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Re: [Sigtran] In IPSP-IPSP mode what should be the behavior on receiving Notify(AS-PENDING) when AS is already AS-ACTIVE
Deepak,
An SCTP that cannot provide SCTP RI is not usable for
SIGTRAN for this very reason.
--brian
Deepak Gunjal wrote: (Fri, 09 Oct 2009 20:22:59)
>
> Hi Ashwini,
>
>
> Thanks for the response.
>
>
> Now here the problem is that my local SCTP which is nothing but linux
> kernel SCTP (lksctp) has not sent any kind of notification to local
> M3UA that the connection is down due to network restart so my M3UA
> always assumes that everything is up and running fine hence takes no
> action.
>
> My peer is Spectra tool emulating the role of IPSP.
>
>
>
> Now this leads to a situation where both parties assumes they are
> behaving correctly and user data can not be exchanged.
>
>
> Strangely Spectra2 though says that ASP is down but it sends the
> Notify on the existing connection!!
>
>
> Is there a way out to come out of this loop? As per the RFC and
> mentioned section by you I could not found a resolve to this
> situation? Any suggestions are welcome.
>
>
> Regards
>
> Deepak
>
>
> -----Original Message-----
> From: Ashwani Kathuria [mailto:ashwani.grps at gmail.com]
> Sent: Friday, October 09, 2009 6:33 PM
> To: Deepak Gunjal
> Cc: sigtran at ietf.org
> 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
> <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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> >
>
> > _______________________________________________
>
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>
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>
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>
> >
> _________________________________________________________________
>
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--
Brian F. G. Bidulock
bidulock at openss7.org
http://www.openss7.org/