Re: [MMUSIC] draft-guenkova-mmusic-e2enp-sdpng-00.txt
Juan-Carlos.Rojas@alcatel.fr Fri, 15 March 2002 15:41 UTC
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From: Juan-Carlos.Rojas@alcatel.fr
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Subject: Re: [MMUSIC] draft-guenkova-mmusic-e2enp-sdpng-00.txt
To: "Mandato, Davide" <mandato@sony.de>
Cc: suresh.leroy@alcatel.be, Andreas Kassler <kassler@informatik.uni-ulm.de>, Teodora Guenkova <guenkova@vs.informatik.uni-ulm.de>, mmusic@ietf.org, Eisl Jochen <Jochen.Eisl@icn.siemens.de>
Date: Fri, 15 Mar 2002 16:37:32 +0100
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Hi Suresh, Andreas, Davide et al, I have the feeling that you are not so far from each other, and that we are here tackling a problem of terminology. So I will try to avoid the term "QoS" even if this is QoS discussion. First of all, you need to define the service and the ideal delivery possibilities. Just defining the service you are already defining quality parameters. For example: the image on a screen in a cinema room is by far better than what you can obtain at home with your television set. I'm already hearing the answer: these are two different services. In our case, I guess that, e.g., a voice service will not be defined with the same parameters (e.g., bandwidth) than an audio music service that can be compared to listen a CD at home. But the answer is the same as previously: these are two different services. Therefore, when you define a service, you need to determine which will be the tools and related parameters to be used: codec, frames per second, etc. This does not preclude to define the same service with several levels of perception from the end-user (and therefore, using different codecs, etc.). Once you defined the service in technical terms (codec, fps, etc.) you can associate to it some Traffic Information, that is a description of what you need in an ideal transport environment. And finally, as reality is not always as wonderful as we can dream, you need to indicate how sensible can be the stream to delays, jitter, loss, etc., that is, you need to associate some Sensitivity Information. These are also the reasons why we don't use the term "QoS parameter" in draft-bos-mmusic-sdpng-qos-00, but Traffic Information and Sensitivity Information. All this information has to be shared/exchanged between users, service providers, etc. maybe negotiated and finally agreed. Once everybody is happy at the session/application level, you need to ask your bearer level to reserve resources, setup connections, etc. and you will surely use all or almost all this information to derive the characteristics of the bearer you will request. Obviously, I agree with the remark of Davide, you will negotiate at the application level what you want to do, and next you will go down to the bearer level to ask for resources to try to actually do what you already agreed at the application level (maybe using NSIS protocol or any other method). Best regards, Juan Carlos "Mandato, Davide" <mandato@sony.de>@ietf.org on 15/03/2002 15:15:43 Sent by: mmusic-admin@ietf.org To: Suresh LEROY/BE/ALCATEL@ALCATEL cc: Andreas Kassler <kassler@informatik.uni-ulm.de>, Teodora Guenkova <guenkova@vs.informatik.uni-ulm.de>, mmusic@ietf.org, Eisl Jochen <Jochen.Eisl@icn.siemens.de> Subject: Re: [MMUSIC] draft-guenkova-mmusic-e2enp-sdpng-00.txt Dear Suresh >>> You say that application-QoS is not codec specific but >>> media dependent, correct? I guess Andreas meant that a given application-level QoS defines the set of applicable codecs and their parameters. In contrary, a given codec allows only to support a limited set of application-level QoS. And surely, application-level QoS specification has to be media dependent. >>> The QoS contract between service user and a service >>> provider specifies >>> applications-QoS requirements and contraints, correct? >>> If the previous statements are correct, this would mean I >>> can use a very >>> high-bandwidth with e.g. 20fps or the newest lowbandwidth >>> codec also at 20 fps >>> and in both cases it would be compliant with my QoS >>> contract although in the >>> first case I'm consuming N times more resources. Again, this statement is correct, if we interpret a "service provider" as a distributed multimedia service that provides the user on an end-system with multimedia streaming services. To this extent, we assume a "service provider" as an entity that provides an "abstract service", whose QoS is defined by a set of parameters. Such service provider offers its service to a "service consumer", e.g. an user or an application. For example, from a sheer application-level perspective, we can model stream receivers as "service consumers" and stream senders as "service providers". From a system-wide perspective, though, the distributed multimedia system itself as a whole can be seen as a "service consumer" of more fine-grained services, for example a network transmission service, a capture service, a compression service, and so on. A comprehensive QoS negotiation scheme thus involves 3 roles: the negotiation initiator ("offerer"), the negotiation responder ("answerer"), and the underlying service provider. The negotiation of application-level QoS is a business among "offerer", "answerers", and the providers of services (e.g. capture service, a compression service, etc.) available locally at *all* of the end-peers. Whereas the negotiation of QoS for the network traffic flows is a business involving *in addition* the transport service provider(s). It is the task of the multimedia system to map user QoS parameters into application-level QoS ones (e.g. frame rate, frame size, visual quality). Once the negotiation at application-level is completed, the multimedia system maps the negotiated application-level QoS into QoS parameters for the internal services that it uses, e.g. the network transmission service. The negotiation of QoS for the network traffic flows takes place and the reservation can (eventually) be applied according to whatever mechanism is used (eventually, the ultimate solution that will appear from the NSIS work). Only at this point, the _transport_ service provider comes into play. Furthermore, a requirement for the E2ENP is to carry out network reservations in a coordinated manner among end-peers, to avoid that *network* resources (which, in a distributed system, are those shared the most) are pointlessly reserved when the end-peers themselves have not sufficient resources for carrying out the given multimedia service. This means that the end-to-end negotiation of capabilities and application-level QoS among end-peers should take place in combination, or even a priori, of the negotiation of QoS for the network traffic flows, as well as of the network resource reservation. And the aforementioned requirement also means that the network resource reservation process is the very last step in the session establishment process. Summing up: the user does not care about what codec is actually used, as long as her/his requirements are satisfied. However, when it comes to paying, knowledge about used bandwidth may become an issue. Based on the codecs that have been agreed upon during the capability negotiation, the multimedia system would map the negotiated application-level QoS into traffic spec and act as service user of the network transmission service provider,... >>> If I were an provider I wouldn't care about the codec used >>> or the frame-rate, >>> what interests me are the resources this users is going to >>> use (the traffic QoS) You are absolutely right, that's what the _network_ service provider cares all about. >>> I your mail you state "The provider simply does not care, >>> if I send video at 20 >>> fps or at 5 fps as long as I comply to my agreement." What >>> is exactly this >>> agreement? I guess Andreas meant that the agreement is "how much traffic one sends over the network". >>> >>> But don't understand me wrongly I think the application-qos >>> is very useful data >>> (especially 'only?' for the end-users). However in my >>> opinion we need both >>> application and traffic QoS. Sure, we are completely on the same track. Nevertheless, there is a need to coordinate application-level QoS and the QoS for the network traffic flows. That's what the E2ENP tries to help to achieve. The E2ENP allows agreeing on capabilities and application-level QoS, and then to proceed with agreeing on QoS for the network traffic flows. But the latter is a business of NSIS or IntServ/RSVP, or DiffServ. Alternatively, the E2ENP also allows one using best effort services only. Of course, in this case, since there is no reservation for the QoS for the network traffic flows, the application QoS is likely to suffer. Kind Regards Davide ________________________________________________________________ Davide Mandato Principal Engineer <<mailto:mandato@sony.de>> Broadband Wireless Technologies Research (BWTR) Sony International (Europe) GmbH Tel: +49-(0)711-5858-797 Stuttgart Technology Center Fax: +49-(0)711-5858-468 Heinrich-Hertz-Str. 1 70327 Stuttgart, Germany <http://www.sony.de> <http://www.sony-europe.com/> ______________________________________________________________ _______________________________________________ mmusic mailing list mmusic@ietf.org https://www1.ietf.org/mailman/listinfo/mmusic _______________________________________________ mmusic mailing list mmusic@ietf.org https://www1.ietf.org/mailman/listinfo/mmusic
- [MMUSIC] draft-guenkova-mmusic-e2enp-sdpng-00.txt Teodora Guenkova
- Re: [MMUSIC] draft-guenkova-mmusic-e2enp-sdpng-00… suresh.leroy
- Re: [MMUSIC] draft-guenkova-mmusic-e2enp-sdpng-00… Andreas Kassler
- Re: [MMUSIC] draft-guenkova-mmusic-e2enp-sdpng-00… suresh.leroy
- Re: [MMUSIC] draft-guenkova-mmusic-e2enp-sdpng-00… Mandato, Davide
- Re: [MMUSIC] draft-guenkova-mmusic-e2enp-sdpng-00… Juan-Carlos.Rojas