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[SCTP-Discussion] Another situation on Notify Message Treatment


Chronological Thread 
  • From: "Sundaresan M" <sundarem AT future.futsoft.com>
  • To: <bidulock AT openss7.org>
  • Cc: <discussion AT sctp.de>
  • Subject: [SCTP-Discussion] Another situation on Notify Message Treatment
  • Date: Mon Dec 31 06:52:00 2001
  • Importance: Normal
  • List-id: SCTP Discussions <discussion.sctp.de>

Hi Brian and group,

Thanks for the reply. Now I have an entirely different situation.

I am working with Version 06 of M3UA. In this version we dont have the
concept of ASP Identifier to identify individual ASP's. So how can this be
managed (I am designing a conformance suite for M3UA-06 and hence I cannot
use latest versions of M3UA, I have to stick to version 06 only).

As u have said I too was designing the Notify message so that it is sent to
every ASP in the AS except for those ones in the Down state. But, imagine
this situation.

Configuration: Two ASP's and One SG.
ASP1: Already in Active State
ASP2: Working in Override mode, Comes to Active State.

Now once ASP2 comes to Active state SG will send Notify to both the ASP's
with an Status Identification "Alternate ASP Active".

I understand that now SG will stop sending the traffic to ASP 1 from now on.

My questions are: If there is no ASP Identifiers existing to identify ASP's
then how will the ASP1
1) differentiate that he has to stop processing traffic from that SG and
will take further steps to either bring itself to Inactive state if is not
serving anyother AS.
2)know that it is only ASP2 which took over the traffic. But before this, is
there a need for ASP1 to know that ASP2 has taken over the traffic for that
SG.

3) Since ASP2 also recieves this Notify message what if he thinks that some
other ASP had taken over the traffic.

Best Regards,
Sundar.



-----Original Message-----
From: Brian F. G. Bidulock
[mailto:bidulock AT openss7.org]
Sent: Sunday, 30 December 2001 6:38 PM
To: Sundaresan M
Cc:
discussion AT sctp.de
Subject: Re: [SCTP-Discussion] Notify Message Treatment


Sundaresan,

On Sat, 29 Dec 2001, Sundaresan M wrote:

> Hi,
>
> I would like to know how the Motify messages are treated in the Adaptation
> layers like IUA, M3UA etc.
>
> QUESTION 1
> **********
> Configuration 1: One ASP and One SG
> -------------------------------------
> ASP is moving from Inactive state to Active state. Now the AS state
changes
> from AS_INACTIVE to AS_ACTIVE. Will a Notify message be sent by the SG to
> this one and only ASP in the Configuration. Will this treatment change
> depending on the AS_STATE change also. What I mean is, if the state
changes
> from Active to Inactive will this ASP(being the last one in the AS)
receive
> a Notify(AS_PENDING)!!

"A Notify message reflecting a change in the AS state MUST be sent
to all ASPs in the AS, except those in the ASP-DOWN state, with
appopriate Status Information and any ASP Identifier of the failed
ASP." - M3UA-10

A Notify("AS-Pending") "MUST" be sent to the ASP.

>
> QUESTION 2
> ***********
> Configuration 2: Two ASP's (ASP1 and ASP2) with One SG:
> ------------------------------------------------------
> ASP 1 : Active
> ASP 2 : Inactive
>
> Now ASP1 moves from Active to Inactive due to LM primitives. Will the
> Notify(AS_PENDING) message be sent to Both ASP1 and ASP2 serving the SG?
or
> will it be sent only to ASP2.

"If no other ASPs in the Application Server are in the state
ASP-ACTIVE, the SGP MUST send a Notify message ("AS-Pending") to
all of the ASPs in the AS which are in the state AS-INACTIVE."
- M3UA-10

The message "MUST" be sent to both ASP1 and ASP2.

>
> QUESTION 3
> **********
> Will the AS_STATE be maintained in the database by the individual ASP's.

The ASP will need to know what state it is in for each AS that it serves.

>
> QUESTION 4
> **********
> Some Stack implementors say that NOTIFY message treatment is optional.
Does
> this mean that the usage of the Notify itself is optional. If it is so
then
> how will the ASP's know the AS_state and will act on AS_State changes?

Sending of the Notify message is not optional. The response of the ASP to
the
Notify message is not proscribed. There is a difference. Notify messages
are considered advisory in that it is up to the ASP to consider the
information in the Notify message and other information that it has at its
disposal (such as a knowledge of the state of other ASPs) before deciding
what
action to take.

Hope that helps.

--brian






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