Subject: [Sigtran] M2PA 6: message acknowledgement

From: Andrew Booth <[email-masked]>
Date: Wed, 04 Sep 2002 13:54:14 -0400

Hi Tom,

I have a question about the message acknowledgment put forward in M2PA 
draft 6.  The following is from section 4.2.1

If there is no other User Data message to be sent when there is a
message to acknowledge, M2PA may send a User Data message with no data
payload. The FSN for this empty User Data message is incremented as
with any other User Data message.

My concern is that the FSN for the empty user data is incremented.  This 
is different behaviour than for FISUs, and means:
1) These empty User Data messages need to be acked just like normal Data 
messages, then the acks need to get acked, etc..  If you completely stop 
sending traffic on an M2PA link, the acks end up bouncing back and forth 
forever (or until the link drops).
2) When directly bridging between MTP2 and M2PA the FSNs get out of sync 
faster, so the FSN mapping becomes slightly more complicated.

Would it be better if the FSN were not incremented for data 
acknowledgement messages, or if we used a different message type (still 
sent on the data stream)?

Thoughts?
Andrew

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Wed, 4 Sep 2002 12:56:06 -0600

Andrew,

I agree.  The FSN should not be incremented.

--brian

Andrew Booth wrote:                                                                 (Wed, 04 Sep 2002 13:54:14)

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/