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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