[dns-operations] Quick anycast primer

Jim Reid jim at rfc1035.com
Fri Jul 14 11:57:37 UTC 2006

On Jul 14, 2006, at 12:38, John Payne wrote:

> On Jul 14, 2006, at 4:24 AM, Jim Reid wrote:
>> On Jul 14, 2006, at 08:41, Steve Gibbard wrote:
>>> In a typical anycast cloud, there are several servers in several
>>> locations sharing a service address.  When all servers in the  
>>> cloud are up, and
>>> routing to all of them is working properly, queries sent to that
>>> service address are responded to by the topologically closest  
>>> server.
>> ....modulo peering agreements/policies.
> Hence topologically closer and not geographically or  
> anythingelseally closer

Which as I said depends on the definition of "topologically closer".  
You seem to favour a definition based on what the routing tables say:  
a logical topology if you will. Which is fine, up to a point. But  
there's also a physical topology which is where the cables go and the  
paths packets take.

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