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Re: Flow label versus Extension header - protocol itself

On 2-mei-2005, at 11:53, Francis Dupont wrote:

=> basically as there is no way to deal with a new extension header
without
modifying code or more, this will kill all the boxes which are looking
inside packets for good or less good reasons. 

   I don't think that in this stadium of IPv6 deployment this is that
   huge a deal.

=> I am sorry but I believe to propose major changes in IPv6 is no more
a good idea today. Perhaps you have a little deployment where you are
but don't expect it is the case everywhere...

So basically what you're saying is that we need to have a moratorium on new extension headers just because SOME hard/software used by SOME people may not support it.

Since in this case the only problem that they have is that they won't be able to use the new feature (shim6 multihoming) I don't see why this should be a problem at all. Either upgrade or be single homed. And since only a tiny percentage of all users has IPv6 in the first place and a tiny percentage of those users has a firewall, I really fail to see the problem.

   pretty clear that using the flow label for demux can be
   done without impact to other flow label use, at the cost of some
   extra complexity when selecting the flow label for a new session.


=> but the flow label selection is already an essential part of
RFC 3697.

So? How does what we're proposing to do with the flow label break RFC 3697?

PS: I still believe the best is a destination option.

The trouble with a destination option is that you need to spend 8 bytes so you get a 4 byte payload, and the possibility of having multiple destination options that need to be in different places in the protocol chain is just asking for nasty bugs. Also, we need two other mechanisms (reachability detection and capability/security negotiation) that aren't naturally suited to being destination options but could very well live in the same extension header as a demux option.