Subject: [Pana] Issue225: Cookie and stateless discovery

From: Yoshihiro Ohba <[email-masked]>
Date: Tue, 27 Dec 2005 11:57:44 -0500

>   A PANA-Start-Request message in stateless PAA discovery MUST NOT be
>   retransmitted as this voids the statelessness on the PAA.  Instead,
>   the PaC MUST retransmit the PANA-PAA-Discover message until it
>   receives a PANA-Start-Request message, and retransmit the
PANA-Start-
>   Answer message until it receives a PANA-Auth-Request message.  The
>   PaC can determine whether the PAA is using stateless PAA discovery
by
>   the presence of Cookie AVP. 
>
I may have missed it, but this is the first time I have seen presence of

the Cookie equating to stateless discovery. I don't see a MUST for the 
cookie if stateless discovery is being performed.

> The PANA-Start-Request message MUST be
>   retransmitted instead of the PANA-Start-Answer message when
stateless
>   PAA discovery is not used.
>
>   It is possible that both the PAA and the PaC initiate the discovery
>   and handshake procedure at the same time, i.e., the PAA sends a
PANA-
>   Start-Request message while the PaC sends a PANA-PAA-Discover
>   message.  To resolve the race condition, the PAA SHOULD silently
>   discard the PANA-PAA-Discover message received from the PaC after it
>   has sent a PANA-Start-Request message with creating a state (i.e.,
no
>   Cookie AVP is included in the message) for the PaC.  In this case
the
>   PAA will retransmit the PANA-Start-Request message based on a timer,
>   if the PaC doesn't respond in time (the message was lost for
>   example).  If the PAA had sent a PANA-Start-Request message without
>   creating a state for the PaC (i.e., a Cookie AVP was included in the
>   message), then it SHOULD answer to the PANA-PAA-Discover message.
>
>  
>
It seems to me that an explicit AVP, or even a different set of message 
types, for stateful vs. stateless would be more explicit, and be a lot 
easier to debug than piggybacking on the Cookie AVP to determine which 
mode you were operating in.

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