[dns-operations] "first class" anycast?

Paul Vixie paul at vix.com
Sat Jul 15 22:06:09 UTC 2006

i won't criticize per heldal for feeding trolls here, since he already knows,
and he usually goes a good job.  and furthermore, his off-topic excursion is
a fine excuse for a new thread: is "1st class anycast" like "tier 1 backbone"?

> To stray further OT:
> 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 think you're factually wrong here.  ultradns has always controlled their
own infrastructure in the way you describe.  so, whatever problem you thought
you had observed, was due to something else.  but we digress, really, from:

> This is why the only "first-class" anycast providers are providers with a
> network footprint large enough to cover all their anycast locations. 

not only do i disagree with your judgement as to first-classitude, but also,
i contest your redefinition of terms.  if someone has a backbone and is able
to advertise a netblock in location X which really exists in location Y, then
it's not really anycast at all.  even if they usually optimize by creating
the service in both location X and location Y, by definition of the word, if
it's possible to reach location Y due to an advertisement at location X, then
it's not formally an "anycasted service."

> These providers are the only ones who reliably can provide more than one
> anycast service within each announced prefix. Different size network have
> different properties. Certain properties come with scale, and can't be
> bought separately.

i completely and totally disagree.  looking at www.root-servers.org i see a
number of "first class" or "tier 1" anycasted DNS services which have (by
definition) no interior connectivity.  this isn't "just as good", it's better
than a dns service network with interior connectivity, and will remain so
until IP networks run faster than light, backbone routers have no moving
parts, and backbone engineers go home at least once a day to take a bath.

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