Subject: [NSIS] E2E Session level QoS negotiation

From: [email-masked]
Date: Fri, 07 Dec 2001 16:23:09 +0100

Hello,

First of all I would like to thank the authors of
draft-bergsten-e2eqos-questions-00.txt for bringing to everybody's
attention a number of very important 'real life' problems that operators
face concerning end-to-end QoS provisioning.

Secondly I would like to point out that Alcatel and KPN fully support
the views you express in chapter 3.2 of this draft. Indeed there is a
need for 'a means for applications/users to inform each other and
negotiate about the QoS characteristics of the session, prior to its
establishment'. Indeed this requires 'QoS (and probably also charging)
information exchange between customer sites' during session setup. 

In fact what we want is that users can negotiate with each other at
sesion setup time about the level of QoS they want to use for that
particular session. This would allow ISPs to sell QoS "as a service" to
their users. An example could be an ISP offering its customers the
choice between a Gold, Silver or Bronze voice service. Suppose A invites
B to a Silver voice call. If B sees that it is a long distance call from
his mother in-law he might not be interested to accept the call unless
he gets the cheaper (Bronze) rate. On the other hand if A is an
important customer of B ringing him about an important business deal, B
might be even willing to propose A an upgrade of the quality of the call
(on his expense) to Gold. In both cases the ISP providing the telephony
service gains money from the QoS negotiation feature. Without
negotiating a QoS downgrade in the first case B would not have accepted
the call, in the second case the ISP gains more money because B upgrades
the call to a more expensive QoS.

To come back to draft-bergsten-e2eqos-questions-00.txt, in section 3.2
however you hint at using/extending SIP for this purpose. We (Alcatel +
KPN) recently submitted a draft
(draft-bos-mmusic-sdpqos-framework-00.txt) that proposes to specify
extensions to SDP instead of SIP for carrying this kind of QoS
information. There are several reasons why SDP is preferrable over SIP: 
1) users can specify the QoS characteristics PER MEDIUM COMPONENT ->
user might have different QoS requirements for video compared to audio
for example
2) SDP can be used in combination with lots of session signalling
protocols -> in this way the mechanism to negotiate QoS expectations
between end-users can be used not only for SIP services but also for e.g
streaming (RTSP) services
3) you need to synchronise the negotiation of codecs (which inherently
imply some QoS characteristics) with the negotiation of the user's QoS
expectations 
4) SDP offer-answer model already exists (it was invented especially for
the purpose of negotiating end-to-end medium characteristics) -> so why
not reuse this?

Lieve Bos

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From: [email-masked]
Date: Mon, 10 Dec 2001 04:10:25 +0200

Hi Lieve,

> attention a number of very important 'real life' problems 
> that operators face concerning end-to-end QoS provisioning.

Agreed - having service providers' opinions in this work is
very useful.

> however you hint at using/extending SIP for this purpose. We 
> (Alcatel + KPN) recently submitted a draft
> information. 

I read your draft quickly & it is quite interesting.  I think
that I would need to re-read the draft in more detail & come
back with comments.  However, as this is proposing a specific
solution, I think we should wait on it & at first discuss
what we need (i.e. - requirements).

best regards,
John

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From: [email-masked]
Date: Mon, 10 Dec 2001 08:44:21 +0100

Lieve,

> the views you express in chapter 3.2 of this draft. 
Great. 

> however you hint at using/extending SIP for this purpose. We 
Oh, that's clearly a mistake. We intended to write something like
SIP/SDP, indicating that SDP would be involved. We'll correct that in
the future. Thank's for pointing it out. 

Anders

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From: [email-masked]
Date: Mon, 10 Dec 2001 12:24:24 +0100

Hello all,

Indeed, we need to focus on the requirements first. I hope this weeks
session in Salt Lake city will foster some fruitful discussions. The
main reason of my e-mail was not at all to focus on technicalities, but
to point out to all people on the NSIS mailinglist that
draft-bergsten-e2eqos-questions-00.txt really makes a very good summary
of some really important points we need to tackle when talking about E2E
QoS. One of them being the need for 'E2E Session level QoS negotiation'.

Lieve