H.225 Annex G

Douglas Clowes dclowes at OZEMAIL.COM.AU
Thu Sep 3 18:55:26 EDT 1998


Yes, I have been following it. Since H.323 is possibly comming second to
SIP in everyone's mind, they are not addressing Gatekeeper-to-Gatekeeper
Communication at all.

They are, however, addressing gateway location, or call routing, or path
selection type issues. There is also a lot of debate on whether QoS factors
into this or not, and if so how.

There are a number of proposed solutions to their still-debated problem

One is for IP routers to route e.164 addresses in the same way as they do
IP packets. In this scheme, gateway advertisements would occur via a
modified IP routing protocol (BGP I think it was).

Another, recent proposition, was to use what I call "broadcast storm",
where a gateway send a location request to each gateway it knows about, and
each gateway that can't resolve the call sends the request, ... It was
called "Bidding Algorithm" by the submitter.

The one that appears to have the most support is from Anne Brown of Nortel
<Anne.Brown.arbrown at nt.com>
, which seems to propose a "Trusted, Third Party, Top Level Service
Provider" concept called "Internet Telephony Directory Service Provider" or
ITDSP. I think they have an implementation under construction, targetting
prototype in 1Q99 and market in 2Q99. The proposed solution is for a
database server, and access methods including DNS, LDAP and X.500 DAP, plus
http. It seems that the result of the query might be a pointer to another
server. There may be multiple requests to obtain resolution of a query and
return all information needed for call establishment. Document attached.

Jonathan D. Rosenberg of Lucent Technologies <jdrosen at bell-labs.com>,
submitted a paper (
00.txt ) setting out some requirements, with a view to a location server
for gateway location.

Both of these latter propositions are "Back-End Service" like proposals,
which could relate to Annex G (IMO).



At 08:36 03/09/98 -0600, Glen Freundlich wrote:
>Has anybody looked at any of the iptel work to see if it's applicable to
>H.225.0 Annex G? I've not yet reviewed any of the material so can't
>comment. There is a framework document and some others to be found at
>http://www.bell-labs.com/mailing-lists/iptel. Additionally, there are
>some viewgraphs at
>Glen Freundlich                           ggf at lucent.com
>Lucent Technologies                       office: +1 303 538 2899
>11900 N. Pecos                            fax: +1 303 538 3907
>Westminster, Colorado 80234  USA
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