Regd Solaris redundancy ( Ip address takeover )
2007-12-25 3:56:00
I am doing some research for a mirroring/failover project. I am
looking at different ways to get the clients to stop communicating
with the primary server and start communication with the secondary
server.
The best way to accompilsh this seems to be with a 3 IP address
solution (This would be for a two node failover). Each node has a
unique IP address assigned to it. The third IP address is the floating
IP address.
This floating IP is first aliased by the primary server. Once a
failure is detected the secondary node then aliases the IP address.
The trick is to then get the clients to update their ARP cache with
the new MAC address/IP address.
This is where the gratuiyous ARP comes in. You would need to get
your secondary node to send out an ARP response even though no ARP
request was made. When the clients see that the IP address is already
in their ARP cache and new ARP response are being sent they should
update their cache. This technique is also used in IP spoofing so some
routers and other equipement ignore the ARP response, however I
believe alot of router allow you to configure this option.
The nice thing about using the third IP address is that your
primary server can boot back up on it's own IP address not causing any
IP address conflicts. Then with some simple check the primary server
can decide if it needs to re-aliase the floating IP address or whether
it will become the secondary sever now.
Can anyone please help me in how the above theory can be implemented
in solaris servers ?
Thanks and Regards,
Lakshman
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