Subject: [Sigtran] SCTP Payload Protocol ID for IUA & DUA

From: "Michael Mentz" <[email-masked]>
Date: Thu, 28 Jul 2005 15:26:35 +0100

Afternoon all,

Just looking for clarification on a paragraph of the DUA specification
:-

"
4.0 Use of SCTP Payload Protocol ID 
As an option, IUA value for SCTP Payload Protocol ID MAY also be used
for DUA, for instance, if one wanted to backhaul ISDN and DPNSS over the
same SCTP association.  However, use of separate SCTP Payload Protocol
IDs (10 for DUA and 1 for IUA) is recommended as the primary option even
in scenarios where ISDN and DPNSS are backhauled over the same SCTP
association. 
SCTP Payload Protocol ID of "10" SHOULD be used for DUA if only DPNSS is
backhauled over a SCTP association - i.e., in scenarios where
simultaneous backhauling of ISDN and DPNSS over the same association is
NOT required 
The SCTP Payload Protocol Identifier is included in each SCTP Data
chunk, to indicate which protocol the SCTP is carrying. This Payload
Protocol Identifier is not directly used by SCTP but MAY be used by
certain network entities to identify the type of information being
carried in a Data chunk. The User Adaptation peer MAY use the Payload
Protocol Identifier as a way of determining whether the message is for
IUA or DUA. 
"

My understanding relates to a scenario where backhauling IUA and DUA
over the same SCTP association is required.

Would I be right in thinking that the SCTP association can contain one
IUA association backhauling the QPTM and DPTM messages to different
Interface ID's? - This appears to be a valid configuration?
Or is the implication that the SCTP association will actually contain
two separate IUA and DUA associations either running on different ports,
or the same port with routing done on PPID. 
Is there a preferred option? I see no reason why QPTM and DPTM cannot be
backhauled over the same IUA RFC3057 association...

My thinking is that if there were separate IUA and DUA associations,
then the same Payload Protocol ID's would apply to all message classes
(ASP,QPTM), 
but if you are running DPTM and QPTM in the same IUA association, then
which would you use for message classes such as ASPSM, ASPTM, do we just
choose one and use it throughout? 
Is it's use negated due to the fact that we do not need to select
IUA/DUA in the first place.

Many Thanks if anyone can help clarify...

Mike Mentz

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---

From: Michael Tuexen <[email-masked]>
Date: Thu, 28 Jul 2005 18:25:16 +0200

Dear all,
could someone explain why you can not use an IUA PPID if you are using 
IUA and
and DUA PPID when using DUA. If you want to, you can send both on one 
association.

What is the benefit from sending DUA messages with an IUA PPID? (At 
least ethereal
will consider the DATA chunk carrying IUA)

Best regards
Michael

On Jul 28, 2005, at 16:26 Uhr, Michael Mentz wrote:

> for DUA, for instance, if one wanted to backhaul ISDN and DPNSS over 
> the same SCTP association.  However, use of separate SCTP Payload 
> Protocol IDs (10 for DUA and 1 for IUA) is recommended as the primary 
> option even in scenarios where ISDN and DPNSS are backhauled over the 
> same SCTP association.
>
> SCTP Payload Protocol ID of "10" SHOULD be used for DUA if only DPNSS 
> is backhauled over a SCTP association - i.e., in scenarios where 
> simultaneous backhauling of ISDN and DPNSS over the same association 
> is NOT required
>
> two separate IUA and DUA associations either running on different 
> ports, or the same port with routing done on PPID.
>
> Is there a preferred option? I see no reason why QPTM and DPTM cannot 
> be backhauled over the same IUA RFC3057 association...
>
> which would you use for message classes such as ASPSM, ASPTM, do we 
> just choose one and use it throughout?
>
> Many Thanks if anyone can help clarify…
>
> Mike Mentz
>
>
>