has been tested with 
twice this number.

Here is the setup:

- install openser and carrierroute and make openser listening on 
127.0.0.1:5062 (for example) on your SBC
- populate carrierroute table

What I do to use carrierroute module from FS is to use a specific 
X-header (X-LOOKUP).

In the dialplan, in the default context, I have something like this:
<extension name="LOOKUP_ROUTE">
<condition field="destination_number" expression="(\d+)$">
<action application="set" data="hangup_after_bridge=true"/>
<action application="set" data="continue_on_fail=true"/>
<action application="export" data="sip_h_X-ROUTE=LOOKUP"/>
<action application="bridge" 
data="sofia/internal/${sip_req_user}@127.0.0.1:5062"/>
<action application="export" 
data="sip_h_X-ROUTE=${sip_redirect_contact_host_0}"/>
<action application="transfer" data="${destination_number} XML ROUTING"/>
</condition>
</extension>

The process is simple:
the export "sip_h_X-ROUTE=LOOKUP" had a sip header X-ROUTE=LOOKUP
then I bridge the call to 127.0.0.1:5062 (openser process)

In openser I have a route block that checks the presence of header 
LOOKUP and openser sends a "604: unable to route call" if the prefix is 
not found, or a "302: with the IP of the gateway found"

In FS, you can get the IP using the variable 
"${sip_redirect_contact_host_0}". Then I transfer this to the context 
ROUTING, where the check condition is based on the LOOKUP header that 
has been rewritten with this variable.

I will document all this setup (installation of openser/carrierroute and 
config file of FS and openser) on a wiki page I start writing yesterday, 
so please be indulgent and patient.
The next step is to test the scalability of this.

I'm a very bad programmer, so that's the only way for me to contribute 
to FS, and as I see many people interested for an SBC setup, I think it 
could be great if we share our work/knowlegde.

The wiki page is there:
http://wiki.freeswitch.org/wiki/SBC_Setup

regards,
rod.

Adam Long wrote:
>
> Hi Guys,
>
> I've been working at setting up a couple of FreeSwitch nodes as a 
> topology hiding SBCs that handles both ingress traffic from my
>
> providers/peers and pass traffic up to an openser router that then 
> routes call across the cluster of SBCs through which they reach the 
> destination.
>
> I have OpenSIPS/SER setup doing DB route lookups and ENUM with 
> LCR/Serial forking etc.
>
> My question is what would be the best way to send a call out to a 
> destination choosen by the OpenSER router?
>
> For example:
>
> SIP Provider -- > SBC --- > OpenSER ---- ( route lookup returns 
> 123.123.123.4 as dest ) -- > SBC --- > 123.123.123.4
>
> I was thinking something along the lines of adding a "X-Route-To: 
> +1NXXNXXXXXX@ <mailto:+1NXXNXXXXXX@>123.123.123.4" with openser
>
> and then something like this in the SBC.
>
> <context name="from-sipcore">
>
> <extension name="outboundroute">
>
> <action application="bridge" data="sofia/external/${sip_h_X-Route-To}" />
>
> </extension>
>
> </context>
>
> Is this a wise approach, is there anything I could do to do this better?
>
> I'd like to keep the logic in the SBCs as simple as possible.
>
> I am pretty familiar with SIP but my knowledge fades when it gets into 
> the nitty gritty of routing. ie the Contact: and Via: headers
>
> and all that good stuff.
>
> I should also state I have two profiles defined one for the 
> internal/private "core" network and one for the outside "external" 
> network.
>
> Any thoughts on this at all would be greatly appreciated.
>
> Am I missing something in the SIP spec that would allow for this is a 
> standardized way?
>
> Regards,
>
> -Adam
>
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