Subject: [MBONED] IPv6 node requirements: multicast

From: Pekka Savola <[email-masked]>
Date: Mon, 21 Feb 2011 08:10:54 +0200 (EET)

Heads-up,

6man WG ([email-masked]) is at a WGLC phase of an informational 
document revising IPv6 node requirements:

http://tools.ietf.org/html/draft-ietf-6man-node-req-bis-07

Current text on multicast is in S 5.9 (essentially a MUST for MLDv1, 
a conditional SHOULD for MLDv2) and for routers in S 12.1.1.

I've pointed out that the lightweight MLDv2 implementation spec should 
probably be added as a MAY.

Now would probably be a good time to comment on the document on 6man 
WG list.

5.9. Multicast Listener Discovery (MLD) for IPv6 - RFC 2710

    Nodes that need to join multicast groups MUST support MLDv1
    [RFC2710].  MLDv1 is needed by any node that is expected to receive
    and process multicast traffic.  Note that Neighbor Discovery (as used
    on most link types -- see Section 5.2) depends on multicast and
    requires that nodes join Solicited Node multicast addresses.

    Nodes that need to join multicast groups SHOULD also implement MLDv2
    [RFC3810].  Specifically, if the node has applications that need
    support for Source-Specific Multicast [RFC3569], the node MUST
    support MLDv2 as defined in [RFC3810], [RFC4604] and [RFC4607].  If
    the node only supports applications that use Any-Source Multicast
    (i.e, they do not use source-specific multicast), implementing MLDv1
    [RFC2710] is sufficient.  In all cases, nodes are strongly encouraged
    to implement MLDv2 rather than MLDv1, as the presence of a single
    MLDv1 participant on a link requires that all other nodes on the link
    operate in version 1 compatibility mode.

    When MLDv1 is used, the rules in the Source Address Selection for the
    Multicast Listener Discovery (MLD) Protocol [RFC3590] MUST be
    followed.

12.1.1. IPv6 Router Alert Option - RFC 2711

    The IPv6 Router Alert Option [RFC2711] is an optional IPv6 Hop-by-Hop
    Header that is used in conjunction with some protocols (e.g., RSVP
    [RFC2205] or MLD [RFC2710]).  The Router Alert option will need to be
    implemented whenever protocols that mandate its usage (e.g., MLD) are
    implemented.  See Section 5.9.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

---

From: Hitoshi Asaeda <[email-masked]>
Date: Mon, 21 Feb 2011 16:35:34 +0800 (HKT)

> Current text on multicast is in S 5.9 (essentially a MUST for MLDv1, a
> conditional SHOULD for MLDv2) and for routers in S 12.1.1.
> 

Thanks, Pekka.

IMO, "if the node has applications that need support for
Source-Specific Multicast, the node MUST support either MLDv2 or
LW-MLDv2", would be better. Anyway, I'll comment it to 6man ML.

Thank you.
Regards,
--
Hitoshi Asaeda

---

From: Hiroaki Sato <[email-masked]>
Date: Wed, 23 Feb 2011 09:39:04 +0900

Hi all,

I agree with Hitoshi.
And I don't think MLDv1 "MUST" supports when MLDv2 or LW-MLDv2(in SSM 
case) is supported.
Although IGMPv2 is popular, is MLDv1 so?

Thank you,
Hiroaki

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