這篇文章的標題很動人，但內容我看得不是很懂。不知是因為我不懂 IPv6 還是不懂 Cloud Computing ... 有看過的朋友能否幫忙解惑一下？ Sincerely, Solomon Feb. 27 [超連結]: http://www.itworld.com/networking/85651/ipv6s-killer-app-finally-cloud-computing November 22, 2009, 10:24 PM — IPv6 has been an approved standard for over a decade now. But its adoption has suffered from lack of a compelling reason to deploy it. Since the future scalability of the Internet depends on our adopting it soon, we should be on the lookout for so-called “killer applications” where its benefits over IPv4 can help us solve real world problems today. That will help get IPv6 rolled out before we run out of IPv4 addresses and experience all the problems that will cause. It is similar to incentivizing the use of renewable energy before cheap fossil fuels run out so the transition is less painful for all involved. This article discusses one such killer app for IPv6: Infrastructure-as-a-service cloud computing systems such as Amazon’s EC2. Cloud computing solves many of the problems of maintaining and growing a complex server infrastructure. But it does so in a way that introduces a few new ones. One of the biggest challenges is IP addressing. IPv4, the underlying protocol powering the Internet as we know it today, as well as just about every other computer network we use on a daily basis, was not designed to accommodate the elastic nature of the cloud. Server instances need a way to find each other on an IP network, but it is not practical to assign every client account a static, publically routable IPv4 subnet, especially as they become scarcer. Depending on the cloud provider’s architecture, it is also sometimes advantageous not to use the public IPv4 address even when there is one available (due to performance and/or bandwidth cost considerations). In order to demonstrate how IPv6 can help with this, let’s start with an example scenario of how it works now on EC2. Amazon’s Elastic Compute Cloud (EC2) service is undeniably the leader in infrastructure-as-a-service cloud computing options. When you launch an instance, it is dynamically assigned an IPv4 address in the 10.0.0.0/8 private subnet. If Amazon is actually using a subset of that class A block, they’re not saying. So system administrators have to assume the entire 10.0.0.0/8 subnet is off limits for anything else (such as VPN subnets). A routable, public IPv4 address is also assigned so you can access the instance from outside Amazon’s network in a 1:1 NAT configuration. You can optionally request that this come from a pool of static addresses reserved for your use only. Amazon calls these Elastic IPs and charges for reserving them (though not while they’re actively in use). It may be tempting to think assigning an Elastic IP to each of your instances is a good solution, but there’s a downside. When you access an EC2 instance from another instance (for example, when your PHP-enabled web server wants to contact your MySQL database server), it’s a good idea to use the 10.0.0.0/8 address whenever possible. --

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