Subject: [Sigtran] Re: A Query

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Sun, 24 Mar 2002 11:51:10 -0600

Vaibhav,

DUPU corresponds to MTP-STATUS primitive.  This primitive is only
in the SG->ASP (MTP->MTP-User) direction.  At RK granularities at
SI, DUPU is never needed from ASP to SG.

--brian

On Sat, 23 Mar 2002, [email-masked] wrote:

> 
> Hi Brian
> 
>     I was just going through Q.704 and had a doubt. In Section 2.4.1, it is
> written that when the distribution function detects that a received message
> cannot be delivered to the required USER, a UPU message should be returned
> to the originating end on a response basis. Then why is it that in M3UA,
> direction of DUPU is SGP --> ASP? Can't M3UA at an ASP generate the DUPU
> message and send it to the ASP? Or is it because the AS is distributed and
> so we do not really know that AS is overall down or not? But even in this
> case, a few days back you mentioned that an ASP within an AS can be made
> the default ASP and if it goes down, then the AS is down...... So in this
> case, if ASP is that default ASP, then can it generate DUPU?
> 
> Regards
> Vaibhav

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

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From: "Raghavendra Rao.A" <[email-masked]>
Date: Mon, 25 Mar 2002 12:06:09 +0530

All,

Please correct me if my understanding is wrong on any of the
below counts.

   The way M3UA is designed, we are backhauling the M3UA
    user 'after the distribution function' . Otherwise we would
    not be looking at for example, CIC field for routing the
    messages to a particular AS.

   This leads me to my next question ( provided the above
    is correct) .
    If my ISUP traffic is being shared by two AS, i.e. the first
    one processing Even CICs and the second one Odd CICs,
    What should the distribution function on the MTP3 side in SG
    do when the AS controlling odd CICs goes down and the
    AS controlling even CICs is still up ?
    I can not send a UPU since a portion of my ISUP traffic
    can still be backhauled.

    Thanks and Regards

                                            RAGHAVENDRA RAO

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Mon, 25 Mar 2002 02:39:09 -0600

Raghavendra,

Raghavendra Rao.A wrote:                   (Mon, 25 Mar 2002 12:06:09)
>     I can not send a UPU since a portion of my ISUP traffic

This is one of the reasons why M3UA is extremely poor at supporting
ISUP.  Another is not being able to shift CIC assignments on a live
system (ridiculous for any revenue generating application).

To handle the situation you describe smoothly, the SG would have to
maintain some of the common ISUP state machines and reply with
REL/RST indicating unavailability of call control for the affected
circuits and should apply blocking to the affected circuits.  Splitting
of odd and even CICs would be foolish: it will all but destroy ISUP's
circuit group management functions.

Although these things are apparent and have been discussed to a large
degree, they are not well represented in the M3UA spec.

--brian

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

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From: "Raghavendra Rao.A" <[email-masked]>
Date: Mon, 25 Mar 2002 14:40:49 +0530

Brian and Madan,

        Thanks for your inputs.
        I agree that one should not split CICs arbitarily (I just
        chose this particular example 'off the cuff'). Span-wise
        distribution would still be acceptable I suppose.
        Other than having ckt supervision/maintenance
        state m/c at the SG, what would be a better approach ?
        Standby AS entities ?
        My apologies if I am asking questions that have been
        discussed in-detail in the mail-list.
        If there are any specific threads covering these
        issues, let me please know.

        Thanks and Regards

                                         RAGHAVENDRA RAO

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Mon, 25 Mar 2002 03:25:30 -0600

Raghavendra,

A default AS makes sense and was alluded to in M3UA.  What I
described is where the "default" AS resides at the SGP.  This
is the only way to ensure that the "default" AS is always
available.

Another approach would be where load-shared AS are no capable
of handling circuits other that those assigned to them, but
they are quite capable of sending REL/RST for those not under
their control.  But these are implementation specifics.

Ideally, if ISUP state machines are located at the SG, it would
be preferable to have an ISUA protocol (ISUP-User Adaptation Layer)
that would handle these things properly.

--brian

Raghavendra Rao.A wrote:                   (Mon, 25 Mar 2002 14:40:49)

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

---

From: "Tolga Asveren" <[email-masked]>
Date: Mon, 25 Mar 2002 11:53:14 -0500

In corid00 4.1.6.1.2.
(iii) The SPP discards all tagged messages and messages marked for
diversion.

Is the following the correct interpretation:
tagged messages = messages in Category (3) and (4)
messages marked for diversion = messages in Category (1) and (2)

If so, why are messages marked for diversion discarded?

   Tolga

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Mon, 25 Mar 2002 11:42:03 -0600

Tolga,

Well, no, tagged messages and messages marked for diversion
all belong to category (3) and (4).  If you look at, for example,
section 4.2.2.3 you will see that messages marked for diversion
in this card are messages that were "sent" to the ASP (putting
them squarely in category (3) or (4)).  They just have not been
tagged yet.

In the case of 4.1.6.1.2, the only tagged messages are messages
from category (3) and (4) which were tagged during a previous
diversion between SGP of the same SG.

So, the proceure in 4.1.6.1.2 is correct to discard tagged
messages (cat 3&4 messages from previous diversion) as well as
messages marked for diversion (cat 3&4 messages from the current
diversion).  Cat 1&2 messages are neither marked for diversion
nor tagged.  If buffer collection is done with SCTP, they are
just prepended to the normal flow.

--brian

Tolga Asveren wrote:                                        (Mon, 25 Mar 2002 11:53:14)

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