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I did a lot of experiment with heartbeat, corosync and pacemaker for IP FailOver which I have to do with Public IP. I did more than one ip failover(VIPs) with two nodes, also with three nodes BUT using Private IP(s) as VIPs.

I tried this using vbox virtual machines and everything was ok as far as I was doing with Private IP addresses but when I started thinking of doing for Public IP failover(which I'm assigned from ISP), I got stuck, confused questioning myself.

I have some machines in LAN interconnected with the help of Home Router on which DHCP enabled. I could not go further thinking how do I do failover for the Public IP which I am assigned.

My questions is,

How do I do the same failover for the Public IP address which I'm assigned? with one more router? if yes how?

Any help is greatly appreciated. Thanks!

Update

Related to my router:

  • Ok, need two routers, how to know/buy if router supports clustering?
  • Do I really need two ISP(public ip) links to failover the single public ip?.
  • After all, I think I should do a Port Forwarding on a router to VIP(private ip) which I have configured for failover using heartbeat on servers. How should I proceed for another VIP? is that on another router?
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2 Answers

up vote 6 down vote accepted

So you need a method to survive some kind of failure. Failure of what?

Failure of your router

You need:

  • a cluster of two routers; pick ones that support clustering (passive-active is enough)
  • two physical links from your ISP
  • all servers should connect independently to both routers

Failure of either your router or ISP (done with DNS)

You need:

  • two ISPs
  • two "public" IPs (that is, Internet IPs)
  • a DNS server with
    • round-robin,
    • and a very small TTL
    • and capable of automatic deletion of IP record when that IP becomes unavailable

Failure of either your router or ISP (done with BGP)

You need:

  • two ISPs
    • each ISP to support BGP protocol - usually the cost is prohibitive
  • two "public" IPs
  • two routers with BGP support

With BGP you have much faster failover of incoming traffic than with DNS.

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See also serverfault.com/questions/63788/… –  kubanczyk Jan 28 '12 at 20:16
    
Thanks for good info!, finally understood I should do it at router levels especially on my routers and I couldn't do anything if ISP's is down. Based on your answer I got few more questions, I update the question, please answer if you have time. –  user53864 Jan 29 '12 at 2:48
    
Just got a basic idea! –  user53864 Jan 30 '12 at 3:10
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Is your goal to stay online in case of modem/router failure? If yes, this gets very complicated in that the IP address assigned to you is assigned to that particular modem.

If you have a domain name that you are using for this purpose you could get redundant internet service, and a router that can handle multiple WAN ports with failover. Multitec makes a line of routers for this purpose. You can then set up Round-Robin service on the domain with your provider.

If you do not already have a domain, you could get one from a dynamic dns site like http://no-ip.com or dyn.com. Most of these routers have options in their firmware for keeping a site like this updated.

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I think generally we'll have to assign in the router some where in the configuration page if have static ip. I'm thinking how to interconnect two router and share the public ip for failover just like we do it on the servers for ip failover. If router which is said to support clustering(as kubanczyk said) does this work, then I've no work on routers. But still I might have to do port forwarding to the VIPs(private) and don't know exactly is this the right way. –  user53864 Jan 29 '12 at 3:16
    
At this point you should speak to your ISP to see what they support, and assess from there what your fault tolerance is. –  Shawn Jan 29 '12 at 13:08
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