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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

To: bidulock at openss7.org, Deepak Gunjal <deepak.gunjal at aricent.com>, Ashwani Kathuria <ashwani.grps at gmail.com>, "sigtran at ietf.org" <sigtran at ietf.org>
Subject: Re: [Sigtran] In IPSP-IPSP mode what should be the behavior on receiving Notify(AS-PENDING) when AS is already AS-ACTIVE
From: Ashwani Kathuria <ashwani.grps at gmail.com>
Date: Mon, 12 Oct 2009 11:41:08 +0530
Delivered-to: sigtran at core3.amsl.com
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References: <BDF44534797E3E46B55F3D12DE0C4BC40322075AD7 at GUREXMB01.ASIAN.AD.ARICENT.COM> <341a09720910090602t320e951ap38b853492c774920 at mail.gmail.com> <BDF44534797E3E46B55F3D12DE0C4BC40322075DA4 at GUREXMB01.ASIAN.AD.ARICENT.COM> <20091009193525.GA375 at openss7.org>

Deepak:

Are you using the latest version of Linux kernel SCTP available. If
yes, you can raise this this issue with them else try using latest
version.

--Ashwani

On Sat, Oct 10, 2009 at 1:05 AM, Brian F. G. Bidulock
<bidulock at openss7.org> wrote:
> 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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>>
>>    >
>>
>>    > _______________________________________________
>>
>>    > Sigtran mailing list
>>
>>    > Sigtran at ietf.org
>>
>>    > https://www.ietf.org/mailman/listinfo/sigtran
>>
>>    >
>>      _________________________________________________________________
>>
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>
>> _______________________________________________
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>
>
> --
> Brian F. G. Bidulock
> bidulock at openss7.org
> http://www.openss7.org/
>

Follow-Ups:
- Re: [Sigtran] In IPSP-IPSP mode what should be the behavior on receiving Notify(AS-PENDING) when AS is already AS-ACTIVE
  - From: Deepak Gunjal

References:
- [Sigtran] In IPSP-IPSP mode what should be the behavior on receving Notify(AS-PENDING) when AS is already AS-ACTIVE
  - From: Deepak Gunjal
- Re: [Sigtran] In IPSP-IPSP mode what should be the behavior on receving Notify(AS-PENDING) when AS is already AS-ACTIVE
  - From: Ashwani Kathuria
- Re: [Sigtran] In IPSP-IPSP mode what should be the behavior on receiving Notify(AS-PENDING) when AS is already AS-ACTIVE
  - From: Deepak Gunjal
- Re: [Sigtran] In IPSP-IPSP mode what should be the behavior on receiving Notify(AS-PENDING) when AS is already AS-ACTIVE
  - From: Brian F. G. Bidulock

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