Subject: RE: [Sip] I-D ACTION:draft-ietf-sip-outbound-03.txt

From: "Christer Holmberg \(JO/LMF\)" <[email-masked]>
Date: Fri, 24 Mar 2006 12:45:02 +0100

Hi Juha, 

>>What if both ISP A and ISP B have an outbound proxy, and you do your
DNS  
>>lookup based on the AoR of the registrar in ISP C. Again, will you use

>>private ISP A DNS servers (or private ISP B DNS servers) in order to  
>>find the appropirate outbound proxy?
>>
>huh, i didn't know that ISP DNS servers are nowadays private.  my AoR
is sip:[email-masked].  are you saying that if i make a dsn query 
>
>host -t SRV _sip._udp.tutpro.com
>_sip._udp.tutpro.com SRV 0 0 5060 sip.tutpro.com.
>
>in ISP A network, i may get some other result than the ne above?  if
so, there is nothing left of open internet.

What I am saying is: if your outbound proxy is located in the ISP A
network (evil.walled.garden.com), and you do the DNS lookup based on ISP
C (free.and.open.tutpro.com), where your registrar is located, how will
the DNS return the address of a outbound proxy within the
evil.walled.garden.com domain?

I don't think we can assume that the outbound proxy and the registrar
are the same thing, or that they are located in the same domain/AoR.

And, what I mean by "private DNS server" was a server which is only
valid for routing within ISP A. For example, a DNS lookup on an ISP C
AoR would return the address of a node (the outbound proxy) in ISP A.
No, I didn't say that is what you should do - I was simply asking if
that is what you meant. But, obviously not :)

Regards,

Christer

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---

From: Juha Heinanen <[email-masked]>
Date: Fri, 24 Mar 2006 14:34:05 +0200

> evil.walled.garden.com domain?

i have said already two times that in the default common case, there are
no walled gardens or firewalls that would prevent outbound sip traffic.
so please stop asking me what to do in your cow milking environment.
the default case assumes open internet.

 > are the same thing, or that they are located in the same domain/AoR.

in the default common case we can assume that the registrar and outbound
proxy for a domain are the same. this what most SIP phones on the
market assume today and i haven't seen any problems with it.

i understand that in walled gardens this may not work, but for those
environment you are welcome to do something more complicated that the
default operation.

-- juha