Subject: [M2PA] A few questions regarding to changeover...

From: Patrick Lam <[email-masked]>
Date: Thu, 13 Sep 2001 18:25:14 -0700

Hi:

I have the following questions:

1.  On p.35 of draft-ietf-sigtran-m2pa-03.txt (4.2.6 Changeover), part
(a) of what "M2PA shall retrieve from SCTP in order and deliver to MTP3:

(a) any transmitted User Data messages beginning with the first
unacknowledged message with stream sequence number greater than FSNC."

i.  Should M2PA retrieve messages with sequence number greater than FSNC
no matter whether the messages have been acknowledged or not?
ii.  If not, what do we do with an  unacknowledged message with stream
sequence number *smaller* than FSNC?
iii.  Does "unacknowledged" mean "unacknowledged" from the remote SCTP
or remote MTP3?

2.  According to p.46 of draft-ietf-sigtran-m2pa-03.txt (the figure that
depicts Link Change Over procedures), the M2PA has to "locates first gap
in acknowledgements".  However, according to Sockets API Extensions for
SCTP (draft-ietf-tsvwg-sctpsocket-01.txt), I can't find this piece
information in any structs listed in the doc.

So how am I supposed to  "locates first gap in acknowledgements" from
SCTP API?

Thanks a lot in advance,

Patrick.

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 13 Sep 2001 22:27:30 -0500

Patrick,

Proper changeover operation cannot possibly be accomplished in M2PA
using the sockets API.  It is highly questionable whether proper
changeover can be accomplished in M2PA using SCTP.  Simply adding
sequence numbers to M2PA messages would remove all of these
difficulties.

Changeover issues have been raised repeatedly and have not yet been
addressed in the M2PA draft.

--brian

Patrick Lam wrote:                                 (Thu, 13 Sep 2001 18:25:14)

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

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