Re: [SIP] authentication at gateway

"Culpepper, Bert" wrote:
> 
> I understand and agree that support for a signaling protocol inside another
> signaling protocol is highly undesirable.  However, SIP does not support
> mid-call terminal events that I'm aware of.  If we can transporting ISUP and
> QSIG inside of SIP why can't a subset of MGCP and Megaco be transported
> inside of SIP (for those who wish to support it)?

Because ISUP provides information that is very much related to the
function of SIP in the
first place - initiation of sessions between end points. There is a
natural mapping of ISUP
messages to SIP messages for this very reason - both are call
establishment protocols. If you ignore the ISUP, the SIP is still useful
and makes sense by itself. The semantics of the protocol are driven off
SIP, *not* the ISUP in the payload. That is not the case if you tunnel
megaco over SIP.

I would not advocate tunneling DHCP over SIP, HTTP over SIP, or SLP over
SIP, since those protocols 
don't do the same thing SIP does. Same with megaco/mgcp. Tunneling them
over SIP serves no purpose. SIP is not a good transfer protocol (see the
Guidelines for Authors of SIP Extensions:
http://search.ietf.org/internet-drafts/draft-rosenberg-sip-guidelines-00.txt).
Just use the native transport define by the protocol. 

I understand you have an application where you want an app server to
have access to media services provided by an MG attached through a
softswitch. Thats a fine thing to do. I also understand that this
requires megaco/MGCP to be used between the app server and the MG, going
through the softswitch in order to achieve consistency of control. Now,
just because SIP *also* runs between the softswitch and app server, does
not mean that if you also need megaco between them, you should tunnel
megaco through SIP. Just run megaco as an additional protocol between
the two.

-Jonathan R.
-- 
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
jdrosen@dynamicsoft.com                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (732) 741-7244
http://www.dynamicsoft.com

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