Re: Multiple Streams and mutiplex terminations

Hello Christian,

If we use SDP, an example could be:

MEGACO/1 [123.123.123.1]:11111    (MG <- MGC)
  Transaction = 10 {
    Context = $ {
       Add = ISDNTerm/*BA17-BA18-PRI1*/D/$ {
           Media { Stream = 1
                    {
                       Local { v=0
                           c=ISDN SAPI 16 BA17
m=data TEI 1 PLP
c=ISDN SAPI 16 BA17
m=data TEI 6 PLP
c=ISDN SAPI 16 BA18
m=data TEI 3 PLP
c=ISDN SAPI 16 PRI1
m=data TEI 9 PLP
} } },
Add = HDLCPW1 {
           Media { Stream = 1 {
               # ---Descriptores Local/Remote-- } } }
  } }

Here, I found two serious problems:

+ We are defining a termination which has ISDN D-channels from different 
physical interfaces/UNIs (BA17-BA18-PRI1 indicates UNI BRI "17", UNI BRI 
"18" and UNI PRI "1"). I think it contradicts the definition of 
terminationss proposed by H.248.1.

+ We are describing several SDP flows (m=) in the Local Descriptor, but 
these flows are multiplexing in their respective channels D (the 
situation is not that: aflow is transmitted and, until it ends, no other 
flow is transmitted; But all flows are simultaneous transmitted, being 
differentiated by the header of the LAPD frames).


If we use MeGaCo properties to specify the TEI and SAPI, it would have 
the same problems.

Javi


El 28/10/2011 3:23, Christian Groves escribió:
> Hello Javi,
>
> I'm not aware of any SDP that would allow you to specify the TEI and 
> SAPI. Probably the closest draft to doing this was Tom's draft 
> http://tools.ietf.org/id/draft-taylor-mmusic-sdp-tdm-01.txt.
>
> Rather than use SDP you probably need to create a new package with two 
> properties that allow you to indicate the SAPI and TEI. Each property 
> would be a sub-list allowing you to indicate with SAPIs and TEIs apply 
> to the stream. You probably wouldn't need multiple StreamIDs in this 
> case.
>
> Regards, Christian
>
> On 25/10/2011 10:51 PM, Javi Muñoz wrote:
>> Hello Christian,
>>
>> Thank you for your answer.
>>
>> I understand MeGaCo syntax doesn't support adding streams in the 
>> multiplex descriptor neither including N in the multiplex descriptor.
>>
>> [Christian] A little, I understand the termination aspect. I'm still 
>> not sure about the streams. I don't understand how you can have 
>> multiple H.248 streams for the circuit termination TermA and TermB? 
>> With what information element (i.e. property) do you assign the SAPI 
>> and TEI to a Stream? What properties distinguish the Nx64K 
>> termination from a HDLCW1 one?
>> [Christian] I'm not 100% sure what you're trying to do but if you're 
>> only using a single Termination to represent each D-channel and a 
>> single Termination for the HDLCPW it seems to me that you don't need 
>> a mux termination and that it may be sufficient to simply use a 
>> property to assign TEIs to Streams (or Terminations).
>> [Christian] I think you're trying to solve this at a different level 
>> than what it should be. The multiplex descriptor describe the 
>> multiplex of terminations used to make up a stream. It doesn't 
>> describe what's happening at a stream level itself. We have the 
>> Stream Descriptor with associated (Local, Remote, LocalControl 
>> descriptors) to do this.
>>
>>
>> In ISDN, each D-channel (channel of 16 or 64 kbps) transport multiple 
>> flows muliplexed by its TEI and SAPI in the Q.921 header.
>>
>> Every of these flows may need to be transported to a different server 
>> in the IP network, and each server may receive only a HDLCPW. So, I 
>> need to multiplex multiple D-channel flows in each HDLCPW. In each 
>> HDLCPW, each flow would be distinguished by its TEI/SAPI and 
>> D-channel identifier.
>>
>> I can not think how to describe in SDP (Local, Remote, LocalControl 
>> descriptors) what D-channel flows must be transported by any HDLCPW. 
>> May you proposed an example?
>>
>> Regards,
>>
>> Javier Muñoz
>>>>
>>>>
>>>>>
>>>>>
>>>>>
>>>>> Regards,
>>>>>
>>>>> Javi Muñoz
>>>>>
>>>>>
>>>>> El 20/10/2011 11:12, Christian Groves escribió:
>>>>>> Hello Javi,
>>>>>>
>>>>>> Did you see my email on the 18/10 which discusses this? Even with
>>>>>> the clarification of the Terminations there's some questions.
>>>>>>
>>>>>> Regards, Christian
>>>>>>
>>>>>> On 20/10/2011 7:38 PM, Javi Muñoz wrote:
>>>>>>> Does MeGaCo support the next contexts?:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Tmux1=Mux(1x64K(TermA/StreamID=1,TermA/StreamID=2,TermB/StreamID=1)) 
>>>>>>>
>>>>>>> -- * -- TermC (HDLCPW1)
>>>>>>>                                     |
>>>>>>> TermA (ISDN D-Channel, UNI p)       |
>>>>>>>    StreamID=1 (SAPI 16, TEI r)------|
>>>>>>>    StreamID=2 (SAPI 16, TEI s)------|
>>>>>>>                                     |
>>>>>>> TermB (ISDN D-Channel, UNI q)       |
>>>>>>>    StreamID=1 (SAPI 16, TEI r)------|
>>>>>>>    StreamID=2 (SAPI 16, TEI s)------------|
>>>>>>>    StreamID=3 (SAPI 16, TEI t)------------|
>>>>>>>                                           |
>>>>>>>
>>>>>>> Tmux2=Mux(1x64K(TermB/StreamID=2,TermB/StreamID=3) -- * -- TermD
>>>>>>> (HDLCPW2)
>>>>>>>
>>>>>>>
>>>>>>> where:
>>>>>>>
>>>>>>> (a) Every multiplex termination is multiplexing Streams from
>>>>>>> different ISDN terminations, and only any Streams of each
>>>>>>> termination.
>>>>>>>
>>>>>>> (b) The result of the multiplexion must be a flow of "64 kbps".
>>>>>>>
>>>>>>> Javi Muñoz
>>>>>>> _______________________________________________
>>>>>>> Megaco mailing list
>>>>>>> [email protected]
>>>>>>> https://www.ietf.org/mailman/listinfo/megaco
>>>>>>>
>>>>>> _______________________________________________
>>>>>> Megaco mailing list
>>>>>> [email protected]
>>>>>> https://www.ietf.org/mailman/listinfo/megaco
>>>>>>
>>>>>
>>>>>
>>>>
>>
>> _______________________________________________
>> Megaco mailing list
>> [email protected]
>> https://www.ietf.org/mailman/listinfo/megaco
>>
>

_______________________________________________
Megaco mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/megaco