Subject: RE: [magma] Last Call: Source Address Selection for Multicast Listener Discovery Protocol (RFC 2710) to Proposed Standard (Fwd)

From: Erik Nordmark <[email-masked]>
Date: Mon, 14 Oct 2002 16:43:36 +0200 (CEST)

>----------------Begin Forwarded Message----------------<

Date: Mon, 14 Oct 2002 10:29:30 +0300
From: "Rami Lehtonen" <[email-masked]>
Subject: RE: [magma] Last Call: Source Address Selection for Multicast
Listener Discovery Protocol (RFC 2710 To: [email-masked]

Hi,

My comments regarding Source Address Selection for Multicast Listener
Discovery Protocol (RFC 2710):

You can now affect global multicast routing without even having a global
unicast address. I would like to see that for global multicast groups you
should "join" with global unicast address as source address.

Rami Lehtonen

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]On Behalf Of The
> IESG
> Sent: 11. lokakuuta 2002 23:07
> To: IETF-Announce:
> Cc: [email-masked]
> Subject: [magma] Last Call: Source Address Selection for Multicast
> Listener Discovery Protocol (RFC 2710) to Proposed Standard
>
>
>
> The IESG has received a request from the Multicast & Anycast Group
> Membership Working Group to consider Source Address Selection for
> Multicast Listener Discovery Protocol (RFC 2710)
> <draft-ietf-magma-mld-source-02.txt> as a Proposed Standard.
>
> The IESG plans to make a decision in the next few weeks, and solicits
> final comments on this action.  Please send any comments to the
> [email-masked] or [email-masked] mailing lists by 2002-10-25.
>
> Files can be obtained via
> http://www.ietf.org/internet-drafts/draft-ietf-magma-mld-source-02.txt
>
>
>
> _______________________________________________
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>----------------End Forwarded Message----------------<

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---

From: Erik Nordmark <[email-masked]>
Date: Mon, 14 Oct 2002 16:43:36 +0200 (CEST)

Hi,

Rami Lehtonen

---

From: Brian Haberman <[email-masked]>
Date: Mon, 14 Oct 2002 11:13:35 -0400

> should "join" with global unicast address as source address.

Let me try and state this another way.  Let me know if I have
misinterpreted.

The scope of the IPv6 source address must be equal to or greater than
the scope of the IPv6 multicast address being used.

Is that a correct assessment or are you only concerned with global
groups?

Given the fact that the plan for RFC 2710 is to keep it at PS and
not advance it to DS, what is the justification for putting this
restriction on MLDv1?  Wouldn't it be better to address this with
MLDv2/IGMPv3?

Is this restriction necessary for IGMPv3?  I would assume so since
IPv4 now has a flavor of link-local via the zeroconf work.  There
is no restiction there for joining global groups using a link-local
address.

I will also point out that the IGMPv3 spec mandates that a router
accept Report messages from 0.0.0.0.

Regards,
Brian

---

From: Brian Haberman <[email-masked]>
Date: Mon, 14 Oct 2002 11:13:35 -0400

Regards,
Brian

---

From: "Rolland Vida" <[email-masked]>
Date: Mon, 14 Oct 2002 17:36:00 +0200

Rami,

> > should "join" with global unicast address as source address.

We already talked about this subject with Brian. I imagine that your
question is related to the MCOP draft.

IMHO, using global addresses is not a good idea. First, it would break the
addressing hierarchy of IPv6. MLD messages have link-local use only, they
are not propagated beyond the link, a priori there is no reason to send them
with global addresses.

Saying that "MLD messages MUST be sent with global addresses" is not OK, as
nodes without global addresses would not be able to receive multicast.

Saying that "MLD messages MUST be sent EITHER with a valid link-local
address OR a global address" might introduce security flaws. The MLDv2 spec
avoids off-link forgery by requiring link-local source addresses for MLDv2
messages. Allowing global addresse would create a security problem.

Rolland

---

From: "Rolland Vida" <[email-masked]>
Date: Mon, 14 Oct 2002 17:36:00 +0200

Rami,

Rolland

---

From: Lehtonen Rami <[email-masked]>
Date: Tue, 15 Oct 2002 10:32:32 +0300 (EEST)

> question is related to the MCOP draft.

We can tackle the use of link locals in our specification (as Brian
instructed), so this it not related to MCOP.

> nodes without global addresses would not be able to receive multicast.

I'm not saying that MLD message MUST be sent with global address, but for
global groups receivers should use global address as source address (link
local is fine for other groups). This is similar behaviour than with
unicast, where the host use global address when communicating globally. Of
cource MLD has link-local use only, but it can affect multicast routing
globally.

> messages. Allowing global addresse would create a security problem.

You can handle off-link forgery with hop limit restrictions (verify to
contain 255). I don't see any additional security problem here.

If I'm the only one against this idea of using only link-local addresses
as source addresses for MLD messages, let's move on and move this to PS.

> Rolland

Rami

---

From: Lehtonen Rami <[email-masked]>
Date: Tue, 15 Oct 2002 10:32:32 +0300 (EEST)

Rami