Subject: [SUA issue 15]: Segmentation/Reassembly/Sequencing Part 3

From: [email-masked]
Date: Thu, 6 Sep 2001 12:01:17 +0300

Sandeep,

> > Considerations also needed for enhancing interface boundary
> > between NIF/SUA and NIF/SCCP for passing this parameter across
> > from SUA to SCCP.
> 
> I don't see what you think would be needed here.  Can
> you propose something?
> 
> Sandeep >> What I mean to say here was, if we could decide 
> that inclusion of segmentation parameter avoids some 
> interworking issues and SUA at ASP should include this in CLDT 
> message. Upper Layer primitives as listed in section 1.6.1
> should be modified to permit this parameter to be passed from 
> SUA to SCCP. Either SUA can add a optional segmentation parameter 
> in N-UNITDATA indication primitive or can have N-CLDT indication 
> primitive.

Requiring SCCP layers to change their interfaces is out of scope
of SUA.  

John

---
You are currently subscribed to sigtran as: [email-masked]
To unsubscribe send a blank email to [email-masked]

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 6 Sep 2001 04:39:53 -0500

Sandeep,

Consider the multiple SG/STP case for Connection-less messages.  The
ASP sends several very large CLDTs which requires segmentation at the
SG.  Some are sent to one SG/STP, some are sent to the other according
to SLS rotation rules.  Both SGs oblige the ASP and segment the messages
into XUDT or LUDT.  To do so, the SG needs to assign an SLR to the
Segmentation parameter in XUDT/LUDT.  Normally in SS7 this SLR value
is assigned by the originating node or segmentation fails.  Normally
this SLR value is selected at the SEP.  If it must be provided at the
SG, the only way to keep the SG from selecting conflicting values would
be one of the following:

  o  Have a fixed portion of the SLR value which is set for each SG
     (e.g., high bit set to 1 for SG/STP A and set to 0 for SG/STP B)
     and each SG only selects the non-fixed bits in the SLR.

  o  Have the ASP provide the SLR value.

The purpose of the Segmentation parameter in CLDT is to permit the
second approach.

Either approach requires modification to SCCP at the SG/STP.  In the
first case, it is necessary to alter the local SCCP user SLR selection
rules.  In the second case, it is necessary to alter the local SCCP user
SLR selection rules.

Once an ASP provides Segmentation parameter, it might as well perform
segmentation if it so desires.  Segmentation parameter is only necessary
for the multiple SG/STP case.

--brian

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

---

---

From: [email-masked]
Date: Thu, 6 Sep 2001 20:22:32 +0530

Brian , John ,

Thanks for clarification, I agree with second approach that Originating SUA node
(ASP in this case) should assign Source Local Reference (SLR) for each CLDT
message and this parameter should be used by SCCP at SG.

About usage of this parameter, I suggest
a) Add parameter segmentation (or SLR alone) in N-UNITDATA primitive at SUA/NIF
interface
b) SUA should recommend that SCCP at SG be enhanced to support this case. This
enhanced SCCP will have "segmentation (or SLR alone)" as optional parameter in
N-UNITDATA primitive. SCCP will be using user passed value of Segmentation Local
Reference (SLR) in LUDT and XUDT messages , that it sends while processing
N-UNITDATA request primitive.

Best Regards,
-Sandeep

"Brian F. G. Bidulock" <[email-masked]> on 09/06/2001 04:09:53 PM

Please respond to [email-masked]

To:   "sigtran" <[email-masked]>
cc:    (bcc: Sandeep Mahajan/HSS)

Subject:  Re: [SUA issue 15]: Segmentation/Reassembly/Sequencing Part 3

Sandeep,

--brian

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

---
You are currently subscribed to sigtran as: [email-masked]
To unsubscribe send a blank email to
[email-masked]

---

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 6 Sep 2001 13:26:21 -0500

Sandeep,

> message and this parameter should be used by SCCP at SG.

The first approach should be permitted as well.  An implementation does not
need SLR if it can derive SLR as described.

> N-UNITDATA request primitive.

SLR identifies the "uniqueness" of the N-UNITDATA primitive, and a such is not
an argument of the primitive.  A sequence number would do.

--brian

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

---