Re: flow label demultiplexing

[Iljitsch van Beijnum <iljitsch@muada.com>]

On 19-apr-05, at 15:35, marcelo bagnulo braun wrote:

> > If we want to use the flow label for this we only need to change the 
> > flow label sematics every so slightly so the flow label is unique for 
> > a set of source/dest locators belonging to the same source and dest 
> > hosts rather than source/dest addresses. Not too unreasonable, IMO.

> Right, but i guess that what Pekka was pointing out is that, in the 
> case that the locator set are dynamic, you don't know when the locator 
> set will overlap in the future (because an locator that is already 
> present in one context is added to another one in the future), so it 
> is not possible to make sure that the flow id is not repeated in two 
> different contexts whose locator set overlap. Hence the problem.

Well, there are 1048575 possible flow label values so it's not 
necessary to reuse the same one for a new session all that quickly. The 
limitation is that the same flow label can't be used for a different 
session to the same shim-enabled destination host (regardless of 
address), for sessions to the same source/dest address pair for 
non-shim-enabled hosts and for sessions to ANY host where the 
shim-enabled status is unknown. Since presumably, we're going to find 
out whether a certain correspondent host is shim-enabled or not sooner 
rather than later, I don't see how this set of limitations can lead to 
trouble other than the general downside of adding some complexity.

Iljitsch