Hi, Mike:
Please note the following:
Table 1 shows all parameters that are observed in digitization form. (There may be similarity with some transport level parameters, but these are expressed in a transport independent way.)
A given codec/data (appln.) may or may have all the parameters. If not, those parameters will be NOT be used.
Each parameter contain: Yes/No and Value.
So, the first problem is to express performance/QOS parameters that do NOT contain any values. That is, it will have only the parameters without any value. For example, all audio/video codecs will have their parameters expressed that will have only a limited set (in the previous case as can be seen in Appendix of Annex N - there has been only 4 sets, etc.). These are universal sets and does not matter what the codec type is.
In H.323, we are NOT defining values of the parameters because values are subjective and implementation dependent. The values of any given QOS parameter or a set of QOS parameters are beyond the scope of H.323 (Q.13/16). The values are being defined in other SGs or organizations (e.g., TIPHON, IMTC, etc.).
You are right that the values for each codec will be different. People may define many classes based on values as well. For example, 100ms delay is gold service, 150ms delay is silver service, etc. In Annex N, we will not be addressing those values.
The same is also true for data.
Defining of QOS values of any given parameters is OUT of scope of H.323.
It appears that there is a mis-understanding. I do not any intention for any personal attack other than to complete the work on time (if it appears so, I apologize for this).
Hope this clarifies your questions.
Best regards, Radhika R. Roy
-----Original Message----- From: Mike Buckley [mailto:mikebuckley@44COMMS.COM] Sent: Friday, August 11, 2000 11:08 AM To: ITU-SG16@MAILBAG.INTEL.COM Subject: Re: H.323 QOS
Radhika,
The basic problem is to express the end-to-end H.323 QOS parameters of each medium (audio, video, data) that are applicable no matter what the underlying transport network (or networks) is.
The answer of this problem is Table 1 that I have provided.
We agree on the first paragraph. The problem I have with your Table 1 relates to media statistics (see my earlier comments). Incidentally the columns are the properties of transport media streams. the values will be dependent on media type, codec, packetisation etc. So I am not sure what the relevance of codec or T.120 is in the heading. The parameters in each column are what I regard as the generic bearer descriptor.
Now we have to group those parameters in different combinations for each medium that makes sense from the enduser point of view to satisfy their requirements.
This is the simple problem.
The values follow from the users QoS service request, and the choices made by the application in achieving this (codec type, packetisation, jitter buffer design). Once the application has figured out what these parameters are then the entries in your table can be computed by the application and flagged to the transport operator on a domain by domain basis or end-to-end if there is one homogeneous transport space.
A by-product of this solution needs to satisfy RSVP and ATM QOS as H.323v2/v3/v4 spec is doing today.
I see no conflict with the use of these transport mechanisms in the transport plane. You seem terribly worried about this. What is the problem?
I am surprised to see that you are still saying that your are NOT familiar with H.323. If it is so, we have problems. An editor needs to be on the top of everything because the last editor did a good amount of job in a very short period of time addressing all issues. We are now going backward and losing our valuable time just because the editor is NOT familiar with
H.323.
If you ask questions, I would be happy to answer as much as I can.
You are putting words into my mouth here that I never used. Why the personal attack? I thought the discussion had been quite constructive up to this point.
Mike
Mike Buckley +44-1457-877718 (T) +44-1457-877721 (F) mikebuckley@44comms.com
----- Original Message ----- From: "Roy, Radhika R, ALCOO" rrroy@ATT.COM To: ITU-SG16@MAILBAG.INTEL.COM Sent: Friday, August 11, 2000 2:41 PM Subject: Re: H.323 QOS
Hi, Mike:
The basic problem is to express the end-to-end H.323 QOS parameters of each medium (audio, video, data) that are applicable no matter what the underlying transport network (or networks) is.
The answer of this problem is Table 1 that I have provided.
Now we have to group those parameters in different combinations for each medium that makes sense from the enduser point of view to satisfy their requirements.
This is the simple problem.
A by-product of this solution needs to satisfy RSVP and ATM QOS as H.323v2/v3/v4 spec is doing today.
I am surprised to see that you are still saying that your are NOT familiar with H.323. If it is so, we have problems. An editor needs to be on the top of everything because the last editor did a good amount of job in a very short period of time addressing all issues. We are now going backward and losing our valuable time just because the editor is NOT familiar with H.323. If you ask questions, I would be happy to answer as much as I can.
I like to see other members also provide comments on this.
Best regards, Radhika
-----Original Message----- From: Mike Buckley [mailto:mikebuckley@44COMMS.COM] Sent: Friday, August 11, 2000 9:01 AM To: ITU-SG16@MAILBAG.INTEL.COM Subject: Re: H.323 QOS
Radhika,
I think we are in total agreement until your last two paragraphs. Lets figure out what problem we are solving and what we need to do to achieve this, then examine the issues of backward compatibility.
You are a lot more familiar than I am with the existing H.323 mechansims. Why are these not transport mechansm independent as per your model?
Mike
Mike Buckley +44-1457-877718 (T) +44-1457-877721 (F) mikebuckley@44comms.com
----- Original Message ----- From: "Roy, Radhika R, ALCOO" rrroy@ATT.COM To: ITU-SG16@MAILBAG.INTEL.COM Sent: Friday, August 11, 2000 12:58 PM Subject: Re: H.323 QOS
Hi, Mike:
Let me try again.
What is the reference point of H.323 QOS? Is it not H.323? If it is so, what do we mean by H.323?
The answer is: Audio (different codecs), Video (different codecs), and Data (T.120 applications) that are used by H.323.
What are the QOS/performance characteristics of audio, video, and data from the application point of view that is generated by audio codecs, video codecs, and data (T.120) applications?
These QOS/performance characteristics come from the SOURCE codecs and data applications. Per transport independent H.323 specifications, an enduser express their QOS/performance requirements on end-to-end basis purely from application point of view irrespective of the transport network (e.g., IP, ATM, etc.).
Moreover, H.323 is meant for the packet network, not for any circuit-switched network like PSTN or ISDN.
Let us NOT go beyond this before we start debating transport layer QOS or service provider requirements. These are NOT the concern of H.323. H.323 is the transport independent application.
H.323v2/v3/v4 has also provided mechanisms how RSVP and ATM QOS can be used for H.323 audio, video, and data. So, H.323 QOS that will be defined in H.323 Annex N MUST provide mapping for the backward compatibility. It is a requirement that MUST be met per the norm of ITU-T.
So, what is left for mapping? Mapping is simply a by-product of the above requirement. Mapping is simply a table, nothing else.
Did I miss anything?
Best regards, Radhika R. Roy AT&T
-----Original Message----- From: Mike Buckley [mailto:mikebuckley@44COMMS.COM] Sent: Thursday, August 10, 2000 10:19 PM To: ITU-SG16@MAILBAG.INTEL.COM Subject: Re: H.323 QOS
Radhika,
Thanks for the input which I welcome as I will unfortunately not be present at Portland.
Let me ask a few questions and make a few comments hopefully with the intent of opening up the debate.
1. I am not sure I understand your concept of a mapping table between the H.323 QOS and the transport layer QoS. My understanding is that QoS is on three levels:
a) that specified from a service point of view between the user and service provider (e.g PSTN quality, conference quality etc) This is the domain of the speech experts and can be characterised by Listener Speech Quaklity (MOS), end to end delay, and absolute category rating, R.
b) application specific parameters, (e.g. equipment delays, codec choice and performance, codec frame size, packetisation arrangements, jitter buffer design, overall packet loss etc.) Optimisation of all these will determine what can be delivered in a).
c) transport parameters for a given choice of application parameters. This boils down only to three parameters as far as I cna see: tranport network delay, packet delay variation in the transport network and packet loss in the transport network. Again these parameters will determine the results in a) for a given choice of the parameters in b). These parameters are generic from the perspective of the transport network. i.e the transport network does not need to know the details of the application.
So the sequence of cause and effect and control is:
a) User requests QoS class from service provider, b) Service provider determines application specific parameters in conjunction with users equipment and other service providers, c) Service provider requests required delay, delay variation and packet loss from network provider.
I see no need for mapping here. The only QoS info flows within the application are specific to the application and those between the application (service provider) and the transport network are generic. i.e. delay, jitter and packet loss. Have I missed something?
2. The issue of bit rate and media stream statistics I think need to be decoupled from QoS. These are specified to enable optimisation of resources within the transport network. They have no QoS significance from an application point of view. i.e the apllication does not care about the media stream bit rate and statistics but the transport network provider does as it eats up his resource. They may be used for policy enforcement however in the transport network so they do need to be agreed between service provider and network operator. i.e the network operator agrees to provide a given QoS level (delay, jitter, packet loss) provided the media properties are within an agreed profile (bit rate, flow statistics).
3. The next point is how can the service provider know the statistics of a particular VBR stream? These can only be specified over a large number of similar calls and will depend, for instance, on who is speaking, the nature of the speech interaction etc etc. They can only be measured not calculated. The service provider is in no better position to measure these than the transport network operator and, in fact, where no gateways are involved, may not be able to. On the other hand the class of signal would have to be signalled to the network operator for him to be able to distinguish which class a particular measurement belonged to. e.g voice/speech/data, codec type, conference, multicast etc. So I see no purpose in trying to exchange statistics between the service provider (application) and transport operator. I think peak bit rate is all that can be meaningfully excanged. The specification of media class is however perhaps worth exploring.
4. The controlled category has always puzzled me. I only see two possibilities. Either the requested QoS level is guaranteed (on a statistical basis e.g 95% of all connections over a specified period) or not guaranteed. Is your controlled category a way of saying guaranteed, not to 95% but to some lower figure? If you can't put a percentage on it then it seems it is plain and simple not guaranteed. Anything that is not guaranteed to some specified statistical level is best effort and you can't say anything more about it. So I only see two categories here.
In summary, I think we need to do three things in Annex N.
a) Figure out the QoS information to be exchanged within the Application between service providers and end users. This will go in H.225.0 and H.245.
b) Figure out how we are going to signal QoS and media information between the application (service providers) and transport domains (IP or ATM networks etc). The info is basically delay, jitter, packet loss requirements and peak bit rate. We need a protocol for this.
c) we need to work out the interactions between the application QoS signal flows and the application/transport signal flows. I don't think we need worry about how the transport network mechanisms assure the requested QoS paramerters. RSVP/Intserv, Diffserv, MPLS, ATM, over provisioning are all possibilities.
Would welcome comments and views on the above.
Mike
Mike Buckley +44-1457-877718 (T) +44-1457-877721 (F) mikebuckley@44comms.com
----- Original Message ----- From: "Roy, Radhika R, ALCOO" rrroy@ATT.COM To: ITU-SG16@MAILBAG.INTEL.COM Sent: Thursday, August 10, 2000 10:15 PM Subject: H.323 QOS
Hi, Mike and All:
It is time to discuss about H.323 QOS.
I believe that we have an agreement as follows:
· H.323 QOS MUST be backward compatible to support RSVP and ATM QOS as it exists for H.323v2/v3/v4 · Like H.323 spec, the application level H.323 QOS MUST be independent of the transport layer QOS and should support all transport networks (e.g., IP, ATM) · A mapping table between the H.323 QOS and the transport layer QOS (e.g., IP QOS [DiffServ, RSVP, etc.], ATM QOS [CBR, rt-VBR, nrt-VBR, ABR, etc.]) should be provided.
From the H.323 multimedia application point of view, there are following
performance parameters can be used to characterize the traffic characteristics:
· Bitrate characteristics: Peak bit rate (PBR) or peak rate (PR), Sustained bit rate (SBR) or average rate (AR), minimum bit rate (MBR) or minimum rate (MR), and mean bust size (MBS) · Delay and loss characteristics: end-to-end delay (EED) or delay, end-to-end delay variation (EEDV) or delay variation (DV), and bit-error-rate (BER) or (packet) loss rate (LR)
We can now form a table with all parameters as follows:
Table 1: H.323 Multimedia Application Performance Matrix Audio (codecs)--- Video (codecs)--- Data (T.120) PBR/PR Yes/No/Value Yes/No/Value Yes/No/value SBR/AR Yes/No/Value Yes/No/Value Yes/No/value MBR/MR Yes/No/Value Yes/No/Value Yes/No/value MBS Yes/No/Value Yes/No/Value Yes/No/value EED/Delay Yes/No/Value Yes/No/Value Yes/No/value EEDV/DV Yes/No/Value Yes/No/Value Yes/No/value BER/LR Yes/No/Value Yes/No/Value Yes/No/value
From the above table we will have the opportunity to choose each parameter
for each medium (audio, video, data) that makes sense from the application's and enduser's point of view. Again, these parameters can be specified as follows:
· Guaranteed: The value specified for each parameter MUST be guaranteed. · Controlled: The value specified for each parameter MAY be satisfied as far as practicable (possibly with certain range), but definitely NOT guaranteed. · Best effort: No commitment will be made.
Now each medium (e.g., audio, video, or data) will have different categories of performance matrix depending on its selection criteria and this can also be mapped to RSVP, ATM QOS, and others, if needed.
Once we agree on this format, the next step is to create H.323 QOS signaling messages.
This is my input for discussion in the upcoming Portland Q.13 meeting for H.323 QOS.
I like to see the comments from other members as well.
Best regards, Radhika R. Roy AT&T +1 732 420 1580 rrroy@att.com
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