Re: Comments on draft-bagnulo-multi6dt-hba-00.txt

On 19-nov-04, at 1:47, Erik Nordmark wrote:

> It's far from clear to me that, should we pursue router rewriting in 
> the future, that it can operate without being aware of individual 
> hosts addresses.

Maybe not, but there is also the possibility that it could work 
per-prefix but not per-host.

> For instance, if you have a site with 7 prefixes but some small 
> devices only choose to use 3 of them, and form HBA addresses using 
> those 3, then if the routers rewrite the source locator to any of the 
> other 4 prefixes then it might result in a complete failure to 
> communicate since the peer might ignore the "spoofed" packet coming 
> from an invalid source locator of the host.

I think it's possible to solve this. We've been talking about a bit 
that indicates (among other things) that rewriting is allowed. For a 
long time, I've been saying that we could use the prefix in the source 
address for this. So magic prefix = rewrite, regular prefix = don't 
rewrite. We can reserve some bits in the magic prefix that indicate the 
type of rewriting that's allowed. For instance, if the prefix is 
<iana:32><x:16><subnet:16><iid:64> then we can encode permission to 
rewrite to one or more of 16 different prefixes. There is the slight 
problem of having all systems involved know which prefix corresponds to 
which bit of course, but this should be doable.

On 19-nov-04, at 10:25, Brian E Carpenter wrote:

> It also seems to me that requiring the same IID for all interfaces is 
> architecturally wrong,

I certainly wouldn't want to require this, just allow it.