Hi, Ilyya and Mike:
Please see H.323 Appendix II - Transport Level Resource Reservation Procedure.
The "transportQOS" field simply provides a mechanism who "controls" the transport level resource reservation: Endpoint or GK. Accordingly, the resource reservation is made by that particular entity.
Then each entity can use couple of things related to the resource reservation: 1. BRQ/BCF/BRJ and 2. RSVP (plus ATM QOS for the ATM network as well).
Now, items 1 and 2 are independent. Item 1 is in RAS (pre-call setup phase) and item 2 is in H.245 (call setup phase).
Here is my own interpretation: Item 1 has the abstraction of bandwidth (generic) that can be used on end-to-end basis. That is, this abstraction is independent of the lower transport network. In other words, the total bandwidth that is required for the H.323 application (audio, video, and data) is expressed in the bandwidth field.
However, item 2 is network specific. If there is a single network (either IP or ATM), it may work. If there are two networks (IP + ATM) between the two H.323 endpoints, we have problems to use either RSVP or ATM QOS on end-to-end basis.
In addition, H.323 also provides the abstraction of "circuits: DS0s, etc. (indirectly bandwidth)" in the context of the PSTN-Packet network in Q.931 call setup phase.
H.323 Annex N is addressing this problem to provide end-to-end QOS not only for the bandwidth parameter, but for all other parameters including delay, jitter, bit-error-rate/packet losses for both: 1. Pre-call setup phase (RAS) and 2. Call setup phase (Q.931/H.245).
AT&T is bringing a contribution related to QOS in the upcoming SG16 November'00 meeting.
Best regards, Radhika R. Roy AT&T +1 732 420 1580
-----Original Message----- From: Mike Buckley [mailto:mikebuckley@44COMMS.COM] Sent: Friday, October 20, 2000 6:16 AM To: ITU-SG16@MAILBAG.INTEL.COM Subject: Re: QOS singaling in RAS
Ilya,
We are presently reviewing QoS support in H.323 and a new Annex N to H.323 is in preparation. The current H.323 assumes homogeneity of network transport and QoS mechanisms so the only issues to be considered in H.323 are what type if QoS mechanism is supported in the end point. The new work recognises that transport may involve a variety of transport mechanisms e.g. ATM, IP FR, as well as QoS mechanism, e.g. RSVP, DiffServ, MPLS, some of which may be hidden from the end user.
Maybe other experts could comment on your specific query.
Regards,
Mike Buckley Editor Annex N
+44-1457-877718 (T) +44-1457-877721 (F) mikebuckley@44comms.com
----- Original Message ----- From: "Ilya Freytsis" ifreytsis@CETACEANNETWORKS.COM To: ITU-SG16@MAILBAG.INTEL.COM Sent: Thursday, October 19, 2000 7:46 PM Subject: QOS singaling in RAS
Dear experts, One of the choices of the RegistrationRejectReason (h225 v3) is "transportQOSNotSupported NULL, -- endpoint QOS not supported".
How it should be interpreted since it seems there is nothing
related to transport QOS in registration request PDU itself?
Ilya Freytsis Cetacean Networks
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