Don't you think the policy ought to be more relaxed and allow the server manager for the zone to decide how many of their servers they want to anycast? Joao On 11 Jun, 2004, at 10:25, Gert Doering wrote:
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