Re: T.38 session name in examples

Thanks for explanation.if "s" line is optional only in MGC->MG direction
and not in MG->MGC
but then I see that those attributes ( o,s,t ) are missing in reply from
gateway. 
Now I have following doubt regarding this,
1) Should MG send RFC 2327 conformant SDP to MGC in reply ( eg. adding
missing o,s,t lines )
2) or is it MGC which has to manage these missing attribute and add it
to SDP which is to be sent out to remote side.
 
 
Example From Page No. 78 and 79
 
MGC to MG1:
====================
MEGACO/1.0 [123.123.123.4]:55555
Transaction = 11 {
Context = $ {
Add = DS0/1/1 {
Events = 1 {al/on, ctyp/dtone }
}, ; SCN termination prepared to listen for tones
Add = $ {
Media {
Stream = 1 {
LocalControl { Mode = ReceiveOnly, ReserveGroup = True, ReserveValue =
True},
Local {
v=0
c=IN IP4 $
m=audio $ RTP/AVP 18 0
v=0
c=IN IP4 $
m=image $ udptl t38
}; IP termination for audio } }}}}

Reply from MG1 -> MGC
=====================
 
MEGACO/1.0 [124.124.124.222]:55555
Reply = 11 {
Context = 2000 {
Add = DS0/1/1, ; SCN termination added
Add = RTP/1 {
Media {
Stream = 1 {
Local {
v=0
c=IN IP4 124.124.124.222
m=audio 2222 RTP/AVP 18 0 ;MG1 supports both offered codecs
a=ptime:20
} ; IP termination added }}}}}

 
Regards,
Rahul Ruikar
Alcatel-Lucent
Email: [email protected]
Alcanet: 2721 4732
 

________________________________

From: Kevin Boyle [mailto:[email protected]] 
Sent: Tuesday, May 13, 2008 2:38 AM
To: RUIKAR RAHUL A; [email protected]
Cc: Schwarz Albrecht
Subject: RE: [Megaco] T.38 session name in examples


This misconception continues to pervade, and it is worrisome.
 
The s= line (and other mandatory portions of the SDP specification) are
*NOT* optional in H.248.  They are only optional in the MGC->MG
direction.  In communications from the MG to the MGC, the SDP must be
conformant to RFC 2327.  
 
The text in Clause 7.1.8 is explicit that the exceptions to SDP are
valid only in the MGC->MG direction.  This is to allow the MGC to
provide over- or under-specified SDP.
 
Kevin

________________________________

From: [email protected] [mailto:[email protected]] On Behalf
Of RUIKAR RAHUL A
Sent: Sunday, May 11, 2008 6:07 AM
To: [email protected]
Cc: Schwarz Albrecht
Subject: [Megaco] T.38 session name in examples


Just an observation about ITU-T Rec. T.38 (09/2005)
according to SIP RFC "s" line in SIP messages is mandatory, it is
missing in examples 
given in document. 
Though for H248 this attribute is optional but for messages
sent/received from/to SIP agent 
shall have session name attribute present.
 
 
Regards,
Rahul Ruikar
Alcatel-Lucent
Email: [email protected]
Alcanet: 2721 4732

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