Swede,
The anycast hack is pretty well understood, but it has some
serious limitations. As both drafts note, the same AS must be used to
announce the route (either because a single administrative entity
truly controls all instances, or in a shared-control environment).
You also must be wary of deploying services on the shared unicast
address which require TCP. In the current draft-ietf-dnsop-hardie,
that's stated this way:
One potential problem with using shared unicast addresses is that
routers forwarding traffic to them may have more than one available
route, and those routes may, in fact, reach different instances of
the shared unicast address. Because UDP is self-contained, UDP
traffic from a single source reaching different instances presents
no problem. TCP traffic, in contrast, may fail or present
unworkable performance characteristics in a limited set of
circumstances. For split-destination failures to occur, the router
forwarding the traffic must both have equal cost routes to the two
different instances and use a load sharing algorithm which does
per-packet rather than per-destination load sharing.
You don't describe the nature of the services you plan to
deploy, but unless it is the DNS, I would be concerned about your
taking too much guidance from my draft.
regards,
Ted Hardie