Last Call Review of draft-ietf-bess-evpn-na-flags-05
review-ietf-bess-evpn-na-flags-05-secdir-lc-vucinic-2020-09-01-00

I reviewed this document as part of the Security Directorate's ongoing effort
to review all IETF documents being processed by the IESG. These comments were
written primarily for the benefit of the Security Area Directors. Document
authors, document editors, and WG chairs should treat these comments just like
any other IETF Last Call comments.

The document specifies an extension to an Ethernet Virtual Private Network
(EVPN) MAC/IP advertisement by defining an EVPN Extended Community carrying
flags relevant to the ARP/ND resolution.

The abstract of the document does not include enough background context for it
to be useful to the general audience. Otherwise, the document is well written.

The security considerations section should be further elaborated. For instance,
the section includes a discussion on a possible misconfiguration of Router (R)
/Override (O) flags but the discussion is limited to the fact that the
misconfiguration of an IPv6/MAC binding on a given Provider Edge device (PE)
will propagate, through the means of IPv6 Neighbor Solicitation messages, to
other PEs in the same broadcast domain. I would like to understand better the
effect of each flag, i.e. what kind of behavior in the network can an attacker
cause by changing one of these flags on a particular device or in transit?