Subject: Questions About MEGACO/H.248 Version 16

From: Xiuping Qiu <[email-masked]>
Date: Tue, 29 Feb 2000 17:46:31 +0800

Hi,All

I meet some questions when reading MEGACO/H.248 Version 16.

1. In Appendix A

Step 23: "  The MGC now sets up both MG1 and MG2 to be ready to detect the next off-hook event. See step 1. Note that this could be the default state of a termination in the null context, and if this were the case, no message need be sent from the MGC to the MG. Once a termination returns to the null context, it goes back to the default termination values for that termination.  "

I wonder how to implement the  default state, e.g. request MG to detect the offhook event. And even if this were the case,I suppose messages also need be sent from the MGC to the MG to ask MG to detect offhook event because the RequestID now is different from the previous one.

2. In 7.1.6 Stream Descriptor

" StreamIDs are of local significance between MGC and MG and they are assigned by the MGC.  Within a context, StreamID is a means by which to indicate which media flows are interconnected:  streams with the same StreamID are connected  "

I am wondering whether StreamID will conflict  with Topology.

Let's  suppose there are 2 Terminations ( T1 and T2)  in a context . There is one stream on the 2 Terminations each but the StreamIDs are different. So  the media flows are not interconnected. But if the Topology Descriptor of the Context is
Bothway”, What will happen?

3  In  6.2.5  Root Termination

" Root thus may have properties and events (signals and statistics are not appropriate for root).  "
“
It is rather easy  to imagine  events of   normal Terminations.  But I cannot think of  a case of using events for Root.  Can you  give an example ?  And what events may a Root have ?

4  In  7.1.1  Specifying Parameters

"  Unspecified mandatory parameters (i.e. mandatory parameters not specified in a descriptor) result in the command responder retaining the previous value for that parameter.  Unspecified optional parameters result in the command responder using the default value of the parameter.      Whenever a parameter is underspecified or overspecified, the descriptor containing the value chosen by the responder is included as output from the command.  "

Queston:
It seems that "optional" “ here is not the same as that in Annex A defined in ASN.1.  Will you   expain them in detail? And what's the difference between "Unspecified Optional"  “ and  "Optional" . ”.And how to identify a unspecified parameter as mandatory or optional?

When a  Termination is Subtracted from a  Context, the Topology  should be changed, but how? There is no description in the protocol .

Thanks,
Xiuping Qiu
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Xiuping Qiu
Huawei Technologies Co., Ltd.
Mail to:   [email-masked]
Tel    :   +86 755 654 4482
Visit  :   http://www.huawei.com.cn
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