On Tue, Apr 24, 2007 at 02:53:39AM +0300, Alper Yegin wrote:
> > > PANA-Ping-Request/Answer could have a separate state machine. That way,
> > the
> > > transitions in that state machine does not interfere with transitions in
> > the
> > > other state machine that deals with processing any other PANA message.
> > 
> > I believe having a separate state machine for ping works only when
> > ping has a separate sequence number space, otherwise, there would be
> > no way to avoid interference between the two state machines (ping
> > state machine and state machine for other messages).  But I may be
> > missing something.
> 
> Do the sequence numbers play a role our state machines? I hadn't thought so.

The play is implicit based on the following lock-step constrations:

- Each peer maintains a single sequence number space for outgoing
requests.

- There is only one outstanding outgoing request allowed for each
peer.  A peer that receives a request accepts the sequence number
which is last received sequence number + 1 only.

This means sequence numbers play a role in our state machine.  Running
multiple state machines in pararell and independenly would break the
lock-step constraints.

Yoshihiro Ohba



> 
> Alper
> 
> 
> 
> 
> > 
> > Yoshihiro Ohba
> > 
> > 
> > >
> > > This scheme prevents any special case handling to be part of the
> > protocol
> > > specification.
> > >
> > > Your suggestion below works too I believe. Though I lean towards the
> > above
> > > suggestion, given that it does not special case one type of message in
> > the
> > > spec.
> > >
> > > I remember once mentioning use of a separate state machine for pings. I
> > > don't remember what the feedback was....
> > >
> > > Alper
> > >
> > >
> > > > which will end up with the 2*N
> > > > problem.  On the other hand, it may be possible for the PaC to queue
> > > > the incoming PAR until the ping request is answered.
> > > >
> > > > So how about relaxing the third item to:
> > > >
> > > > "
> > > > - When there is an outstanding ping request, all incoming messages
> > > >   MUST NOT be processed except for ping answer or error request sent
> > > >   in response to the ping request.
> > > > "
> > > >
> > > > Yoshihiro Ohba
> > > >
> > > > >
> > > > > Alper
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >
> > > > > > This may be an acceptable operation.
> > > > > >
> > > > > > Yoshihiro Ohba
> > > > > >
> > > > > >
> > > > > > >
> > > > > > > Alper
> > > > > > >
> > > > > > >
> > > > > > >
> > > > >
> > > > >
> > > > > _______________________________________________
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> > > > > [email protected]
> > > > > https://www1.ietf.org/mailman/listinfo/pana
> > > > >
> > >
> > >
> 
> 

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