Re: Dual registration without Outbound

Paul Kyzivat <[email protected]>
Newsgroups gmane.ietf.sip
Message-ID <[email protected]>

Christer Holmberg wrote:
> Hi, 
> 
>> I think I am missing something here. I presume that the knowledge of
> the UA is limited to:
>> - to proxy addresses
>> - an AOR to register
>>
>> Presumably the address of the registrar is derived from the AOR to
> register by removing the user part. So the UA, when 
>> registering, doesn't specify two different registrars. Whether there
> are two or not is a function of how the proxy routes 
>> the register request. So whether the two registers for the same contact
> go to one registrar or two is unknown to the UA. 
>> In some configurations this would give you redundancy, and in others it
> would not.
>> Then, what causes the UA to register two different contacts? Are the
> wlan contact and the 3g contact registered to 
>> *different* AORs? If not I don't see the point. If anything, I would
> expect that 3g and wlan represent access networks 
>> and hence differing proxies, not AORs or registrars.
> 
> In the 3GPP case different contacts can be registered for the *SAME*
> AOR. 

Not just in 3gpp. That should be true most anywhere. Typically they 
represent different UAs.

The question is: why would a *single* UA establish two distinct contacts 
and register them for the same AOR?

> And, as you say, the edge proxies may be "access network dependent", so
> it may not even be possible to e.g. register the wlan contact via the 3g
> edge proxy, etc.

So you are saying that the contact addresses are themselves access 
network dependent??? So that the ip address of the contact is only 
accessible via a particular access network and proxy?

This *really* isn't the internet, is it!!!

	Paul

> Regards,
> 
> Christer
> 
> 
> 
> 
> 
> 	Thanks,
> 	Paul
> 
> Christer Holmberg wrote:
>> Hi,
>>
>>  > So, you want to register both contacts to both registars, right?
>>  >
>>  > Example:
>>  >
>>  > UA_Contact_wlan ----- OB_1 ----- REG_1  > UA_Contact_wlan ----- 
>> OB_1 ----- REG_2
>>  > UA_Contact_3g   ----- OB_2 ----- REG_1
>>  > UA_Contact_3g   ----- OB_2 ----- REG_2
>>
>>> no, like this:
>>  > UA_Contact_wlan ----- OB_1 ----- REG_1  > UA_Contact_wlan ----- 
>> OB_2 ----- REG_2
>>  > UA_Contact_3g   ----- OB_1 ----- REG_1
>>  > UA_Contact_3g   ----- OB_2 ----- REG_2
>>
>> Now, in your example, if OB_1 and REG_2 fail you don't still don't 
>> have redundancy :)
>>
>>> if outbound does not mandate that UA must register each contact with
>> both ob proxies, my pleasant surprise was a too
>>> early one and ob draft falls back to the useless bin.
>> I don't have the spec in front of me, but I don't think it currently 
>> talks about multiple contacts.
>>
>> I guess this all comes back to Dean's question whether we need some 
>> new text into the draft.
>>
>> In order to avoid delaying the Outbound spec even more, I guess it 
>> could also be an extension draft:"Outbound with multiple contacts", or
> 
>> something like that...
>>
>> Regards,
>>
>> Christer
>>
>>
>>
>>
>>
>> -- juha
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