Subject: [Sigtran] SUA questions

From: "Catrou, Laure" <[email-masked]>
Date: Wed, 20 Mar 2002 14:50:52 +0100

Hi,
I have several questions on SUA-draft 12, could you please clarify or point out the right archived answers: 

1) Section 1.5.2 says:
"An ASP routes responses to the SGP that it received messages from; 
   within the routing context which it is currently active and 
   receiving traffic.  The routing context itself is used by the ASP to 
   select the SGP." 
Does this sentence concerns the connection oriented traffic?
For connectionless data flow or first message of connection oriented data flow, a round-robin algorithm for example could be used to select one SGP - and therefore one RC - among several possible SGPs. Am I wrong?
  
2) Section 3.10.9: the interworking values are not clear to me:
- 0 means interworking with IPSP ?
- 1 means interworking with IPSP and SGP ? what kind of SG?
- 2 means interworking with SG-end node ?
- 3 means interworking with SG-relay node ?

3) End of section 4.4.1 says:
"Upon successful registration of an ASP in an AS, the SGP can now send 
   related SS7 Signalling Network Management messaging, if this did not 
   previously start upon the ASP transitioning to state ASP-INACTIVE"
The SNM messaging sent by the SGP in this case is 
- the SNM messages that flows through the SG since the registration is successful     
or
- all SNM messages that recap the SS7 destination states?

4) In section 4.5.1, it is said: 
"The SGP SUA layer determines the set of concerned ASPs to be informed 
   based on the specific SS7 network for which the primitive indication 
   is relevant. In this way, all ASPs configured to send/receive traffic 
   within a particular network appearance are informed.  If the SGP 
   operates within a single SS7 network appearance, then all ASPs are 
   informed."
Why is the Network Appearance parameter not optionally part of SSNM messages as it is in M3UA?
it could allow the identification of the concerned ASs to be splitted and done in the ASPs instead of the SGP.

Best regards, 
Laure Catrou

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Wed, 20 Mar 2002 11:09:39 -0600

Laure,

Catrou, Laure wrote:                                      (Wed, 20 Mar 2002 14:50:52)
> For connectionless data flow or first message of connection oriented data
> flow, a round-robin algorithm for example could be used to select one SGP -
> and therefore one RC - among several possible SGPs. Am I wrong?

The cited paragraph does not preclude a round-robin.  However, the ASP does
not select between RC (AS), it responds in the same context as the RC upon
which messagse have been received.  I wouldn't get too worked up about this
paragraph, it simply implies that AS-SG relations are full duplex (which they
are).

> - 3 means interworking with SG-relay node ?

ASP Capabilities serves no useful purpose.  Both protocol class support
and interworking support can be adequately address with configuration
information.  There is no procedure which uses either field of the ASP
Capabilities parameter.  It has, on occasion, been asked to be removed.
It is an optional parameter.  I just ignore it.

> - the SNM messages that flows through the SG since the registration is successful or

When a subsystem transitions from inaccessible to accessible, as in the
case where an AS becomes active, there is no difference between the SSNM
messages flowing through the SG and the recap.  In fact the SSNM messages
sent by the SG should reflect only the SSNM messages which are pertinent
to the concerned subsystem per normal SS7 SCCP procedures.

> Why is the Network Appearance parameter not optionally part of SSNM messages

Becase it is implied by the RC.

> done in the ASPs instead of the SGP.

Identification of concerned ASP cannot be determined at the ASPs themselves,
it is partially a function of the SCCP layer at the SG.  Would you have us
send all messages to all ASPs and try and let the ASP figure out which AS
to send the SSNM to?  The ASP would require part of the SS7 SCCP management
functions to accomplish this.  This is backhaul: those functions reside at
the SG alone.

--brian

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