H.323 Annex E: sequence numbering?

[Manoj Paul]

 Hi All,

 I have a few concerns about H.323 Annex E proposed document.
 My reference is the "Proposed changes to H.323 Annex E"
 document which was presented at Santiago meeting of SG13/16.

 Section E.1.3.2 states Serial Model. It says that Annex E
 stack will wait until a positive reply is returned * for the
 same Session-Identifier *. This means that an outgoing Annex
 E PDU can only contain multiple payloads of the same session
 only. Second, it implies that the sequence number (which is
 present in Annex E PDU header) must be
 unique now across < sender host+port, rcv host+port, session-id>.

 We can not make sequence number unique across <sender host+port,
 rcv host+port> only, because the message sequences should be blocking
 only for same session-identifier, as stated by the NOTE appended
 below section E.1.3.2.

 The Annex E Ack message, however, only contains the sequence
 number of Annex E PDU. How can the sender of an Annex E PDU
 will distinguish for what session's PDU this ack has come for?
 Because sender might have sent Annex E PDUs with the same
 sequence number for different sessions over a given < sender host+port,
 rcv host+port>.

 Am I missing something here. I will appreciate any clarifications
 on the above.

 regards,
 Manoj Paul.