Éric Vyncke's Discuss on draft-ietf-bfd-vxlan-09: (with DISCUSS and COMMENT)

Éric Vyncke via Datatracker <noreply@ietf.org> Tue, 17 December 2019 08:51 UTC

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Éric Vyncke has entered the following ballot position for
draft-ietf-bfd-vxlan-09: Discuss

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Thank you for the work put into this document.

I fully second Adam's COMMENT that should be fixed before publication (IMHO
this is a DISCUSS).

Answers to my COMMENTs below will be welcome, even if those COMMENTs are not

As usual, an answer to the DISCUSS is required to clear my DISCUSS though.

I hope that this helps to improve the document,




May be I am not familiar enough with BFD, but, RFC 5881 (the one defining BFD)
specifies the use of TTL = Hop Limit = 255.. Why this document uses a value of
1 ?

-- Section 3 --
IPv4-mapped IPv6 addresses are only to be used inside a host and should never
be transmitted in real packets (including packets inside a tunnel) see section
4.2 of RFC 4038 (even if informational). As other IESG reviewers, I wonder why
::1/128 is not used?

-- Section 8 --
The document specifies no IANA actions while the shepherd write-up talks about
a IANA action.

-- Section 9 --
This section is only about IPv4 (TTL and RFC 1812). Please address IPv6 as well.



RFC 5881 (BFD) states that it applies to IPv4/IPv6 tunnels, may I infer that
this document is only required to address the Ethernet encapsulation ? I.e.
specifying the Ethernet MAC addresses?

-- Section 3 --
At first sight, I was surprized by having a BFD session per VXLAN VNI as it
will create some scalability issue, but, I assume that this is to detect
misconfiguration as well. If so, perhaps worth mentionnig the reasoning behind?

In "the inner destination IP address SHOULD" it is unclear whether it is in the
all BFD packets, or only the request one or ... ?

-- Section 4 --
While probably defined in RFC7348, should "FCS" be renamed as "Outer Ethernet
FCS" for consistency with the "Outer Ethernet Header" in figure 2 ?

Why not using the Source MAC address as the Destination MAC address ? This
would ensure that there is no conflict at the expense of "forcing" the
transmission of the frame even if addressed to itself.

Please consider rewriting the section about TTL/Hop Limit as it is not easy to

-- Section 9 --
It is unclear to me (see also Ben's comment) what is the 'attack vector' of
sending packets with TTL=1 ?