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177

answers:

2

Hi,

We are planning to have an application run on Amazon's cloud which requires a static IP for it to work. However it appears from Amazon's documentation that static IPs are NOT allowed...

http://aws.amazon.com/ec2/#features --> Elastic IP Addresses

http://developer.amazonwebservices.com/connect/message.jspa?messageID=65389

Allen / Posted: Aug 3, 2007 7:30 AM PDT in response to: Steve Isaacson ...

The machine's external IP address is essentially a static address. You will have it until your instance is terminated or until Amazon needs to renumber its network. This could be months or years from now, which in this day and age, is about as static as it gets.

http://docs.amazonwebservices.com/AmazonEC2/dg/2006-06-26/TechnicalFAQ.html#d0e7741

8.12. Can I use a static IP in my instances?

No. Your image must be configured as a DHCP client and it will be assigned an IP.

This however confused me a little bit: http://developer.amazonwebservices.com/connect/entry.jspa?externalID=1346 --> Introduction

Elastic IP addresses are static IP addresses designed for dynamic cloud computing. An Elastic IP address is associated with your account, not a particular instance, and you control that address until you choose to explicitly release it. Unlike traditional static IP addresses, however, Elastic IP addresses allow you to mask instance or availability zone failures by programmatically remapping your public IP addresses to any instance associated with your account. Rather than waiting on a data technician to reconfigure or replace your host, or waiting for DNS to propagate to all of your customers, Amazon EC2 enables you to engineer around problems with your instance or software by programmatically remapping your Elastic IP address to a replacement instance.

Is there any way that a machine instance can have a static IP address linked to it?

A: 

Elastic IP is the right thing to do for static IP. Whereas individual instances are configured via DHCP, and could technically be assigned a new IP address, your elastic IP never changes.

The elastic IP address is effectively a second address that you can assign to your instance alongside the one assigned via DHCP. One useful feature of elastic IP is that you can reassign it to a different instance transparently: if one of your instances fails, you can reassign the elastic IP address to a replacement instance with a single command.

Tim Robinson
As I understand it, the application itself needs to be on a system that has a static-ip. I dont think an elastic ip would work...
RubiCon10
Can you explain more? Elastic IP gives you the guarantee that address a.b.c.d will always route to your instance. Does your application need a stronger guarantee than that? (Does it inspect the hardware, for instance?)
Tim Robinson
Hi - the application documentation says that the minimum requirements are a static IP. It does not say why or what for... I'm emailing the tech support of the company to inquire more - whether its actually needed...
RubiCon10
The company says that a static IP is required...
RubiCon10
Without knowing why one is required, it's hard to say whether elastic IP will be sufficiently static. Maybe you could try it and see what breaks? :)
Tim Robinson
+2  A: 

In AWS-EC2 Console you can associate a Elastic IP. This is a static IP that is dedicated for you (until you have registered it and you pay for it).

No cost for Elastic IP addresses while in use

$0.01 per non-attached Elastic IP address per complete hour

$0.00 per Elastic IP address remap – first 100 remaps / month

$0.10 per Elastic IP address remap – additional remap / month over 100

This IP you can assign to your running EC2 instance.

See setup dialog: alt text

amra
Hi amra - would this be a formal "static IP" like what is required for an SSL cert for instance?
RubiCon10
(That's not what I need btw, but just trying to understand what this "static ip" could be used for)
RubiCon10