Tuesday, November 10, 2009

anycast dns

Anycast Addr: 1.2.3.4
Local DNS Server: 4.3.2.1

Unix
----
* vi /etc/sysconf/networks-scripts/ifcfg-lo:1

DEVICE=lo:1
IPADDR=1.2.3.4
NETMASK=255.255.255.255
ONBOOT=yes
NAME=loopback

* /etc/init.d/network start
* Turns on lo:1





Router
------
; monitor DNS resolution every 30 seconds
ip sla monitor 100
type dns target-addr my.example.com name-server 4.3.2.1
frequency 30

; start the monitoring session and go forever
ip sla monitor schedule 100 life forever start-time now

; static route for anycast to local dns server
ip route 1.2.3.4 255.255.255.255 4.3.2.1 track 100

; tie the sla check to the static route
track 100 rtr 100

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