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Last Call Review of draft-ietf-bier-tether-04

Request Review of draft-ietf-bier-tether
Requested revision No specific revision (document currently at 05)
Type Last Call Review
Team General Area Review Team (Gen-ART) (genart)
Deadline 2024-02-29
Requested 2024-02-15
Authors Zhaohui (Jeffrey) Zhang , Nils Warnke , IJsbrand Wijnands , Daniel O. Awduche
I-D last updated 2024-02-15
Completed reviews Rtgdir Telechat review of -05 by Adrian Farrel
Secdir Last Call review of -05 by Wes Hardaker
Opsdir Last Call review of -05 by Dan Romascanu
Genart Last Call review of -04 by Joel M. Halpern (diff)
Assignment Reviewer Joel M. Halpern
State Completed
Request Last Call review on draft-ietf-bier-tether by General Area Review Team (Gen-ART) Assigned
Posted at
Reviewed revision 04 (document currently at 05)
Result Ready w/issues
Completed 2024-02-15
I am the assigned Gen-ART reviewer for this draft. The General Area
Review Team (Gen-ART) reviews all IETF documents being processed
by the IESG for the IETF Chair.  Please treat these comments just
like any other last call comments.

For more information, please see the FAQ at


Document: draft-ietf-bier-tether-04
Reviewer: Joel Halpern
Review Date: 2024-02-15
IETF LC End Date: 2024-02-29
IESG Telechat date: Not scheduled for a telechat

Summary: This document is almost ready for publication as a proposed standard

Major issues:
    Section 3.1 on IGP Signaling states "The helper node (BFRx) MUST advertise
    one or more BIER Helped Node sub-sub-TLVs".  However, I only find a vague
    outline of this sub-sub TLV.  The code point for it is requested in the
    IANA considerations section, but the description is a single sentence
    easily misread and lacking the conventional diagrams and precision that is
    used to define routing TLVs (and sub or sub-sub TLVs.)

Minor issues:
    In the paragraph about multiple helpers helping a single non-supporting
    router, I think I missed how one case works properly.  (Section 2,
    additional considerations, paragraph 6).  The text says that the sending
    BFR (BFR1 can choose to use multiple helpers if they are available. 
    Assuming that BFR1 chooses to use BFR2 and BFR 3 to reach BFRs 4 .. BFR N,
    the text is clear that this results in BFR2 and BFR 3 both sending copies
    of the packet to Router X.  That is fine.  It is load, but it is a
    tradeoff.  However, it appears that both BFR2 and BFR 3 would send packets
    to BFR4, and to all the other BFR children of X.  This results in duplicate
    packets in the rest of the tree.  Is there some assumption I missed that
    prevents this?

Nits/editorial comments: