BFD for vxlan Destination MAC field (was Re: draft-ietf-bfd-vxlan IESG status)

Jeffrey Haas <jhaas@pfrc.org> Mon, 20 July 2020 21:26 UTC

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Date: Mon, 20 Jul 2020 17:37:35 -0400
From: Jeffrey Haas <jhaas@pfrc.org>
To: Greg Mirsky <gregimirsky@gmail.com>, Donald Eastlake <d3e3e3@gmail.com>
Cc: The IESG <iesg@ietf.org>, bfd-chairs@ietf.org, draft-ietf-bfd-vxlan@ietf.org, rtg-bfd WG <rtg-bfd@ietf.org>
Subject: BFD for vxlan Destination MAC field (was Re: draft-ietf-bfd-vxlan IESG status)
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On Wed, Jun 17, 2020 at 03:52:14PM -0400, Jeffrey Haas wrote:
> >> Proposed solution: A MAC value should be chosen that is well known and the
> >> text would become:
> >> 
> >> "Destination MAC: A Management VNI, which does not have any tenants, will
> >> have no dedicated MAC address for decapsulated traffic.  The value
> >> X:X:X:X:X
> >> SHOULD be used in this field."
> >> 
> >> SHOULD might need to be MUST.  Since a partial motivation for permitting
> >> the
> >> flexibility in the specification to NOT use the management VNI is desired=
> > ,
> >> MUST might be inappropriate.
> >> 
> > GIM>> Accepted the suggested text. I agree that the flexibility to not use
> > the Management VNI is permitted in the specification and thus SHOULD in the
> > text is consistent with that scenario. How would we pick the MAC address?
> 
> I am out of my area of expertise and I was hoping someone in the IESG can offer a fix. :-)  I am copying Donald Eastlake since he's the designated expert for the IANA MAC address block.
> 
> Donald, review of the thread may be useful, but tersely the need is to have a well known MAC address that can be placed in this vxlan PDU that is literally a placeholder of "not to be used for forwarding".  The packet arrives at the endpoint and, if not immediately accepted, would be dropped.
> 
> If there is no well known MAC that could be used for such a behavior, perhaps an address from the IANA block may be used?
> 
> While I suspect the IANA mac documentation range could be used, IANA may not appreciate that.

Donald is not responding to emails.  Considering I've been similarly bad
about responding, that's forgivable.  However, in the interest of advancing
the document, I'd like to make a proposal.

https://www.iana.org/assignments/ethernet-numbers/ethernet-numbers.xhtml

Proposed text:

: Destination MAC: A Management VNI, which does not have any tenants, will
: have no dedicated MAC address for decapsulated traffic.  The value
: [TBD1] SHOULD be used in this field.
: 
: IANA Considerations:
: 
: IANA is requested to assign a single MAC address to the value TBD1 from the
: "IANA Unicast 48-bit MAC Address" registry from the "Unassigned (small
: allocations)" block.  The Usage field will be "BFD for vxlan" with a
: Reference field of this document.



-- Jeff