Subject: Re: [SIGTRAN] M2PA Questions regarding draft-ietf-sigtran-m2pa-11 and draft-bidulock-sigtran-m2pa-test-04

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Tue, 24 Feb 2004 13:40:57 -0700

Martin,

I have submitted draft-bidulock-sigtran-m2pa-test-05 to the I-D editor.
Until they become available on the ietf servers you can get them from
here:

  http://www.openss7.org/sigtran06.html

The exact links are:

  http://www.openss7.org/docs/draft-bidulock-sigtran-m2pa-test-05.txt
  http://www.openss7.org/docs/draft-bidulock-sigtran-m2pa-test-05.ps
  http://www.openss7.org/docs/draft-bidulock-sigtran-m2pa-test-05.pdf

We are also publicly releasing our M2PA implementation under GPL that
conforms to a test suite written to this document.  Watch the downloads
page for more information.

See the Changes section towards the end of the document for changes from
Version 0.4 to Version 0.5.  (As usual an index appears at the end of the
document.)

More comments below...

On Tue, 24 Feb 2004, Hecht Martin wrote:

> Brian,
> 
> I didn't know whether to write this to the whole IETF mailing list or just
> to you personally.  So I decided to write only to you.

I have copied this response to the sigtran mailing list as your questions
are likely of general interest there.

> 
> This email concerns:
> 
> 1) questions concerning Bad BSN handling 
> 2) questions concerning Bad FSN handling 
> 3) questions concerning tests that refer to Bad FIBR
> 4) question concerning receiving an MSU in the Aligned Ready state
> 
> 1) Question concerning Bad BSN handling
> 
> In test 3.8.10 Abnormal BSN - single Data message, the message is ACK'd and
> sent to L3.
> In test 3.8.11 Abnormal BSN - two consecutive messages
> 
>         Is the first message ACK'd and sent to L3?
>         Is the second message ACK'd and sent to L3 (prior to the link being
> taken out-of-service)?

This test case may need correction.  In the diagram it appears that an
abnormal FSN is being sent rather than an abnormal BSN.

> 
> 2) Questions concerning Bad FSN handling
> 
> In test 3.8.14 Abnormal FSN, it shows that the link is taken out-of-service
> when the abnormal FSN is detected.  In Draft 11, on page 30, it simply says
> that the message is discarded.
> 
>         Should the link be taken out-of-service in this case?

You will see in the new draft that 3.8.14 was removed because it is no longer
applicable for m2pa-11.

> 
> 3) Question concerning tests that refer to Bad FIBR
> 
> Tests 3.3.2,  3.3.4,  3.3.6,  3.3.8,  and 3.8.8 all refer to a Bad FIBR.
> 
>         Since M2PA does not have a FIB, what is the intention here?

You will see in the new draft that 3.3.2, 3.3.4, 3.3.6 and 3.3.8 have been
made non-applicable, because they are not applicable to m2pa-11.

> 
> 4) Question concerning receiving an MSU in the Aligned Ready state
> 
> In test 3.2.4 Unexpected signal units/orders in "Proving" state, an MSU
> (User Data message) is shown as "ignored" if received in this state.  

That is correct.  Under Q.703/Q.781 MSUs are ignored in the Proving state.

> 
> In test 3.2.5 Unexpected signal units/orders in "Aligned Ready" state, it
> does not show the case of receiving an MSU.
> 
>         If an MSU is received in the Aligned Ready state is it ignored? 
>         Or, is the MSU accepted (ACK'd)?  
>         If it is accepted, does it, or can it, replace the need to receive a
> Ready message - will the link go In Service?

See test case 3.1.6 for how Data is addressed in the Aligned Ready state, but
generally, the peer should accept Data when In Service is expected just as
Q.703/Q.781 accepts an MSU instead of a FISU in the Aligned Ready state.

> 
> I hope this isn't too many questions.  I really appreciate any time you will
> spend on this.

Your questions are well in line with the changes made to the document.  Please
review the new document and see if the changes resolve your questions.

--brian

> 
> Best regards,
> Martin Hecht
> Signaling Core Group, Embedded Division
> Comverse, Inc

-- 
Brian F. G. Bidulock    ¦ The reasonable man adapts himself to the ¦
[email-masked]    ¦ world; the unreasonable one persists in  ¦
http://www.openss7.org/ ¦ trying  to adapt the  world  to himself. ¦
                        ¦ Therefore  all  progress  depends on the ¦
                        ¦ unreasonable man. -- George Bernard Shaw ¦

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---

From: Hecht Martin <[email-masked]>
Date: Wed, 25 Feb 2004 10:22:53 -0500

Brian,

Thank you for your response.  Draft 5 clears up the FIBR issue and "part" of
the FSN issue. Your answer to receiving an MSU in the Aligned Ready state
makes that clear.

So, I am left with the following questions/comments.

1) Out-of-order FSN is discarded

If an out-of-order FSN is discarded, then every FSN after that is
potentially out of order and discarded.  The links would fail from Excessive
Delay of ACK.

2) 2 out of 3 Bad BSNs

The question remains whether the messages with the Bad BSN are ACKed and
forwarded to L3 prior to taking the link out of service.

Test 3.8.10 ACKs and forwards the message.  Test 3.8.11 does not show this.
Although it is not that important because the messages will be retrieved on
the peer and not lost.

Thanks again,
Martin Hecht

-----Original Message-----
From: Brian F. G. Bidulock [mailto:[email-masked]]
Sent: Tuesday, February 24, 2004 3:41 PM
To: Hecht Martin
Cc: [email-masked]
Subject: Re: [SIGTRAN] M2PA Questions regarding
draft-ietf-sigtran-m2pa-11 and draft-bidulock-sigtran-m2pa-test-04

Martin,

The exact links are:

More comments below...

>         Should the link be taken out-of-service in this case?

You will see in the new draft that 3.8.14 was removed because it is no
longer
applicable for m2pa-11.

> Ready message - will the link go In Service?

See test case 3.1.6 for how Data is addressed in the Aligned Ready state,
but
generally, the peer should accept Data when In Service is expected just as
Q.703/Q.781 accepts an MSU instead of a FISU in the Aligned Ready state.

> I hope this isn't too many questions.  I really appreciate any time you
will

Your questions are well in line with the changes made to the document.
Please
review the new document and see if the changes resolve your questions.

--brian

-- 
Brian F. G. Bidulock    ¦ The reasonable man adapts himself to the ¦
[email-masked]    ¦ world; the unreasonable one persists in  ¦
http://www.openss7.org/ ¦ trying  to adapt the  world  to himself. ¦
                        ¦ Therefore  all  progress  depends on the ¦
                        ¦ unreasonable man. -- George Bernard Shaw ¦
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