In a message written on Fri, Jul 02, 2004 at 11:16:08AM -0400, Joe Abley wrote:
In my opinion, the primary purpose of anycast distribution of nameservers is reliability of the service as a whole, and not performance. Being able to reach a server is much more important than whether you can get a reply from a particular server in 10ms or 500ms.
Well, you're right, but there's a practical matter to scaling the deployment. If you have 50 anycast servers, each doing 1 unit of work, and you list the anycast address 1 one non-anycasted address, there's a real possibility that the vast majority of clients out there will latch on to that one address, sending all 50 units of load towards it. So the question is not so much "is 500ms towards the server bad", it's "can I build a single server (cluster) that will take all the load worldwide when the client software does bad things." Of course, everyone I've ever seen talk about this is either referencing a lab test, or theory based on how the code works. I've seen very little real world measurements to show how this actually plays in the wild. If someone has anycast + unicast for a "busy" zone and can provide real distribution of queries data (particularly before and after an outage) that would be quite interesting. -- Leo Bicknell - bicknell@ufp.org - CCIE 3440 PGP keys at http://www.ufp.org/~bicknell/ Read TMBG List - tmbg-list-request@tmbg.org, www.tmbg.org