Re: sending ASP UP in IPSP SE

SJ,

The short answer is that it doesn't matter much, and all
is well if both sides try to come UP around the same time,
providing that each receiver of an ASP Up responds with
an ASP Up Ack.

The state of each IPSP is maintained by the remote (not 
local) peer M3UA layer.  When one IPSP wishes to enter 
the UP/Inactive state, it issues a ASP Up message, 
indicating that it is ready for its state to be changed.
If the receiver of the ASP Up "agrees", then it responds
with ASP Up Ack.

In the Single Exchange model, this SINGLE positive exchange 
carries the same meaning for the state of both sides.  The 
initiator is saying "I want to move to the UP/Inactive state
and you can too". The [positive] responder is saying "you are 
now in the UP/Inactive state, and I am too".

So to answer your direct question, if both sides initiate
ASP Up messages around the same time, all is well, because
the two meanings coincide (both sides want to be UP/Inactive).  
To be successful, the ASP Up message requires an ASP Up Ack
message, so both sides respond to an ASP UP message with
an ASP UP Ack, and both sides move to the UP/Inactive state.

The same argument applies to ASP Active messages etc.

This Single Exchange Model requires that there be one Routing 
Key which fully specifies traffic in both directions.



Chris Benson, Software Engineer,
Adax Inc., Berkeley, California, USA.
    [email protected]
    +1 510 548-7047 ext. 189
    www.adax.com

On Mon, 15 Nov 2010, Jaddu, Suresh (NSN - IN/Bangalore) wrote:

>>  Date: Mon, 15 Nov 2010 23:10:01 +0800
>>  From: "Jaddu, Suresh (NSN - IN/Bangalore)" <[email protected]>
>>  To:  <[email protected]>
>>  Subject: [Sigtran] sending ASP UP in IPSP SE
>>  
>>  
>>  Hi All,
>>  
>>  I think this is very old discussion, I have searched through achieves
>>  but could not find definitive answer. In IPSP single exchange mode how
>>  to dentine that which side sends the ASP UP message during
>>  initialization. From the archives and also the RFC it looks like either
>>  side can initiate the M3UA messaging but in the absence of any
>>  predefined roles or any prior agreement how to know that which side
>>  sends the ASP UP.  In such situations it is certainly possible that both
>>  sides may send the ASP UP if that happens how to handle that, is it a
>>  valid case?? (if this is valid case then what is recommended handling).
>>  
>>  Thanks,
>>  SJ.
>>