Re: Flow label versus Extension header

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

El 24/04/2005, a las 19:52, Erik Nordmark escribió:
> > Second,  are you assuming that at this point the receiver know all 
> > the locator set of the initiator? are you assuming the the locator 
> > sets are static? Becuase if the locator sets are dynamic then i think 
> > that no one can be sure that the locator sets won't overlap in the 
> > future...
>
> You're probably assuming that the same tag is used in both directions.

i think i am not (but i am not sure :-)

I mean, do you think that if context tag values are repeated across 
different context, based on the fact that locator set of the peer are 
disjoint, receiver based context tag allocation can guarantee proper 
demux?

I mean, as i see it, when we are handling dynamic locator sets, the 
only option to guarantee proper demuxing is to solely rely in the 
context tag i.e. not include the addresses in the demux operation. 
Because if we inlcude the addresses in the demux, and we have repeated 
context tags, it always may occur that we end up with two contexts that 
have the same context tag (because we are using repeated context tags) 
and with the same locators (because they were added after we assigned 
the context tag, allowing to assign the same context tags initially, 
because initially the context tags were disjoints)

So, as i see it, the easier mechanisms to guarantee proper demux is to 
assign unique context tags and demux only based in context tags (not 
consider the addresses). Moreover, in order to guarantee this 
uniqueness, the simplest way is probably to use different context tags 
for each direction and to perform receiver based context tag 
allocation.
and finally because of the expected number of sessions, probably we 
need a bigger field than the flow label in order to guarantee 
uniqueness of the context tag.

I would say that this is the simpler approach. I may not be the most 
efficient though.

Regards, marcelo

>    Erik