I think, I have found the answer to one of my questions by myself: GRE-tunneled Anycast with a far remote outer address and a locally scoped inner anycast address.
Heiner In einer eMail vom 22.04.2009 00:29:24 Westeuropäische Normalzeit schreibt [email protected]: In einer eMail vom 21.04.2009 23:54:19 Westeuropäische Normalzeit schreibt [email protected]: On Tue, Apr 21, 2009 at 4:00 AM, <[email protected]> wrote: > As I understand Anycast is about delivery to one out of multiple > destinations within a given scope. Hi Heiner, I would have said "closest one from the set of valid destinations," but your version is good enough. More precisely "closest one from the set of valid destinations with respect to the source," > Where is the center point of this scope ? Is it always the location of the > source ? I don't understand the question. What is a center point wrt routing? My question is: with anycast do we always understand the above, or could it also be any particular destination within the scope of an indicated remote location like a different continent? What do we understand by Anycast in the future ? Some one must do the mapping to a specific Unicast address? Is it always the ingress ? Or can't there be reasonable anycast services which require to send the data to some far distant anycast server where it will be mapped to some local unicast addresss ? > What are the requirements for Anycast in a new architecture? Well, that's the crux of the discussion, isn't it? Anycast and unicast are identical in every respect in the current architecture. How do we bound the unforeseeable consequences if that isn't true in the new one? I'm getting ready to introduce an anycast route into the table in order to implement a "continuing operations" system with three sites half a world apart. "Continuing operations" is a fancy phrase for "disaster recovery," something that became really popular almost 8 years ago. Once a packet hits any of the always-running sites, a VPN takes it back to the site with the servers flagged "best" for that particular address, so holistically its unicast but from the perspective of the Internet core its anycast from three distinct locations. Would this have any hope of working right in an architecture that didn't accommodate anycast? How many such uses are out there, ready to impede the deployment of the unwary plan? Sorry, I don't understand what you are hereby saying. Heiner Regards, Bill Herrin _______________________________________________ rrg mailing list [email protected] http://www.irtf.org/mailman/listinfo/rrg
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