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Re: flow label demultiplexing




El 19/04/2005, a las 15:00, Iljitsch van Beijnum escribió:

On 19-apr-05, at 14:51, marcelo bagnulo braun wrote:

Under what circumstances would having different associations between the same source and destination locator sets be necessary and/or useful?

Well, i think they may occur pretty naturally, and that we probably need to do something in order to avoid it from happening. Correct me if i wrong in the next scenario:

Node A has IPA1 and IPA2
Node B has IPB

Two communications are initiated between the nodes. Because no address is preselected, one of the communications is using IPA1 and IPB as ULIDs and the other one is using IPA2 and IPB as ULIDs. Now an outage occurs affecting IPA1 and the communication involving IPA1 and IPB is moved to the alternative locator i.e. IPA2.

At this point, packets corresponding to any of the communications contain the same addresses, IPA2 and IPB, and they need to be demultiplexed.

Yes, this is a good example. So:

- demultiplexing packets to the right association can very likely be done based on the address pair, but
- demultiplexing packets to the right ULIDs can't be done on addresses alone, either this must be done based on higher layer information, the flow label or something new


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.


Regards, marcelo