On 2008-03-29 16:01, Fred Baker wrote:
>
> On Mar 28, 2008, at 12:51 PM, Hemant Singh (shemant) wrote:
>
>> I think I am in general agreement of the consequences, but it isn't
>> about scope, it is about reachability. Anytime there is a a choice of
>> addresses to use, the same issue come to play. It's hard to know about
>> reachability with out prior knowledge or trying it out and seeing what
>> works. This applies to ULAs and other global scope unicast addresses,
>> IPv4 and IPv6 addresses, etc., etc.
>
> By this line of reasoning, scope is irrelevant. The only thing that the
> Robustness Principle would guide towards is the ability to exchange
> datagrams and open state with one's peer.
I think the problem is that scope, if you think of it as a set of
concentric circles of reachability, is a delusion.
Specifically,
On 2008-03-28 21:00, Fred Baker wrote:
> It should only send from a ULA if it knows that the peer has an address
> in the same prefix
Not so. The peer might, for example, have a prefix in
another private prefix, such as another ULA prefix, that
just happens to be reachable within the same enterprise
or via VPN. Expressing that reachability via a scope
suffix or by any kind of rule seems very hard. Treating
ULAs as global and relying on longest match to do the
right thing is probably the best we can do.
Brian
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