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

Joe Abley jabley at ca.afilias.info
Thu Jul 20 18:23:46 UTC 2006

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 to a different node if is unavailable locally, while still works.

> 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.


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