Subject: Re: [NSIS] One framework or architecture issue

From: Fan Changpeng <[email-masked]>
Date: Mon, 5 Nov 2001 10:47:13 +0100

Hello Jussi,

> It looks to me, that we can not expect one single QoS mechanisms to be
> deployed everywhere in the near future (here I refer to the actual
> mechanisms, not signaling). For example, some operators may stick to Best
> Effort + overprovisioning, while others go for different kind of DiffServ
> schemes or perhaps IntServ. 

I think you are beginning to touch one of the architectural issues: signaling of QoS
requirements can be totally independent of QoS provisioning at different segments
of an end-to-end path.

IMO, following issues have to be dealt with in realizing QoS end-to-end:
(I1) Where does the QoS request come from, or, who triggers the QoS request?
(I2) What entities are informed about the request and how they get informed?
(I3) How to decide the eligibility of the request?
(I4) How to provision and maintain the requested level of QoS?
(I5) What are the other accompanying or follow-up effects of the QoS provision 
such as relevant charging?

In one segment (domain), issues I2, I3 and I4 are quite often closely related to 
each other and are treated in a tightly coupled manner. This is especially the case
when the signaling path and the transmission path afterwards are assumed to
take the same path. For example, as in the cases of ST2+ or RSVP+IntServ.

However, for NSIS, it may be necessary to assume that the signaling path and the 
transmission path are (or can be) independent and different. This would allow, 
for example, that the siganling happens among some bandwidth borkers in the 
relevant domains while the intra-domain signaling and provisioning can be done 
in other ways.

A simplified/modified version of RSVP, which is totally independent of IntServ 
semantics, may well serve the purpose of interdomain signaling while the intra-domain 
provisioning can be done differently. 

Best regards.

Changpeng

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