Subject: RE: H.320,H.323, and MBONE gateway.

From: HERSENT Olivier CNET/DSE/CAE <[email-masked]>
Date: Tue, 24 Feb 1998 19:49:58 +0100

The profiling work around those documents is done at ETSI project TIPHON
( and also also at IMTC ). The last meeting was at San Jose last week.
You can find all details on www.etsi.fr/Tiphon.
Most companies active in the H.323 field are there, from carriers to
clearinghouses (Transnexus), from small companies to giants like Cisco
or Microsoft.
Indeed the H.323/225/245 specs leave many options, but TIPHON recommends
the use of some of them ( for instance the GK routed model, and the
FastStart sequence).
Regarding SIP, it is the hope of many implementors that there will not
be compeeting standards. H.323 has been optimized already in v2 to
improve set-up time (FastStart, H.245 tunelling), and there will be more
efforts in the next versions. Rather than re-do everything from scratch,
it seems a good option to improve the existing standard.

You can buy a H.323 stack from Radvision, Lucent/Elemedia or Databeam,
or rewrite it yourself. But you will need an ASN1 compiler... I've heard
from some manufacturers that they evaluate the development work needed
to be around 4 man/year. Many companies have done it from the ITU
documents, so it is feasible, but I would recommend that you attend
those ITU or TIPHON meeting to get a chance to talk to the people who
actually made the standard. Another option is to wait for NT5, which
will probably have an H.323 stack.

			best regards,

			Olivier HERSENT
		IP telephony technical project manager

France Telecom			tél : +33 2 31759329
Branche développement / CNET	fax : +33 2 31735626
Direction des Services aux Entreprises		Email :
[email-masked]
Services & Protocoles Intranet

> ----------
> De : 	Jon Crowcroft[SMTP:[email-masked]]
> Date :	Wednesday, February 18, 1998 10:24 AM
> A :	Michael Benson
> Cc :	Peter Hoermann; Michael K. Sewell; mbone;
> [email-masked]
> Objet :	Re: H.320,H.323, and MBONE gateway.
> 
> 
> In message <00cc01bd3bcf$aceb1b00$010101c8@pent150>, Michael Benson
> typed:
> 
>  >>Don't count on it... most companies having any type of H.323 stack
> are
>  >>capitalizing on the fact that the standard was done in the ITU and
> is
>  >>extremely poorly documented, and requires people (and/or companies)
> to work
>  >>with existing companies in order to get any projects working.  As a
> result,
>  >>stacks are going for around $100K plus royalties in many
> circumstances.
> 
> the point about documentation is a good one - the documents leave it
> EXTREMELY open to interpretation exactly how a 323 system would be
> configured to use MCs and so on......i suspect that in fact, 323 comes
> from a very smal lnumber of companies who have a detaield model they
> don't want to write down
> 
> the proper way to use standards (politicxally correct) would have
> profiles of the configurations and examples of the message flows....so
> that one could construct a system with soem sort of idea that it might
> interwork.....while there is copious deailt on the ASN for 245 and al
> lthe adjunct protocols, the actual _distriobuted_ operation of the
> overal components is simply not captured anywhere....this is what
> leads one to build systems to montitor and trace and pretty print all
> the messages from what systems there are that one can get - but
> having to reverse engineer a standard from an implementaiton (and the
> free/affordable oens are pretty terrible) is a damning inditement of
> the people that wrote the spec...
> 
> sorry guys, maybe 323 is the best thing since sliced white bread, but
> you couldn't tell from looking at a piece of it that landed butter
> side down:-)
> 
> cheers
> 
> jon
>

---

From: Jon Crowcroft <[email-masked]>
Date: Wed, 25 Feb 1998 00:16:51 +0000

In message <[email-masked]>, HERSENT
 Olivier CNET/DSE/CAE typed:
 >>or rewrite it yourself. But you will need an ASN1 compiler... I've =
 >>heard

you can buy an ASN 1 compiler from us :-)

SIP takes about 2 mm to implement...or you can have source code from
several people for free....

 >>will probably have an H.323 stack.
 
hmmmm - souds like its by definition unnecessarily complex (we had
packet multimedia conferencing sysems in 1988 that took around 3 Man
years

 >>		IP telephony technical project manager

how many times:

H.323 is a CONFERENCING standard (part of a large suite for ISDN
conference systems extended to include non QoS guaranteed LAN packet
conferncing), not an IP _telephony_ standard

hey, its not even WAN internet aware...

telephony is MUCH easier than conferencing.
a telephone costs around 5 dollars in the UK...that is the baseline
(well that is the additional price of a palmtop that features IP
telephony....) ...not attendence at ITU or tiphon meetings...

hey, what does H.323 contribute on user, terminal or number
portability? what about alternate IP packet WAN loss
tolerant encodings? what about security with a standard that is open
to public scrutiny? what about multiple rate receivers? what about
seamless integration of applications without invoking another standar
(e.g. T.120).....

H.323 is fine, in its place....

but it would be REALLY helpful, if someone published a pretty printer
for the "packets on the wire"...i am fed up of trying to hack it from
tcpdump+pepy....
 
 >>
 >>France Telecom			t=E9l : +33 2 31759329
 >>Branche d=E9veloppement / CNET	fax : +33 2 31735626
 >>> Date=A0:	Wednesday, February 18, 1998 10:24 AM
 >>> A :	Michael Benson
 >>>=20
 >>>=20
 >>>=20
 >>>  >>extremely poorly documented, and requires people (and/or =
 >>companies)
 >>> to work
 >>>  >>with existing companies in order to get any projects working.  As =
 >>a
 >>> result,
 >>>=20
 >>> configured to use MCs and so on......i suspect that in fact, 323 =
 >>comes
 >>>=20
 >>> profiles of the configurations and examples of the message =
 >>flows....so
 >>> that one could construct a system with soem sort of idea that it =
 >>might
 >>>=20
 >>>=20
 >>>=20
 >>>=20

 cheers

   jon