[dns-operations] Anycast enhancement, was: Re: Is anyone aware of the Community

Bruce Campbell bc-dns at vicious.dropbear.id.au
Thu Mar 22 19:20:25 UTC 2007

On Wed, 21 Mar 2007, Joe Abley wrote:

> Hi Calvin!
> On 21-Mar-2007, at 19:38, Calvin Browne wrote:
>> So, here's a suggestion to anycasters - under ipv4, you cast a whole
>> class c (I stand under correction here, and guess ipv6 would be even
>> more).

I just prefer to refer to an 'appropriately sized block', and leave it to 
the politicos to decide how big that is.

>> would it make sense to use virtual server technology (etc xen) to
>> allow separation of services at a virtual server level? or should this
>> be left to the application level? my guess is both are applicable.....
>> (or maybe this is already being done ;-) ) Scaling issues aside of
>> course.
> If I understand your question correctly, regardless of whether you
> use virtual servers or discrete physical servers, if you are
> numbering more than one *service* within the same anycast prefix you
> have a shared fate problem. It's not necessarily intractable, but it
> requires some thinking.
> This is discussed in RFC 4787 section 4.8.

off-by-one, check 4786 4.8 instead ;)

Of course, being _able_ to put a given _service_ on a seperate 
virtual/physical host implies that the service is already on a seperate IP 
address from other services provided by the same operator.

So if you, as a really-important-zone operator, wish to have greater 
control over how your zone is served by having your own machine 
(virtual/physical) doing the serving, ask your secondary providers for a 
dedicated IP address within their (anycasted) address space.

   Bruce Campbell.

   There are other advantages to doing so as well.

More information about the dns-operations mailing list