Anycast in Unicast IPv4

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Dec 15th, 2008
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I do have nation wide network, and Have two datacenter located in two different place, so can I have my east part site having communicated with eastern side datacenter and same thing for the western side. and can i put my webservices or any application servers located at both the site with the same IP address so on the base of metrics eastern part can access the eastern datacenter and western part can access the western data center! and if eastern data center goes down then eastern part still have access to the western data center? I am looking for kind of multicast anycasting in unicast environment!!!


Devang Patel

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Giuseppe Larosa Mon, 12/15/2008 - 09:59
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Hello Devang,

you can do this but be aware that users sessions will hang up just after a switchover because the sockets they were using are not present in the other cluster.

This can be acceptable or not depending on the type of application involved.

Besides this all servers will have to be structured accordingly with a user front end (the anycast address), distinct backend and management interfaces.

All this for management and for disaster recovery: you may need to synchronize databases among the two datacenters.

The constraint on network topology is that no user has to see two equal paths to destination or on east or on west side

Hope to help


Laurent Aubert Mon, 12/15/2008 - 10:05
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Hi Devang,

Sure it should work. But you may have issue for troubleshooting as you can't trust the IP address of your server (not an 1:1 relationship). Same issue if you need access to a specific server via the network

You may want to consider using load-balancer boxes instead with a single virtual address.

my 2 cts




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