Source Address Selection for the Multicast Listener Discovery (MLD) Protocol (RFC3590)
Original Publication Date: 2003-Sep-01
Included in the Prior Art Database: 2003-Sep-09
Internet Society Requests For Comment (RFCs)
It has come to light that there is an issue with the selection of a suitable IPv6 source address for Multicast Listener Discovery (MLD) messages when a node is performing stateless address autoconfiguration. This document is intended to clarify the rules on selecting an IPv6 address to use for MLD messages.
Network Working Group B. Haberman
Request for Comments: 3590 Caspian Networks
Updates: 2710 September 2003
Category: Standards Track
Source Address Selection for the
Multicast Listener Discovery (MLD) Protocol
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (2003). All Rights Reserved.
It has come to light that there is an issue with the selection of a
suitable IPv6 source address for Multicast Listener Discovery (MLD)
messages when a node is performing stateless address
autoconfiguration. This document is intended to clarify the rules on
selecting an IPv6 address to use for MLD messages.
The original specification of the Multicast Listener Discovery
Protocol (MLD) for IPv6 [RFC 2710] mandates the use of a link-local
IPv6 source address for the transmission of MLD messages. In
addition, MLD also requires nodes to send MLD Report messages when
joining any IPv6 multicast group (except the All-Nodes address and
addresses of scope less than 2).
These MLD requirements conflict with the use of IPv6 multicast within
the Neighbor Discovery Protocol [RFC 2461]. For stateless
autoconfiguration, as defined in [RFC 2462], a node is required to
join several IPv6 multicast groups in order to perform Duplicate
Address Detection prior to its use. Since the only address the node
has is tentative, and cannot be used for communication, it does not
have a suitable address to utilize as a source address.
Haberman Standards Track [Page 1]
RFC 3590 Source Address Selection for MLD Protocol September 2003
This document will clarify the IPv6 source address selection rules
for use with MLD when no link-local addresses are available.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC 2119].
In [RFC 2710], Section 3 requires that all MLD messages be sent with
a valid link-local IPv6 source address. However, a node in the
process of performing duplicate address detection for its link-local
(LL) address will not have one available to use as a source address.
For this reason, this document allows the unspecified address to be
used as a source address for MLD messages being used during duplicate
The discrepancies in the rules defined in [RFC 2710] and [RFC 2462]
has led to implementation issues. Several IPv6 implementations skip
sending MLD Report messages during duplicate address detection
because they have no valid link-local address. This leads to
operational problems when a node is attached to switches that...