BFD over VXLAN: Trapping BFD Control packet at VTEP

Greg Mirsky <> Wed, 31 July 2019 12:48 UTC

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From: Greg Mirsky <>
Date: Wed, 31 Jul 2019 08:48:31 -0400
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Subject: BFD over VXLAN: Trapping BFD Control packet at VTEP
To: rtg-bfd WG <>, "T. Sridhar" <>, Dinesh Dutt <>, Joel Halpern <>,, Martin Vigoureux <>
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Dear All,
thank you for your comments, suggestions on this issue, probably the most
challenging for this specification. In the course of our discussions, we've
agreed to abandon the request to allocate the dedicated MAC address to be
used as the destination MAC address in the inner Ethernet frame. Also,
earlier using VNI 0 was changed from mandatory to one of the options an
implementation may offer to an operator. The most recent discussion was
whether VTEP's MAC address might be used as the destination MAC address in
the inner Ethernet frame. As I recall it, the comments from VXLAN experts
equally split with one for it and one against. Hence I would like to
propose a new text to resolve the issue. The idea is to let an operator
select Management VNI and use that VNI in VXLAN encapsulation of BFD
Control packets:

An operator MUST select a VNI number to be used as Management VNI. VXLAN
packet for Management VNI MUST NOT be sent to a tenant. VNI number 1 is
RECOMMENDED as the default for Management VNI.

With that new text, what can be the value of the destination MAC in the
inner Ethernet? I tend to believe that it can be anything and ignored by
the reciever VTEP. Also, if the trapping is based on VNI number, the
destination IP address of the inner IP packet can from the range 127/8 for
IPv4, and for IPv6 from the range 0:0:0:0:0:FFFF:7F00:0/104. And lastly,
the TTL to be set to 1 (no change here).

Much appreciate your comments, questions, and suggestions.

Best regards,