Re: Question on anycast IID range(s)

I think practically speaking the only to tell if an address on another node
is anycast or not is by the observable difference in the NA:

    https://tools.ietf.org/html/rfc4861#section-7.2.7

"""
   From the perspective of Neighbor Discovery, anycast addresses are
   treated just like unicast addresses in most cases.  Because an
   anycast address is syntactically the same as a unicast address, nodes
   performing address resolution or Neighbor Unreachability Detection on
   an anycast address treat it as if it were a unicast address.  No
   special processing takes place.

   Nodes that have an anycast address assigned to an interface treat
   them exactly the same as if they were unicast addresses with two
   exceptions.  First, Neighbor Advertisements sent in response to a
   Neighbor Solicitation SHOULD be delayed by a random time between 0
   and MAX_ANYCAST_DELAY_TIME to reduce the probability of network
   congestion.  Second, the Override flag in Neighbor Advertisements
   SHOULD be set to 0, so that when multiple advertisements are
   received, the first received advertisement is used rather than the
   most recently received advertisement.
"""

On Wed, 2 Jan 2019 at 08:51, Kerry Lynn <kerlyn@ieee.org> wrote:

> For practical purposes, particularly in light of RFC 7136, should one
> consider an anycast address to be any that ends in dfff:ffff:ffff:ff80-
> dfff:ffff:ffff:ffff OR ffff:ffff:ffff:ff80-ffff:ffff:ffff:ffff?
>
> The phrase in RFC 2526 that's causing confusion for me is
> "Specifically, for IPv6 address types required to have to have
> [sic] 64-bit interface identifiers in EUI-64 format ..."  To my
> knowledge, there are address types that require a 64-bit IID,
> but it seems we've been systematically trying to deprecate
> *EUI-64 format* IIDs.  In any case, there's nothing to prevent a
> mix of EUI-64 or *other* format IIDs in the same subnet as far
> as I'm aware.
>
> Thanks, Kerry
>
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