[address-policy-wg] Policy Change Request - Allow address allocations for anycast DNS operation

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
-- 
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