[OpenSIPS-Users] B2b module topology hiding

[Anca Vamanu]

Douglas Lane wrote:
> Hi Anca,
>
> I was wondering about that because I saw the tm:t_uac:next_hop part 
> pointing to the RURI, and then attempts to lookup the domain and SRV 
> records.
>
> I also noticed that my script was sending two 100 trying messages, which 
> after removing my manual sl_send one, i was still getting a 100 trying 
> message even though my t_relay has 0x01 flag set.
>
> Can I assume the following then:
> An INVITE from a UAC to the OpenSIPS SBC should only ever call the 
> b2b_init on replies from the OpenSIPS Router server, as that is the 
> topology we want to hide.
> Calls originating from the OpenSIPS Router server must also call the 
> b2b_init for topology hiding.
>
> Or have I missed the boat here?
>
> Thanks
> Doug
>
>   
Sort of like missed it, sorry.
I will try to make things clear. b2b_init_request has to be called on 
initial Invite requests. By calling this function you tell the B2BUA to 
handle this dialog, to put itself in the middle of the call and 
establish different dialogs with the two parties of the call. This is 
the only function and only time that you need to call it to have 
topology hiding working.

If you want to hide the OpenSIPS Router which is staying behind OpenSIPS 
SBC, then you should call b2b_init when the requests come from the Router.

Regards,

-- 
Anca Vamanu
www.voice-system.ro



> On 2010/05/26 11:53 AM, Anca Vamanu wrote:
>   
>> Hi Douglas,
>>
>> First there is an important thing that you misunderstood: if you call
>> the B2B topology hiding on a request, that request should be dropped
>> after not sent on the other side. The B2BUA will generate a completely
>> new request with the information from the first one but putting itself
>> as the Contact and not including the route headers. This request will be
>> routed according to the information in RURI and if it points to the same
>> machine, you will receive this message in the script. You can apply
>> different routing logic by checking if src_ip and src_port equal the ip
>> and port of the machine.
>>
>> Regards,
>>
>>    
>>     
>
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