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Early Review of draft-ietf-pim-rfc1112bis-07
review-ietf-pim-rfc1112bis-07-iotdir-early-nordmark-2026-01-27-00

Request Review of draft-ietf-pim-rfc1112bis
Requested revision No specific revision (document currently at 08)
Type Early Review
Team Internet of Things Directorate (iotdir)
Deadline 2026-02-04
Requested 2026-01-20
Requested by Stig Venaas
Authors Toerless Eckert , Dr. Steve E. Deering
I-D last updated 2026-02-26 (Latest revision 2026-02-26)
Completed reviews Rtgdir Early review of -07 by Zheng Zhang (diff)
Intdir Early review of -07 by Pascal Thubert (diff)
Iotdir Early review of -07 by Erik Nordmark (diff)
Secdir Early review of -07 by Brian Weis (diff)
Comments
If possible, it would be good to get some of these reviewers.
 
SECDIR: Brian Weis, Kyle Rose, Dave Thaler
TSVDIR: Michael Tüxen, Kyle Rose
INTDIR: Jen Linkova, Rick Taylor, Pascal Thubert, Michael Tüxen, Dave Thaler
IOTDIR: Pascal Thubert, Eric Nordmark, Carsten Borman

Note that Brian Haberman has done extensive reviews of this document, so it is best to not have him as a reviewer.
Assignment Reviewer Erik Nordmark
State Completed
Request Early review on draft-ietf-pim-rfc1112bis by Internet of Things Directorate Assigned
Posted at https://mailarchive.ietf.org/arch/msg/iot-directorate/_0-OQaHy02U84BNoVD0UL7as0x8
Reviewed revision 07 (document currently at 08)
Result Ready w/issues
Completed 2026-01-27
review-ietf-pim-rfc1112bis-07-iotdir-early-nordmark-2026-01-27-00
I have a question around Level 2L, which is new to me. In the past there has
been an assumption that layer 2 devices (bridges, L2 switches) can perform
IGMP/MLD snooping to determine what to filter based on Ethernet multicast
addresses. Back in the day this possible except that the all-hosts (IPv4) and
all-nodes (IPv6) would always need to be forwarded at L2. Has the industry
moved away from IGMP/MLD snooping? And is the draft trying to say that an
implementation is free to implement support for IGMP/MLD snooping but it is not
part of the standard? (The intent of the different sections are not quite clear
to me on this topic.)

Security considerations: have there been any discussion about the fact that
applications should not assume that traffic sent to a link-local multicast
address was sent by a host on the attached link? (various tunneling approaches
can be used to have a router potentially send such a packet on a link.) Is this
worth noting?

Terminology nit:
For better or worse, the IPv6 RFCs do not use the term "IPv6 host group", yet
in this document that term appears three times. Some of those are odd - "IPv6
host group address" should be replaced by "IPv6 multicast address". The one in
section 4 might make sense to keep (but reword) to make the connection with the
IPv4 terminology. Thus I'd suggest changing "IPv6 Host groups are identified by
IPv6 addresses" to "In IPv6 the concept of host groups are identified by IPv6
multicast addresses" or something along those lines.

Section 9.2:
I'm having a hard time parsing this sentence "do or may include backward
compatibility with IGMPv1" since it isn't clear what "do or may" means when
referring to existing specifications. Is this intended to refer to
implementations?

Section 10.8 typo: "MLS" should be "MLD".

Section 12.2 says "keep an IP multicast address secret"
That can easily be read as "secure" when "obscure" would be a better name for
it. This is an observation about the pssibility to have randomly generated IPv6
multicast addresses, and if such are used, it is hard (but not impossible) to
find them by trial and error. But many IPv6 protocols use well-defined fixed
multicast addresses.