Hi Pekka, I'm answering on your e-mail, but the same issue has appeared a couple of times: On Wed, Jun 09, 2004 at 12:38:45PM +0300, Pekka Savola wrote:
One /24 per zone operator. [..]
This is unacceptable for redundancy reasons. If the routing for the /24 hiccups (e.g., someone advertises the prefix but drops the packets), all the nameservers will down for people behind that ISP? If you anycast something, there will have to be a backup option as well.
The idea is not to put *all* name servers for a given zone into anycast space. The idea is to have a number of unicast servers (as many as fit into the delegation UDP packet, minus 1) and in addition to that, an anycast server with "many instances". So if the anycast /24 hickups, the client resolver will treat this as it will treat any failure of one of the auth DNS servers -> fall over to the next nameserver listed. Of course it's open to debate whether it might be desireable to permit "many different anycast networks for a single zone", or even "anycast all of the servers" (with individual networks). The current idea is conservative and proposes "one anycast netblock". Gert Doering -- NetMaster -- Total number of prefixes smaller than registry allocations: 60210 (58081) SpaceNet AG Mail: netmaster@Space.Net Joseph-Dollinger-Bogen 14 Tel : +49-89-32356-0 80807 Muenchen Fax : +49-89-32356-299