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

I think while restarting the network it is upto the IP layer which get restarted i.e. transport restart and probably the SCTP connection context remains active.

That's why both end keeps on using the existing connection to send Notify and ERROR. So if there any reference in the RFC that a peer can send Notify with AS-PENDING from AS-ACTIVE state?

If yes than what should be the behavior at receiving end?

Regards
Deepak
________________________________
From: Ankit Kumar Sharma [mailto:[email protected]]
Sent: Thursday, October 15, 2009 4:25 PM
To: Deepak Gunjal
Cc: [email protected]
Subject: Re: [Sigtran] In IPSP-IPSP mode what should be the behavior on receving Notify(AS-PENDING) when AS is already AS-ACTIVE

Could you please check why your SCTP layer is not sending connection restart indication to M3UA?
On Thu, Oct 15, 2009 at 10:48 AM, Deepak Gunjal <[email protected]<mailto:[email protected]>> wrote:

It seems that both the end points keeps the connection alive as I can see after network restart Spectra2 sends Notify(AS-PENDING) on the previously established connection and my M3UA stack responds with ERROR(Unexpected-Msg) as the AS state at my stack is ACTIVE. So the ERROR message does reaches to spectra2 and the sequence continues.



I am still not able to figure out how to come out of this loop? As per RFC there is no case where I can receive AS-PENDING for AS-ACTIVE.



Any suggestions?



Regards

Deepak



-----Original Message-----
From: Ashwani Kathuria [mailto:[email protected]<mailto:[email protected]>]
Sent: Friday, October 09, 2009 6:33 PM
To: Deepak Gunjal
Cc: [email protected]<mailto:[email protected]>
Subject: Re: [Sigtran] In IPSP-IPSP mode what should be the behavior on receving Notify(AS-PENDING) when AS is already AS-ACTIVE



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 <[email protected]<mailto:[email protected]>> 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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