North American Network Operators Group
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Re: Content Delivery Networks

  • From: Patrick W. Gilmore
  • Date: Tue Aug 07 09:10:00 2007

On Aug 7, 2007, at 3:59 AM, Michal Krsek wrote:

5) User redirection
- You have to implement a scalable mechanisms that redirects users to the closes POP. You can use application redirect (fast, but not so much scalable), DNS redirect (scalable, but not so fast) or anycasting (this needs cooperation with ISP).

What is slow about handing back different answers to the same query via DNS, especially when they are pre-calculated? Seems very fast to me.

Application redirection is far, far slower. (I am assuming you are talking about something like HTTP level redirects. Did you mean something else?)

As for anycast, with your own backbone, you don't need any cooperation. Even if you don't, the cooperation you need from your providers & peers is minimal at worst. (At least relative to writing the code for, say, DNS redirection.) But anycast assumes "BGP knows best", and we all know that is not even close to the truth.

--
TTFN,
patrick