

Thought this was impossible? IP address failover across cloud/provider networks - jbrendel
http://blog.vcider.com/2012/04/multi-cloud-ip-address-failover-with-heartbeat-and-vcider/

======
jbyers
It's an interesting use of an overlay network but the title of this post is
misleading.

This is the failover of a private IP behind a virtual network gateway. The
failover happens at layer 2 using the same gratuitous ARP you might send to a
local switch but over a virtual network. The resulting network has properties
that might be interesting to a private network service (especially one that
cannot easily be proxied) but less so for public-facing services.

If your application speaks HTTP, a health-checking proxy server like haproxy
on the gateway could perform the same service.

If your application is used by the public internet, your gateway machine(s)
and network(s) between the gateway and application become the weak links. The
traditional fallback would be low-TTL DNS.

~~~
jbrendel
I wouldn't exactly say the title is misleading, because it still is an address
failover between cloud networks. But your points about the public addresses is
of course correct.

The key application here is for those who wish to establish hybrid clouds,
want to "cloud burst" their enterprise capabilities, or - as the opening
sentence of the article explains - about "[organizations] moving part of
[their] network and server infrastructure into the cloud".

And especially for those internal enterprise applications, running an HTTP
proxy is not always possible.

~~~
jbyers
You're right. I read the article through a public-internet lens -- a difficult
bias for me to shake. :) I can definitely see the value for enterprises. I do
very much like that the application servers are using the same tools they
would if they were neighbors in a rack.

------
rdw
Am I misunderstanding, or does this still have a single point of failure at
the gateway machine?

~~~
jbrendel
In this simple example, you would have a single point of failure for the
enterprise machines. But not any more than your enterprise's routers or
Internet connection represent single points of failure.

However, you can have multiple gateways (and thus alternative routes).
Furthermore, the IP address failover will instantly be noticeable to any other
machine you have in the virtual network.

------
chris_marino
There is still the issue of replicating content, but that's something that can
be handled in a number of different ways, depending on the requirements.

