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Re: Intradomain DNS Anycast revisited
- From: Bill Woodcock
- Date: Fri Mar 25 01:27:31 2005
> 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?
No, because both routers are reached through the same L1/L2 medium, so
Quagga can't use link-state to determine reachability of the next-hop.
You could fix that by getting rid of the switches, and just having a bunch
of router interfaces facing two Ethernet interfaces on each server, which
would remove some points of failure, and would be a good idea if you can
spare the router interfaces... or you could use the OSPF which you're
already going to be running, to advertise a default from both routers to
each of the servers.
> 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 ?
Nope, no problem, particularly so long as the two routers are iBGP peers,
so they'll both (for the most part) have the same idea of what selected
> 3) Is there any requirement on BIND to fit to such
> multipath routing situation?
Nope. BIND doesn't know what's going on that far below it.