North American Network Operators Group

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Re: Anycast 101

  • From: Iljitsch van Beijnum
  • Date: Fri Dec 17 07:13:05 2004

On 17-dec-04, at 12:25, Stephane Bortzmeyer wrote:

but even if 5 or 8 or 12 addresses become unreachable the timeouts
get bad enough for users to notice.

We can turn this into a Good Practice: do not put an instance of every
root name server on any given exchange point.

Actually, this is only a theoretical issue, the current maximum seems
to be only three (at the LINX in London).
Well, there may be only three "at" the LINX, but from where I'm sitting, 7 are reachable over the AMS-IX, 4 over ISP #1 and 1 over ISPs #2 and #3, respectively.

Interestingly enough, b, c, d and f all share this hop:

6 portch1.core01.ams03.atlas.cogentco.com (195.69.144.124)

(195.69.144.0/23 is the AMS-IX exchange subnet.)