Subject: Re: Unnumbered and tunnel interfaces in OSPFv3

From: Nic Neate <[email-masked]>
Date: Mon, 6 Sep 2004 15:20:55 +0100

Hi Acee,

Thanks for your response.  I agree that the Link-LSA doesn't seem to have a
purpose on unnumbered links, and perhaps an option not to use the Link-LSA
on any P2P links would also be appropriate.

To tie things down, I think we agree that OSPFv3 should run over unnumbered
interfaces as follows.  Please let me know if there is anything missing or
incorrect.

 - For OSPFv3 purposes, an unnumbered interface is defined as an interface
with no link-local address (but possibly with site-local or global
addresses).

 - Any address on the corresponding node is used for the source/destination
address in protocol packets sent over unnumbered interfaces (as in OSPFv2).

 - Unnumbered interfaces are identified in the protocol (for example, in
Router-LSAs) by their Interface ID and Router ID (as with numbered
interfaces).

 - The Link-LSA is not sent over unnumbered interfaces.  Any site-local or
global addresses configured are advertised in the router's
Intra-area-prefix-LSA.

Do you think there would be scope/demand for a short draft to standardize
this?  I would be happy to contribute if so.

Thanks,

Nic

-----Original Message-----
From: Acee Lindem [mailto:[email-masked]]
Sent: Thursday, September 02, 2004 10:26 PM
To: [email-masked]
Subject: Re: Unnumbered and tunnel interfaces in OSPFv3

Hi Nic,

----- Original Message -----
From: "Nic Neate" <[email-masked]>
To: <[email-masked]>
Sent: Thursday, September 02, 2004 10:55 AM
Subject: Unnumbered and tunnel interfaces in OSPFv3

> Hi all,
>
> I have a few OSPFv3 questions I was hoping someone could help me with.
>
> 1.  Is there any concept of an unnumbered interface in OSPFv3?  (As far as
I
> can see from RFC 2740, there isn't.)

Since OSPFv3 runs on a link rather than a subnet, there should be fewer
considerations.

>
> 2.  If yes, how do they work?  I would guess most principles from OSPFv2
can
> be carried over, but what about usage of the Link-LSA?

It seems that it could be suppressed for unnumbered LSAs. In fact, it has
crossed
my mind that they could be suppressed for all OSPFv3 P2P links. At least in
our
implementation, we don't need to discover the link local address and any
prefixes
associated with the link are advertised in one of the router
intra-area-prefix LSAs.

>
> 3.  If not, are there any guidelines on how, for example, RSVP tunnel
> interfaces should be handled?

I would think this would be transparent to OSPFv3.

> Thanks in advance,
> Nic

---

From: Acee Lindem <[email-masked]>
Date: Tue, 7 Sep 2004 07:34:53 -0400

Hi Nic,

----- Original Message -----
From: "Nic Neate" <[email-masked]>
To: <[email-masked]>
Sent: Monday, September 06, 2004 10:20 AM
Subject: Re: Unnumbered and tunnel interfaces in OSPFv3

> with no link-local address (but possibly with site-local or global

It funny but I would have interpreted it to be just the opposite - an interface
with a link-local address of one sort or another and no site-local or global
addresses.

> address in protocol packets sent over unnumbered interfaces (as in OSPFv2).

I don't agree here since I think there still should be a link-local address.

> Router-LSAs) by their Interface ID and Router ID (as with numbered

Agreed.

> global addresses configured are advertised in the router's

I don't think the Link-LSA is required on P2P links - see below.

> this?  I would be happy to contribute if so.

In thinking about this more, I think an "unnumbered" link in IPv6 is simply
any interface that has a link-local address but no global addresses (note
that site-local addresses have been deprecated). Hence, this is already
handled by RFC 2740. We may want to have more discussion of allowing
link-LSAs to be omitted on P2P links.