Subject: RE: [Megaco] Megaco Request-Response Help

From: "Kevin Boyle" <[email-masked]>
Date: Fri, 20 Jan 2006 02:30:09 -0500

First, there is no concept of a "call" in H.248. There are contexts that
associate terminations.  These are identified by ContextIDs and
TerminationIDs respectively.  The mostly widely adopted model that I
have seen is to model each half-call as a single context with a physical
termination and an ephemeral termination -- though that it not the only
model, and even within a single MGC there may be several different call
models at any given time.
 
If you wish to track an entire "call", then not only must you track a
context and its terminations, you must also track any other
contexts/terminations that are connected to that context via media
connections between the ephemerals.  For some complex calls, such as
large conferences, you may be tracking upwards of 90 terminations across
30+ contexts!!  Note that calls can also span multiple MGs and/or
multiple MGCs.
 
The short answer is there is no straightforward way to track a "call" in
H.248.  I suggest you worry about tracking contexts.  Remember that the
Move Command moves a termination from one context to another,
necessarily altering that termination's interconnections.  Whether this
constitutes a different"call" or not can be debatable, but it will be
difficult to correlate the new context with the old.
 
Kevin

________________________________

	From: [email-masked] [mailto:[email-masked]]
On Behalf Of Shantanu Das
	Sent: Friday, January 20, 2006 1:20 AM
	To: 'Kumar Saurabh'
	Cc: [email-masked]
	Subject: RE: [Megaco] Megaco Request-Response Help

	Thanks. I too find, the context ID remains same from first
addReply to subtractReply. I have a couple of trace files and by
analyzing those I also draw a conclusion that terminationID also plays a
bigger role. But not sure how far true it is.
	 
	contextID also changed when there is a movRequest. with movReply
a new contextID comes which differ from addReply context ID. Then how to
correlate the 2 contextID here.
	 
	Another Qs is, is the contextID remains unique. I mean to say
that, is there any possibility that it will be duplicated in another
call flow.

	BR
	-Shantanu
	--------------------------------------- 

________________________________

		From: Kumar Saurabh [mailto:[email-masked]] 
		Sent: Friday, January 20, 2006 11:22 AM
		To: Shantanu Das
		Cc: [email-masked]
		Subject: Re: [Megaco] Megaco Request-Response Help

		You can use the context id returned in the first Add
Reply to identify the call. Pass the same context id in all the
subsequent command req (Modify, Subtract ..) in that call.
		
		-Saurabh
		
		Shantanu Das wrote:

			My question is,  a simple call in Megaco
consists of a series of Transcation Requests and Reply. Trans ID is
unique within a Transcation. For addReq/Reply the transcation id is same
but for modReq/Reply the transcation is different. How can I correlates
that this modReq/Reply is for this addReq/Reply. Bcoz I have to identify
a call starting from addReq to subtractReply. If I don't know the
correlation between addReq -> modReq -> subtractReq, I cann't draw the
flow.
			 
			My concern is that, there must be a common
Information Element (IE) that is pass thru in each transcations and
unique to a call. Is anything like this.
			 
			Suggest Pls :)

			BR
			-Shantanu
			--------------------------------------- 

________________________________

				From: Raphael Tryster
[mailto:[email-masked]] 
				Sent: Friday, January 20, 2006 1:37 AM
				To: Shantanu Das; [email-masked]
				Subject: RE: [Megaco] Megaco
Request-Response Help

				The transaction id correlates a reply
with a request. Within a request, you may have multiple actions, each
introduced by a context id, and within each action, there may be
multiple commands, each for one or more terminations.  So you need to
use this extra data to correlate components of the reply with components
of the request.  See some recent emails in this forum about ordering of
these components.

				Raphael Tryster

				"Things should be made as simple as
possible, but not any simpler."  - Albert Einstein

				-----Original Message-----
				From: [email-masked]
[mailto:[email-masked]]On Behalf Of Shantanu Das
				Sent: Wednesday, January 18, 2006 2:47
PM
				To: [email-masked]
				Subject: [Megaco] Megaco
Request-Response Help

				Hi, 
				I am developing an application to
track/identify the requests send from MG to MGC or MGC to MG in Megaco.
The difficulty with me is How to identify which request is for which
response. I mean to say that I received a lots of Request and Response
at a time. How I corelate that this response is received for this
Request.

				There must be (I hope) a unique
Information element(IE) that pass from MG to MGC in request and same IE
with same value comes in Reply from MGC to MG. I am unable to track this
IE. Below I am listing a set of IE that I examined and some times I find
the below IE values are coming in response and some times not.

				TranscationID 
				ContextID 
				TerminatinID 
				Mid 

				So is there any attribute that soley
identify the Request-Response relationship. 

				Regards 
				Shantanu 

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---

From: "Shantanu Das" <[email-masked]>
Date: Fri, 20 Jan 2006 15:10:56 +0530

Kevin,
As per your note (stated in the last paragraph), tracking the contexts will
be the best solution. But I am wondering, the context ID too changes in some
cases. Like a command issued with context id 1 and its reply comes in
context id 2 but both's Transcation id remains same. So I think not only the
contextID but collectively context id, transcation id and termination id
will uniquely track a context/call. Its the programmers intelligence how to
correlate these 3 IE and track.
 
A point
 
1. A Transcation ID (say Trans ID =1 ) issued from MGC to MG can not be
duplicated until unless there is a reply with same trans ID.
    At the same time a Trans ID (Trans ID=1) can not be issued from MG to
MGC with any request (if any new termination added)
    
 Is it true. If so who takes care about the allocation of Trans ID. MGC or
MG. How they track it.
 
Sorry if i bother you :)

BR
-Shantanu

  _____  

From: Kevin Boyle [mailto:[email-masked]] 
Sent: Friday, January 20, 2006 1:00 PM
To: Shantanu Das; Kumar Saurabh
Cc: [email-masked]
Subject: RE: [Megaco] Megaco Request-Response Help

First, there is no concept of a "call" in H.248. There are contexts that
associate terminations.  These are identified by ContextIDs and
TerminationIDs respectively.  The mostly widely adopted model that I have
seen is to model each half-call as a single context with a physical
termination and an ephemeral termination -- though that it not the only
model, and even within a single MGC there may be several different call
models at any given time.
 
If you wish to track an entire "call", then not only must you track a
context and its terminations, you must also track any other
contexts/terminations that are connected to that context via media
connections between the ephemerals.  For some complex calls, such as large
conferences, you may be tracking upwards of 90 terminations across 30+
contexts!!  Note that calls can also span multiple MGs and/or multiple MGCs.
 
The short answer is there is no straightforward way to track a "call" in
H.248.  I suggest you worry about tracking contexts.  Remember that the Move
Command moves a termination from one context to another, necessarily
altering that termination's interconnections.  Whether this constitutes a
different"call" or not can be debatable, but it will be difficult to
correlate the new context with the old.
 
Kevin

  _____  

From: [email-masked] [mailto:[email-masked]] On Behalf Of
Shantanu Das
Sent: Friday, January 20, 2006 1:20 AM
To: 'Kumar Saurabh'
Cc: [email-masked]
Subject: RE: [Megaco] Megaco Request-Response Help

Thanks. I too find, the context ID remains same from first addReply to
subtractReply. I have a couple of trace files and by analyzing those I also
draw a conclusion that terminationID also plays a bigger role. But not sure
how far true it is.
 
contextID also changed when there is a movRequest. with movReply a new
contextID comes which differ from addReply context ID. Then how to correlate
the 2 contextID here.
 
Another Qs is, is the contextID remains unique. I mean to say that, is there
any possibility that it will be duplicated in another call flow.

BR
-Shantanu

  _____  

You can use the context id returned in the first Add Reply to identify the
call. Pass the same context id in all the subsequent command req (Modify,
Subtract ..) in that call.

-Saurabh

Shantanu Das wrote:

My question is,  a simple call in Megaco consists of a series of Transcation
Requests and Reply. Trans ID is unique within a Transcation. For
addReq/Reply the transcation id is same but for modReq/Reply the transcation
is different. How can I correlates that this modReq/Reply is for this
addReq/Reply. Bcoz I have to identify a call starting from addReq to
subtractReply. If I don't know the correlation between addReq -> modReq ->
subtractReq, I cann't draw the flow.
 
My concern is that, there must be a common Information Element (IE) that is
pass thru in each transcations and unique to a call. Is anything like this.
 
Suggest Pls :)

BR
-Shantanu

  _____  

From: Raphael Tryster [mailto:[email-masked]] 
Sent: Friday, January 20, 2006 1:37 AM
To: Shantanu Das; [email-masked]
Subject: RE: [Megaco] Megaco Request-Response Help

The transaction id correlates a reply with a request. Within a request, you
may have multiple actions, each introduced by a context id, and within each
action, there may be multiple commands, each for one or more terminations.
So you need to use this extra data to correlate components of the reply with
components of the request.  See some recent emails in this forum about
ordering of these components.

Raphael Tryster

"Things should be made as simple as possible, but not any simpler."  -
Albert Einstein

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
Shantanu Das
Sent: Wednesday, January 18, 2006 2:47 PM
To: [email-masked]
Subject: [Megaco] Megaco Request-Response Help

Hi, 
I am developing an application to track/identify the requests send from MG
to MGC or MGC to MG in Megaco. The difficulty with me is How to identify
which request is for which response. I mean to say that I received a lots of
Request and Response at a time. How I corelate that this response is
received for this Request.

There must be (I hope) a unique Information element(IE) that pass from MG to
MGC in request and same IE with same value comes in Reply from MGC to MG. I
am unable to track this IE. Below I am listing a set of IE that I examined
and some times I find the below IE values are coming in response and some
times not.

TranscationID 
ContextID 
TerminatinID 
Mid 

So is there any attribute that soley identify the Request-Response
relationship. 

Regards 
Shantanu 

  _____  

This e-mail contains confidential, privileged or proprietary information to
VocalTec Communications.
If you received this messege by mistake, please inform us and then delete
the original and all copies.
*** eSafe scanned this email for viruses, vandals, and malicious content.
*** 
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