Re: What are the chances that SG may not send Notify messages to AS (M3UA)

Chris Benson <[email protected]>
Newsgroups gmane.ietf.sigtran
Message-ID <[email protected]>
Deepak,

I won't estimate "chances" numerically (!), but I'd like
to point out that the Notify message concerning AS state
change is NOT optional but IS compulsory.

Section 4.3.4.5 "Notify Procedures" of RFC 4666 (same as RFC
3332 here) states (in part):

   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.  At the ASP, Layer Management 
   is informed with an M-NOTIFY indication primitive.

I don't see anything optional about this, even in IPSP mode
described subsequently.  Those first three words "A Notify
message" unambiguously refer to the M3UA encoding "on the wire"
from the SGP side.  Indications that are internally generated 
(at the ASP) are distinguished by the name M-NOTIFY, in the 
second sentence above.

Perhaps the implementation which you dispute is referring
to other forms of the Notify message (such as Status Type
"Other"), or perhaps there's a difference reagrding the
time interval over which an AS is in the AS_PENDING state.
I presume that this last (PENDING) mechanism is to stop
unecessary oscillations between AS states as one ASP goes
INACTIVE and another ACTIVE in raspid succession. But
after a configurable time interval, the AS must leave
the AS-PENDING state, and a NOTIFY must be generated
by the SG side, if the longer term AS state has changed.

Good luck with getting those "chances" down to zero.

Chris Benson.

On Wed, 23 Dec 2009, Deepak Gunjal wrote:

>>  Date: Wed, 23 Dec 2009 00:20:28 +0530
>>  From: Deepak Gunjal <[email protected]>
>>  To: "[email protected]" <[email protected]>
>>  Subject: [Sigtran] What are the chances that SG may not send Notify messages
>>       to AS (M3UA)
>>  
>>  Hi,
>>  
>>  
>>  
>>  I want to know that if SG implementations can opt to not send the Notify message for AS state change?
>>  
>>  As per the RFC 4666 sending Notify messages is a SHOULD clause which recommends but not mandate the sending of Notify message unless there are very strong reason to not implement recommended behavior.
>>  
>>  
>>  
>>  In such cases the ASP implementations will be required to shield themselves from such implementations. Although I haven't faced such issue till now but I heard that one of the leading M3UA testing tool vendor has told that their implementation does not send Notify or it can send Notify may be after AS has gone through two or more state changes.
>>  
>>  
>>  
>>  Please suggest.
>>  
>>  
>>  
>>  Thanks and Regards
>>  
>>  Deepak
>>  
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