nanog mailing list archives
Re: [dnsop] DNS Anycast revisited (fwd)
From: "Patrick W. Gilmore" <patrick () ianai net>
Date: Tue, 3 May 2005 21:58:37 -0400
On May 3, 2005, at 7:38 PM, Edward B. Dreger wrote:
PWG> Date: Tue, 3 May 2005 18:03:12 -0400 PWG> From: Patrick W. Gilmore PWG> NB [translation, "operational content"]: Akamai does not use any PWG> anycast for HTTP. I am not at all certain why Paul is telling usPWG> this is a bad idea, since we don't do it. Then again, we might in PWG> the future, I am not privy to every decision in the company. (No, PWG> that is not a "hint", I really do not think we will do anycast HTTPPWG> for content delivery, but I also really do not know everything we PWG> will do in the future.) One also should distinguish between TCP _to_ an anycasted address andTCP _from_ an anycasted address. The latter is trickier, as asymmetricrouting increases the chances that the session will need to be transferred to another pod:
Just to make life fun, there is the whole "anycast a bunch of name servers, each with different zone files pointing at local HTTP servers". Since the "anycast" portion is over UDP, it avoids a lot of the problems (real or otherwise) mentioned here, and the HTTP is still unicast but distributed and can be made resilient to failure.
Of course, the DNS backend is then .. uh .. "de-coherent"? :-) But it works, and works well, in many currently operational configurations.
Does PPLB (or anything else) break this? I'm certain I could find things that would break this if I looked hard enough. But as I've said many times, reality trumps NANOG posts. Since this is a _working_ configuration today, I would say that disproves any claims that it cannot or will not work.
-- TTFN, patrick
Current thread:
- Re: [dnsop] DNS Anycast revisited (fwd), (continued)
- Re: [dnsop] DNS Anycast revisited (fwd) Patrick W. Gilmore (May 03)
- Re: [dnsop] DNS Anycast revisited (fwd) Nicholas Suan (May 03)
- Re: [dnsop] DNS Anycast revisited (fwd) Paul Vixie (May 04)
- Re: [dnsop] DNS Anycast revisited (fwd) Todd Vierling (May 03)
- Re: [dnsop] DNS Anycast revisited (fwd) Edward B. Dreger (May 03)
- Re: [dnsop] DNS Anycast revisited Rodney Joffe (May 03)
- Re: [dnsop] DNS Anycast revisited Todd Vierling (May 03)
- Re: [dnsop] DNS Anycast revisited Paul Vixie (May 04)
- Re: [dnsop] DNS Anycast revisited (fwd) Edward B. Dreger (May 03)
- Re: [dnsop] DNS Anycast revisited (fwd) Patrick W. Gilmore (May 03)
- Re: [dnsop] DNS Anycast revisited (fwd) Edward B. Dreger (May 03)
- Re: [dnsop] DNS Anycast revisited (fwd) Patrick W. Gilmore (May 03)
- Re: [dnsop] DNS Anycast revisited (fwd) Edward B. Dreger (May 03)
- Re: [dnsop] DNS Anycast revisited (fwd) Patrick W. Gilmore (May 03)