Subject: [Last-Call] Genart telechat review of draft-ietf-bfd-vxlan-09

From: Erik Kline via Datatracker <[email-masked]>
Date: Mon, 16 Dec 2019 21:19:56 -0800

Reviewer: Erik Kline
Review result: Ready with Nits

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Document: draft-ietf-bfd-vxlan-??
Reviewer: Erik Kline
Review Date: 2019-12-16
IETF LC End Date: None
IESG Telechat date: 2019-12-19

Summary:

-09 addresses my concerns from -07.  Thank you for this.

The one "nit" is that it seems to have introduced a recommendation to use
::ffff:7f00:0/104 as an IPv6 loopback prefix.  (a) This document should follow
the format recommendations of RFC 5952 section 4.3 and lowercase the "F"s.  But
(b) more importantly, I'm not sure how implementations may treats this space.

The use of an RFC4291 section-2.5.5.2 mapped v4 address doesn't necessarily
make the packet a part of an IPv6 connection.  Nevertheless, I'm not sure I
have a strong feeling about this as it may still exercise enough of the IPv6
stack in a VTEP.

I definitely do think that in the case of BFD on the management VNI targeting
an IPv6 link-local address of the VTEP would be better.  However, I expect that
if ::ffff:127.0.0.0 does prove to have some issues in the future a -bis can be
written quickly with a recommendation.

Also, Suresh may have ideas for a solution.

Major issues:

Minor issues:

Nits/editorial comments:

---

From: Greg Mirsky <[email-masked]>
Date: Tue, 17 Dec 2019 15:17:21 -0800

Hi Erik,
thank you for your reviews and for sharing thoughts on the selection of the
destination IPv6 address. Following recommendations from Adam, I've updated
the document to use the proper representation of IPv6 addresses and refer
to them as "IPv4-mapped IPv4 loopback addresses". These updates are in the
attached diff. Adam also noted that RFC 8504 doesn't have a similar wording
regarding the handling of packets addressed to an address from 127/8
network as RFC 1812 (of course, referring to IPv4-mapped 127/8 addresses):
      A router SHOULD NOT forward, except over a loopback interface, any
      packet that has a destination address on network 127.  A router
      MAY have a switch that allows the network manager to disable these
      checks.  If such a switch is provided, it MUST default to
      performing the checks.
I'd note, that the egress BFD system is expected to accept a BFD packet
with the destination IP address from the specified range without being
provisioned for the specific address from that range. Perhaps that makes
the use of this range possible even though its special handling is not
explicitly documented.

Best regards,
Greg

---

From: Alissa Cooper <[email-masked]>
Date: Wed, 18 Dec 2019 16:46:36 -0500

Erik, thanks for your review. Greg, thanks for addressing Erik’s comments. I entered a No Objection ballot.

Alissa

> On Dec 17, 2019, at 6:17 PM, Greg Mirsky <[email-masked]> wrote:
> 
> Hi Erik,
> thank you for your reviews and for sharing thoughts on the selection of the destination IPv6 address. Following recommendations from Adam, I've updated the document to use the proper representation of IPv6 addresses and refer to them as "IPv4-mapped IPv4 loopback addresses". These updates are in the attached diff.. Adam also noted that RFC 8504 doesn't have a similar wording regarding the handling of packets addressed to an address from 127/8 network as RFC 1812 (of course, referring to IPv4-mapped 127/8 addresses):
> I'd note, that the egress BFD system is expected to accept a BFD packet with the destination IP address from the specified range without being provisioned for the specific address from that range. Perhaps that makes the use of this range possible even though its special handling is not explicitly documented.
> 
> Best regards,
> Greg
> 
> 
> On Mon, Dec 16, 2019 at 9:19 PM Erik Kline via Datatracker <[email-masked] <mailto:[email-masked]>> wrote:
> Reviewer: Erik Kline
> <https://trac.ietf.org/trac/gen/wiki/GenArtfaq <https://trac.ietf.org/trac/gen/wiki/GenArtfaq>>.
> 
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