Designing IPv6 network guidelines?

[horape@tinuviel.compendium.net.ar]

¡Hola!

> > >1) Some RFC recommended using site-local addresses for point to point
> > >links.  Won't this break traceroute?
> >
> > 	you don't even need site-locals for point to point links.  they just
> > 	work fine with link-local address.  all routing protocols should run
> > 	fine with p2p with link-local address only.
> 
> Also, why _would_ traceroute work?  If the link local address of a P-t-P
> link were to use private addresses, you couldn't trace through the
> internet.

I was thinking the same thing and did some tests. If the routers have only
link-local addresses traceroute breaks, but if they have any global address
(in other interface) it uses that address.

Further investigation has led me to the following:

RFC2463 (ICMPv6) says:

    (c) If the message is a response to a message sent to an address
        that does not belong to the node, the Source Address should be
        that unicast address belonging to the node that will be most
        helpful in diagnosing the error. For example, if the message is
        a response to a packet forwarding action that cannot complete
        successfully, the Source Address should be a unicast address
        belonging to the interface on which the packet forwarding
        failed.

Being that that interface has not a helpful address, it avoids the "should
be a unicast address belonging to the interface..." and uses "a unicast
address belonging to the gateway". (Spelling OT: is correct "a unicast" 
or should it be "an unicast" ?)

RFC1812 (Requirements for IP Version 4 Routers) talks in section 2.2.7
about "Unnumbered Lines and Networks Prefixes" and decides:

   Because of these drawbacks, this memo has adopted an alternate
   scheme, which has been invented multiple times but which is probably
   originally attributable to Phil Karn.  In this scheme, a router that
   has unnumbered point to point lines also has a special IP address,
   called a router-id in this memo.  The router-id is one of the
   router's IP addresses (a router is required to have at least one IP
   address).  This router-id is used as if it is the IP address of all
   unnumbered interfaces.

Adapting it to IPv6 you'd talk about p2p using link-local addresses, and
requiring any router to have at least one global IP address.

> 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

					HoraPe
---
Horacio J. Peña
horape@compendium.com.ar
horape@uninet.edu
bofh@puntoar.net.ar
horape@hcdn.gov.ar