Re: multi6-functional-dec and re-homing

[marcelo bagnulo braun <marcelo@it.uc3m.es>]

El 19/01/2005, a las 13:04, <john.loughney@nokia.com> escribió:

> Marcelo,
>
> > well, i am not sure about this...
> > My point was about establishing new communication after an outage with
> > external hosts that don't implement the shim.
> > This is important becuase at least in the early days, most of nodes
> > won't implement shim.
> > Explicitly taking this point into consideration would allow to provide
> > some degree of fault tolerance (i.e. the capability of establishing 
> > new
> > communications after an outage) even in communications with nodes that
> > don't implement the shim.
>
> This is a general transition issue; I guess the protocol should 
> specify how
> an shim6 endpoint works with a non-shim6 endpoint.

I don't know...
I mean, on one hand, you are right, the shim protocol must specify how 
to deal with non-shim hosts. this means essentially the capability 
detection functions of the functional dec draft.
However, there is more that can be done in this context i suppose. I 
mean there are some fault tolerance capabilities that can be provided 
even though the communication is established with a non shim host. In 
particular, it is possible to establish new communications after an 
outage if the host withn the multihomed site is able to smartly select 
the source address to be used for that communication. In order to do 
this, the multihomed host needs modifications in the source address 
selection mechanism.
Such mechanism could also be used when establishing communications with 
a shim node, but perhaps in this scenario superior solutions can be 
obtained since both nodes implement the mechanism.
So, i guess that my point is that when a non shim node is involved in a 
communication, it would be good if we did more that just  detecting 
that the shim is not supported, but we could deploy mechanisms to 
provide enhanced fault tolerance in this scenario.

(It could also be noted that such mechanism is likely to be much 
simpler than the whole shim and that it will, by itself, provide some 
degree of fault tolerance, so it may make sense to deploy it even 
without the shim)

Makes sense?

regards, marcelo




> John