Re: [Sigtran] In IPSP-IPSP mode what should be the behavior on receving Notify(AS-PENDING) when AS is already AS-ACTIVE

[Ashwani Kathuria <ashwani.grps at gmail.com>]

Hi Deepak,

I think your M3UA stack is correct in sending the Error message but
your underlying SCTP should send some restart or down indication to
your M3UA stack.

5.2.1.  1+1 Sparing, Withdrawal of ASP, Backup Override
...
   Note: If the SGP M3UA layer detects the loss of the M3UA peer (e.g.,
   M3UA heartbeat loss or detection of SCTP failure), the initial ASP
   Inactive message exchange (i.e., SGP to ASP1) would not occur.

So peer M3UA is correct in sending NOTIFY (AS-PENDING) messages but

in section 4.3.3
   If the M3UA layer subsequently receives an SCTP-COMMUNICATION_DOWN or
   SCTP-RESTART indication primitive from the underlying SCTP layer, it
   will inform the Layer Management by invoking the M-SCTP_STATUS
   indication primitive.  The state of the ASP will be moved to ASP-
   DOWN.
and in section 4.3.4.5
   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
   appropriate Status Information and any ASP Identifier of the failed
   ASP.

The question is:
As per section 4.3.3 M3UA should change the ASP to DOWN upon detecting
SCTP failure and as per section 4.3.4.5 NOTIFY messages are not sent
to DOWN ASPs. So why in section 5.2.1 NOTIFY messages are sent to DOWN
marked ASPs?

-- Ashwani


On Fri, Oct 9, 2009 at 2:53 PM, Deepak Gunjal <deepak.gunjal at aricent.com> wrote:
>
> Hi,
>
>
>
> Here is the brief description:
>
>
>
> I am running my application emulating the role of a AS having 2 ASP in override mode. Out of 2 ASP one ASP is ACTIVE and other is down.
>
>
>
> My application has sent the ASP-ACTIVE to peer IPSP node and received the Notify(AS-ACTIVE). Now I restarted the IP network services and as a result remote IPSP node marks the state of my AS as down and sends an Notify(AS-PENDING) which my M3UA stack treats as “UNEXPECTED” message and does nothing as it has not received any notification from SCTP that connection was down so it keeps the local AS ACTIVE and responds with ERROR  message with error code “UNEXPECTED message”.
>
>
>
> My question is what should be my behavior when AS-PENDING is received?
>
>
>
> Regards
>
> Deepak
>
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