Re: 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:[email protected]]
>    Sent: Friday, October 09, 2009 6:33 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
> 
> 
>    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]> 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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-- 
Brian F. G. Bidulock
[email protected]
http://www.openss7.org/