[Serusers] SIP to AS communication

[Dragos Vingarzan]

Hi Klaus,

Yes, it is quite necessary. The P-CSCF's main functionality is to 
firewall the home domains. As such, it has to maintain a registrar for 
those users and that has to be a reversed one - it is not resolving 
identities to contacts but contacts to identities. This registrar is 
kept in sync with the one on the S-CSCF by P-CSCF subscribing to the 
"reg" event at the S-CSCF (see RFC3680).

Also it is responsible for the securing the communication with each 
individual client and of course for making sure that all UEs play nice 
by following Service-Routes and Record-Routes and by not injecting any 
attack traffic into the IMS core network.

The path extension is there already. On the P-CSCF it's a matter of 
adding it to REGISTER. Then the S-CSCF uses it when routing any requests 
towards the P-CSCF and the P-CSCF uses it to identify the session case. 
The processing of requests is quite twisted and my config files are 
already quite long.

Also adding more things to the Path is possible, like a Topology Hiding 
node, used to hide the information from the visited network.

-Dragos


Klaus Darilion wrote:
> Dragos Vingarzan wrote:
>> On this topic, some parts of other modules are pasted in. For example 
>> the pcscf includes some nathelper functionality. I know that the best 
>> thing would have been to just use the nathelper module, but the pcscf 
>> has its own reversed-registrar, as usrloc is not suitable.
>
> Hi Dragos!
>
> Is it really necessary for the PCSCF to have a location table? I 
> thought the Path: extension will take care of routing incoming calls 
> to the clients and stateless proxies can be used as PCSCF.
>
> btw: do you have added support for the Path extension?
>
> regards
> klaus
>
>
>


-- 
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Dipl. Eng. Dragos Vingarzan
FOKUS/NGNI
Kaiserin-Augusta-Allee 31
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We could change the world if God would give us the source code...
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