[mpls] Spencer Dawkins' No Objection on draft-ietf-mpls-oam-ipv6-rao-03: (with COMMENT)

["Spencer Dawkins" <[e-mail]>]

Spencer Dawkins has entered the following ballot position for
draft-ietf-mpls-oam-ipv6-rao-03: No Objection

When responding, please keep the subject line intact and reply to all
email addresses included in the To and CC lines. (Feel free to cut this
introductory paragraph, however.)


Please refer to http://www.ietf.org/iesg/statement/discuss-criteria.html
for more information about IESG DISCUSS and COMMENT positions.


The document, along with other ballot positions, can be found here:
http://datatracker.ietf.org/doc/draft-ietf-mpls-oam-ipv6-rao/



----------------------------------------------------------------------
COMMENT:
----------------------------------------------------------------------

Thanks for working with me to clear my Discuss, which was:

This Discuss ballot is probably more accurately a "Please clue in a TSV
AD who is trying to pattern match and failing" ballot, and likely quick
to resolve.

But, I'm looking at this text:

4.  Updates to RFC 4379

   [RFC4379] specifies the use of the Router Alert Option in the IP
   header.  Sections 4.3 and 4.5 of [RFC4379] are updated as follows:
   for every time in which the "Router Alert IP option" is used, the
   following text is appended:

      In case of an IPv4 header, the generic IPv4 Router Alert Option
      value 0x0 [RFC2113] SHOULD be used.  In case of an IPv6 header,
                          ^^^^^^
      the IPv6 Router Alert Option value TBD1 allocated through this
      document for MPLS OAM MUST be used.
      
When I click over to Section 4.3 of [RFC4379], I see this text:

4.3.  Sending an MPLS Echo Request

   An MPLS echo request is a UDP packet.  The IP header is set as
   follows: the source IP address is a routable address of the sender;
   the destination IP address is a (randomly chosen) IPv4 address from
   the range 127/8 or IPv6 address from the range
   0:0:0:0:0:FFFF:127/104.  The IP TTL is set to 1.  The source UDP port
   is chosen by the sender; the destination UDP port is set to 3503
   (assigned by IANA for MPLS echo requests).  The Router Alert option
   MUST be set in the IP header.
   ^^^^
   
Could you help me understand whether this is really a MUST in Section 4.3
of [RFC4379] that is morphing into a SHOULD for IPv4 and remaining a MUST
in IPv6?

I have the same confusion in Section 4.5, but I'm betting the same answer
applies.