[Tinyos-host-mote-wg] Discussion

[Ben Greenstein]

On Apr 12, 2005 12:30 PM, David Gay <david.e.gay at intel.com> wrote:
> Ben Greenstein wrote:
> > On Apr 11, 2005 5:30 PM, Philip Levis <pal at cs.berkeley.edu> wrote:
> >>On the notion of connection-based versus connectionless protocols. The
> >>distinction lies in how much state you can assume the other side
> >>maintains. In a connectionless protocol, you need to include additional
> >>state in every packet, state which in a connection-oriented protocol
> >>would be maintained as part of the connection.
> >
> > Yes. Another way to look at this problem is identify what information
> > each device needs to know about its peer:
> > - whether or not the peer is alive
> > - sequence numbers for sliding window reliability over serial
> > - device characterizations (e.g., micaz or mica2)
> > - protocol characterizations (e.g. no compressed headers)
> > Given these requirements, I am wholeheartedly in favor making the
> > datalink layer (the sum of hdlc and ppp) connection-oriented.
> 
> Your list is not very strong support for that, though:
> - peer alive: connection-oriented doesn't help

point taken... we need something stronger than connection-orientation
for this.... like persistent and perpetual connection reaffirmation :)

> - protocol characteristics: this is an artifact of using ppp

but might be an artifact of using another protocol with options as well

> 
> So that only leaves
> - device characteristics: at most a couple of bytes
> - reliability: I think the connection is actually providing a known
> starting point (e.g., after the open, I know the window is fully
> available - without the known starting point you would have a potential
> race when receiving a message indicating N window slots available just
> after sending a message), not really saving space (this is in slight
> contradiction to Phil's point of course ;-))
> 
> David
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