same link-local address on multiple interface and OSPFv3

[Matjaž Straus Istenič]

A short wrap-up:

On 29. jun. 2013, at 22:31, Brian E Carpenter <brian.e.carpenter at gmail.com> wrote:

> On 29/06/2013 22:18, Benedikt Stockebrand wrote:
>> Hi Phil and list,
>> 
>>> [Using the same link-local address on multiple (VLAN) interfaces]
>>> 
>>> Many routers wouldn't let you do that in IPv4. Cisco IOS doesn't, for
>>> example:
>> 
>> IPv4 doesn't have link-local addresses or anything similar (unless you
>> want to consider 192.169/16 "similar" in this context).
> 
> Of course not, but I was trying to see how deep in the product
> design the issue might go. It sounds like dumb copying of the IPv4
> logic (where as Gert says there is no implied scope and therefore
> a real ambiguity).

In this particular case the logic that signals that the local OSPF-interface is not ready was copied from IPv4 OSPF to OSPFv3. I've run with a simple test.

- Configured two IRB (or BVI or Vlan X, you name it) interfaces or router R1, bot with the same IPv6 link-local address (fe80::10:1:1:1) and no global addresses.
- I run OSPFv3 on one of them, the other is just sitting there, like this:

      tcpdump here
      |
      v
+----+*fe80::10:1:1:1---OSPF------*+----+
| R1 |                             | R2 |
+----+*fe80::10:1:1:1---no-OSPF---*+----+
                                  ^
                                  |
                                  shutdown this interface

- OSPFv3 adjacency come up and everything is fine.
- Then I drop the non-OSPF link by shutting down the interface on the neighboring side R2.

- From the tcpdump at R1 I can see that R1 stops sending OSPF hello messages.
  R1 says: ipv6 src Address fe80::10:1:1:1 is not ready
  ...and stops sending OSPF helloes.

- OSPF at R1 gets stuck in the Init state.

> 
>    Brian

Thank you all for all your comments and feedback.
Kind regards,

	Matjaž