Subject: [Sigtran] M3UA:Unexpected ASPSM/ASTM Message (Jacky Chen)

From: [email-masked]
Date: Fri, 22 Jun 2007 10:15:57 +0800

thanks,brain:

your ansers:

1.a) No, because the ASP is ASP-DOWN for all the other AS.  See the state
diagram in RFC 4666 Figure 3 and the description above the diagram
and the description in 4.3.4.1.  Note that the only transition from
ASP-INACTIVE to ASP-DOWN is using the ASP Down message which results
in the ASP moving to the ASP-DOWN state for _all_ AS.  So, if a given
AS is in the ASP-DOWN state and the ASP receives an ASP Inactive Ack,
_all_ the AS are in the ASP-DOWN state.  Sending an ASP Down message
in this case has precisely the desired effect.

1.b)my new question:
   (1)if ASP is in ASP-ACTIVE Status ,When received unexpected ASP_INACTIVE
ACK Message,

how to do ? send ASP_ACTIVE Message containing the RC(ASP_INACTIVE ACK'S) ?

    (2)  if ASP is in ASP-INACTIVE status ,When received unexpected
ASP_INACTIVE ACK Message,it need send to ASP-INACTIVE Message or do
nothing?
    (3)if ASP is now in ASP-INACTIVE status,When received unexpected
ASP_ACTIVE ACK Message,it enter into ASP-ACTIVE Status or how to do?

  when  these happen,the rfc4666's"then initiate procedures to return
itself to its previous state" can explain these all?
 not need to explain one by one ???

2.a)  Completely reasonable: the SGP is required to send ASP Up Ack in
     response to ASP Up, in which case the ASP Up Ack is always expected
by the ASP, cf. RFC 4666 4.3.4.1.  The only reason for an unexpected
 ASP Up Ack is some sort of error, in which case the procedure will
 attempt to properly resynchronize state.

2.b)my new question:

   when ASP Send ASP-UP Message,But ASP-UP-ACK Message not be sent back
immediately.Then LM maybe ask ASP to Send ASP_DOWN Message
And ASP_DOWN Ack Message is received earler than ASP_UP ACK Message.
  then ASP Will Be Setted into ASP-INACTIVE Status????

3)i think the SGP maybe send ASP-*-ACK Message because of some exception or
data configure change  or SGP Want to synchronizing itselt status with ASP
Using ASP-*-ACK Message ???
      your opinion maybe is more different as mine.

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 21 Jun 2007 21:24:30 -0600

chen.puran,

[email-masked] wrote:                  (Fri, 22 Jun 2007 10:15:57)
> how to do ? send ASP_ACTIVE Message containing the RC(ASP_INACTIVE ACK'S) ?

RFC 4666 Figure 3:

                                      +--------------+
                                      |              |
               +----------------------|  ASP-ACTIVE  |
               |   Other ASP/ +-------|              |
               |   IPSP in AS |       +--------------+
               |    Overrides |           ^     |
               |              |    ASPAC/ |     | ASPIA/
               |              |[ASPAC-Ack]|     | [ASPIA-Ack]
               |              |           |     v
               |              |       +--------------+
               |              |       |              |
               |              +------>| ASP-INACTIVE |
               |                      |              |
               |                      +--------------+
               |                          ^     |
        ASPDN/ |                          |     | ASPDN /
   [ASPDN-Ack/]|                   ASPUP/ |     | [ASPDN-Ack /]
     SCTP CDI/ |              [ASPUP-Ack] |     | SCTP CDI/
     SCTP RI   |                          |     | SCTP RI
               |                          |     v
               |                      +--------------+
               |                      |              |
               +--------------------->|   ASP-DOWN   |
                                      |              |
                                      +--------------+

              Figure 3: ASP State Transition Diagram, per AS

How does it show that you transition from the ASP-INACTIVE to the
ASP-ACTIVE state? (A: send an ASPAC message).  Do you see that?

RFC 4666 Section 4.3.4.3. ASP Active Procedures:

   Anytime after the ASP has received an ASP Up Ack message from the SGP
   or IPSP, the ASP MAY send an ASP Active message to the SGP,
   indicating that the ASP is ready to start processing traffic.  This
   action MAY be initiated at the ASP by an M-ASP_ACTIVE request
   primitive from Layer Management or MAY be initiated automatically by
   an M3UA management function.  In the case where an ASP wishes to
   process the traffic for more than one Application Server across a
   common SCTP association, the ASP Active message(s) SHOULD contain a
   list of one or more Routing Contexts to indicate for which
   Application Servers the ASP Active message applies.  It is not
   necessary for the ASP to include all Routing Contexts of interest in
   a single ASP Active message, thus requesting to become active in all
   Routing Contexts at the same time.  Multiple ASP Active messages MAY
   be used to activate within the Application Servers independently, or
   in sets.

   ...

What do you not understand about sending an ASP Active message?

> ASP_INACTIVE ACK Message,it need send to ASP-INACTIVE Message or do

RFC 4666 Section 4.3.4.4.  ASP Inactive Procedures:

   ...

   At the ASP, the ASP Inactive Ack message received is not
   acknowledged.  Layer Management is informed with an M-ASP_INACTIVE
   confirm primitive.  If the ASP receives an ASP Inactive Ack without
   having sent an ASP Inactive message, the ASP should now consider
   itself to be in the ASP-INACTIVE state.  If the ASP was previously in
   the ASP-ACTIVE state, the ASP should then initiate procedures to
   return itself to its previous state.

   ...

Does this passage say anthing about initiating procedures from the
ASP-INACTIVE state?  (A: no.)

>  not need to explain one by one ???

See RFC 4666 Figure 3 and RFC 4666 Section 4.3.4.4 ASP Inactive
Procedures.

All state transitions and the messages required to effect them are
illustrated one-by-one in RFC 4666 Figure 3.

>   then ASP Will Be Setted into ASP-INACTIVE Status????

ASP Up Ack and ASP Down Ack (ASPSM) messages are both sent ordered on
stream 0.  The ASP Down Ack cannot arrive before the ASP Up Ack when the
SGP follows the protocol.

>       your opinion maybe is more different as mine.

I have already told you that unsolicted ASP Down Ack is for complete
isolation of the SGP at the NIF and unsolicited ASP Inactive Ack for a
partial isolation.  Go back and read through my previous notes.

These procedures are rather simple: I do not know why you seem to be
having such difficulty following them.

--brian

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/