Hi Alexey,
--- kuznet@xxxxxxxxxxxxx wrote:
> > However, nothing prevents the
> > user from using any unicast address as an anycast address.
>
> It is impossible even to say "someone uses an unicast as anycast."
> Think a bit, anycast != unicast only from receiver viewpoint.
> If receiver thinks that an address is anycast, it __ anycast.
>
Note, I said unicast address as anycast address. Of course, the
unicast mechanism is different from anycast. Also, there is no
need for the receiver to be aware of the fact that it has an
anycast address - it could be part of an anycast group without
it's knowledge.
> are useless for any serious applications beyond scope of stateless
> datagram services f.e. name services.
Use of simple anycast requires some additional care, even for things
like dns. However, depending on your goal, there are -simple- tricks
that can be played to possibly meet certain requirements (for e.g,
automatic failover) for _certain_ stateful applications. Nevertheless,
I concur that anycast is not appropriate for general usage by users
who are not familiar with it's implications, except where formal
definitions have been made, such as anycast PIM-RP's.
I'd written up something a while ago describing one such trick, which
I'll be glad to dig up & send to you if you are interested - let me
know.
>
> I am afraid you tell about _unicast_ assigned to multiple hosts.
rfc1546 describes this as one possible anycast address allocation
mechanism.
> This case has nothing common both with anycasts and with any
> other practice ever approved by IETF to nowadays.
Actually, there was a BoF in the last IETF to discuss anycast (both v4
and v6) & it's applications. While there was no commitment to pursue
anything formal yet, there was no intent to prohibit it's use within
individual administrative domains either.
cheers!
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