[dns-operations] Too Open (Was: OpenDNS makes your Internet work better

[Rodney Joffe]

On Jul 20, 2006, at 11:23 AM, Joe Abley wrote:

>
> On 20-Jul-2006, at 11:47, Florian Weimer wrote:
>
>> * Per Heldal:
>>
>>> The issue with UltraDNS desribed in this thread relates to the
>>> fact that
>>> they used multiple anycast IP's in the same address-block. You get
>>> problems if you do that and don't control the infrastructure
>>> interconnecting the various anycast locations.
>>
>> I don't see what you gain from controlling those interconnects.
>
> You get to route requests for 199.212.90.1 to a different node if
> 199.212.90.1 is unavailable locally, while 199.212.90.3 still works.

You can still do that if you don't "control the interconnects".  In  
my limited experience I've never designed any infrastructure poorly  
enough to need this capability, even though I have had control over  
the "interconnects" for most of my projects in the last 12 years.  
Including UltraDNS.

>
>> You
>> can't use intra-AS connections anyway because you'd need to run an
>> IGP, and your typical IGP is a distributed single point of failure.
>
> Avoiding the shared fate of an IGP between nodes is a win in many
> respects, but I wouldn't characterise it as a fundamental no-no.
>
> As with most things, the cost/benefit implications of individual
> design decisions vary widely according to exactly what you're trying
> to accomplish. Anycast is a wide umbrella, and generalisations are
> often impractical.

s/impractical/of no practical use.