On Tue, 23 Apr 2002, JINMEI Tatuya / [ISO-2022-JP] 神明達哉 wrote:
> > For regular packet forwarding, the second bullet in 9. basically seems to 
> > say: "if you cross the zone boundary, the packet is discarded".
> 
> This is oversimplification.  The second ballet says "a packet must not
> cross the zone boundary of the source address's zone".

Ok.
 
> > This should be, IMO, honoured with routing header too.
> 
> As for the source address, that's correct (or at least what the draft
> intended to say).

Routers N hops away may have difficulties in determining this with a 
certainty.
 
> > In particular, one 
> > should not be able (IMO) to control how routing should go inside a site, 
> > using site-internal addresses (as these addresses aren't reachable to the 
> > source, and may have a different level of security etc.).  If the 
> > destination site does not have global addresses in use there, he probably 
> > don't want site-local's being used either.
> 
> Sorry, I don't understand the statement above.  Could you be more
> specific please?

AFAICS, the following is allowed:

Assume sites A and B.

src=globalA
dst=globalB
routing header=sitelocalB, global2B
segments left=2

So source A is able to control how globalB inserts a packet from a global 
source to site _B_'s internal, site-local routing system.  You could of 
course also, after using the routing system, revert the destination back 
to some global one.

My point here was: anyone from site A should not be able tell how site B 
should route packets using _site-local_ addresses?
 
> > Site-locals are potentially fishier as they can't be as trivially
> > restricted to a link.
> 
> > I'd like to see a "roadmap" of what kind of forwarding is possible with
> > routing header, and what is not.  I couldn't make a clear mental image
> > based on the text.
> 
> I'm not sure what "roadmap" exactly means, but the restriction that
> Rich mentioned will be clearer about the rule...

I'd like to know what people vision RH + scoping would be useful for.

Then it might be easier to decide whether a simpler approach would be 
appropriate.
 
> > That is, can you use RH to forward packets out of the incoming link with
> > e.g. link-local addresses?  (As in the previous paragraph in the text.)
> 
> That depends on the precise configuration, as I said above.

I'm not sure if that's obvious from the text.

> p.s. to make my position clear, I'm not a fan of the current rule.
> Formerly I proposed a stricter rule that required all destinations in
> a routing header were in the same scope type for deterministic
> behavior.  

I tend to agree.

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords


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