Subject: Re: General Media Descriptor - SDP (and examples)

From: Al Varney <[email-masked]>
Date: Mon, 20 Sep 1999 10:11:49 -0500

At 18:58 09/19/1999 -0500, Nancy-M Greene wrote:
>Christian, This explains the almost empty Local and Remote fields you will
>find in the first Add in the examples! I needed a way to put the network
>type, so tried to build a Local and Remote to hold it, but had to put ANY in
>the sdp as a placeholder for the IP address that the MG would be filling in
>in the reply to the Add. I would agree with Christian that a better way to
>do this is add a LocalControl field that holds the networkType.

   While IP4, IP6, FrameRelay and ATM might be reasonable cases today for
a "networkType", would it be possible to view this from somewhat different
perspective?  In a large gateway, I might have several possible interfaces
of a given technology from which to chose a Local connection, and these
interfaces could be segragated by various agreements/tariffs/policies from
the MGCs viewpoint.  Could LocalControl support choosing among them?

   As a (perhaps lame) example, suppose I have 2 IP4 interfaces; one is
reserved for "high-priority" or VPN (in the circuit-switched sense) calls.
From information known only in the MGC (and not available to the MG), each
connection could select one of those 2 interfaces.  Or the MGC might want
to restrict the range of UDP ports selected by the MG because it "knows"
the far-end MGC/MG has such a restriction.

   The current definition of LocalControl supports only Mode and package-
specific parameters, so my examples look like:

     LocalControl { Package1/Interface=[ATMi3, FRi$] } ; 3rd ATM interface
                                 ; or any FrameRelay interface can be used
     LocalControl { Package1/RTPportRange<10000, RTPportRange>5000 }

   Is this really what is desired -- could there be a 'Package1' whose only
purpose is to supply the packet-side propertyValue(s) used to restrict MG
interface selection alternatives?  Say, a Package named 'PacketInterface'?

>(By the way, the examples are not perfect. I am working on an update of them
>- if anyone else wants to help go through them, or produce a few more to add
>to the examples, please email me!)

   Nancy, I did promise a couple of comments on the examples.  I'll send
them today -- I assume the whole list doesn't want to be involved.

Al Varney - Lucent Technologies  +1 630 224-7493    [email-masked]