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Re: Intradomain DNS Anycast revisited

  • From: Peter John Hill
  • Date: Sun Mar 27 11:47:42 2005

On Mar 26, 2005, at 1:41 PM, just me wrote:
  1) should each dns cache server be configured a static
  default route (0.0.0.0/0.0.0.0)? If server-(1,3) is
  configured statically to use
  router-1 as default router, will Quagga make it use
  router-2 when router-1 is not reachable?

configure a loopback interface on your dns servers and advertise a route to that loopback address to your connected routers... Why the hell do you want to use static routes when you don't need to... Yuck

  2) If each server is configured two default router (
  router-1 &
  router-2), or each server learn route 0.0.0.0/0.0.0.0
  by OSPF ( our border router inject default route into
  OSPF ); there should be
  two equal cost path to 0.0.0.0/0.0.0.0 on each DNS
  server, the DNS server should disperse any outgoing
  packets onto the two paths, will
  that do harm to  DNS service ?
Servers a cheaper than good routers... Why don't you just have your dns server connected to one router.... If you want dns servers on multiple subnets, spend a couple of grand and get a cheap 1U dell server for your other rack... Why do you need to worry about default routes? You are running a dynamic routing protocol on your dns server. Anycast dns pretty much relies on ospf working... Hell, you don't need any default gateway on your host... Let you quagga worry about routing...

Set up your ospf area as an nssa.... Your dns server only needs to LEARN default from the connected routers... You will be doing a 7-5 conversion on your asbrs.

  3) Is there any requirement on BIND to fit to such
  multipath routing situation?

What does bind care? We are talking unicast... If the packet can get to your dns server, bind can probably get the answer back. You are making this much more difficult than it needs to be....

http://www.net.cmu.edu/pres/anycast

Check out this presentation....

Peter


  Joe

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