Subject: [Sigtran] (M2PA) link status messages should be received and processed during LPO

From: [email-masked]
Date: Tue, 17 Sep 2002 14:43:29 -0400

Hello All,

M2PA v6 section 4.1.4, 2nd paragraph, last sentence:

      (During LPO...)
      "M2PA shall stop receiving incoming messages from SCTP."

In my opinion this should be changed to read:

      (During LPO...)
      "M2PA shall stop receiving incoming User Data messages from SCTP."

A node experiencing local processor outage should continue to receive
and process LSO (and other links status messages), otherwise the M2PA
state machine could get out of synch with its peer.

Regards,

Jeff

_______________________________________________
Sigtran mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/sigtran

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Tue, 17 Sep 2002 13:37:59 -0600

Jeffrey,

I propose to strike the sentence altogether.  Or, rewrite it to say:

    (Dunring LPO...)
    "M2PA shall stop acknowledging received User Data messages."

In LPO M2PA should not stop receiving any messages whatsoever.  What it
should do is stop *acknowledging* received messages to its peer.  The
purpose of withholding acknowledgement is so that the peer keeps its
copy of messages (not delivered to MTP3 because of LPO) so that they may
be redirected onto an alternate link should the LPO persist to the point
of link failure.

This sentence is a just hanging around from when we did not have
sequence numbers.  When we didn't have sequence numbers, the only way to
attempt to avoid msus getting stuck on the wrong side of the link was to
somehow try to get SCTP to stop receiving and acknowledging them.  Now
that we have sequence numbers, it is the M2PA acknowledgements that need
to be withheld and M2PA can collect messages from SCTP as per normal.

You will see this in sections 3.1.9, 3.4.1 and, 3.8.9 of
draft-bidulock-sigtran-m2pa-test-02.txt.  These tests clearly indicate
that the M2PA in LPO cannot be expected to acknowledge receipt of
messages.  What M2PA does internally with regard to SCTP is its own
business now.  This is completely consistent with Q.703 behavior.

--brian

[email-masked] wrote:                 (Tue, 17 Sep 2002 14:43:29)

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