拥抱未来网络：规划IPv6 - CSDN文库

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"Planning for IPv6: Join the New Internet" 是一本由Silvia Hagen编写的关于IPv6规划的书籍，旨在帮助读者理解和适应IPv6这一新一代互联网协议。该书由O'Reilly Media出版，适合教育、商业或销售推广使用，并提供在线版本。 IPv6是互联网协议版本6（Internet Protocol Version 6）的简称，是互联网协议IP的最新版本，旨在解决IPv4地址枯竭的问题。IPv6与IPv4相比，提供了几乎无限的地址空间，采用128位地址长度，可以分配大约3.4x10^38个唯一地址，远超过IPv4的43亿个地址。这使得全球的每粒沙子理论上都能拥有一个独立的IP地址。 IPv6的引入还带来了其他改进，包括更高效的路由、内置的QoS（服务质量）支持、增强的安全性、简化头部格式和自动配置能力，这些特性有助于网络管理和维护。IPv6的自动配置功能，如SLAAC（Stateless Address Autoconfiguration）和DHCPv6，使得设备能更容易地接入网络，减少了手动配置的需求。书中可能涵盖了以下知识点： 1. IPv6地址结构：理解16位块的表示法（冒分十六进制）以及如何解析和编写IPv6地址。 2. 地址类型：全球单播地址、链路本地地址、站点本地地址、多播地址等，及其在不同场景中的应用。 3. 隧道技术：如何通过IPv4网络部署IPv6，如6to4隧道、ISATAP隧道和GRE隧道等。 4. IPv6过渡技术：如双栈、DS-Lite、NAT64、464XLAT等，用于平滑过渡到IPv6。 5. IPv6路由与寻址：路由前缀、默认路由、路径选择策略及路由表管理。 6. 安全性：IPv6中的内置安全机制，如IPsec（Internet Protocol Security）以及如何实现端到端加密和身份验证。 7. 服务配置：DNS64、NDP（邻居发现协议）和DNS的IPv6扩展。 8. 移动性和漫游：移动IPv6（MIPv6）以及移动网络中的IPv6应用。 9. 实施策略：企业级IPv6部署的步骤、最佳实践和案例研究。这本书对于网络管理员、IT专业人员、系统架构师以及任何需要了解和实施IPv6的人群来说都是宝贵的资源。通过深入学习，读者将能够规划和管理自己的IPv6网络，确保顺利过渡到新的互联网时代。

CHAPTER 1

The Business Case

In this first chapter, I’ll discuss the business case and try to put it in a larger context

than usual to open the discussion for new perspectives and opportunities. Resolving

the business case discussions and putting the integration of IPv6 in the right context

paves the way for you to actually focus on the demands of planning for a successful

integration.

Many people hesitate to start the planning phase, probably because it often seems to

be an insurmountable task, with challenges that are way too complex to even start

thinking about it.

While it is true that integration in a larger network is not a no-brainer and takes a lot

of time and careful planning, there is no need to panic or think that you can’t handle

it. Every decent engineer who mastered the introduction of DHCP, VPNs, and NATs

will also master the introduction of IPv6. The difference is that IPv6, as the transport

protocol, touches every component in the network, so the complexity of integrating it

comes from having to consider all the interactions between the different network com-

ponents and services.

But the process can be broken down into single, doable steps, and you don’t have to

complete them in three months if you start early enough. This book provides an outline

to help you determine how you want to go about tackling it.

The Inevitable Business Case Discussion

The discussion around the lack of a business case for IPv6 is historically the most used

good reason to avoid integrating IPv6. The root of this argument seems to lie in the

combination of misunderstandings and a lack of context.

A business case addresses, at a high level, the business need that the project seeks to

meet. It addresses the reasons for the project, the expected business benefits and risks,

the options considered, and the expected costs of the project.

1

To define a business case, you must specify the parameters that qualify it, and what

constitutes a valuable business case may differ depending on the corporate culture. In

other words, what might qualify as a substantial business case in one corporate culture

may not be considered a business case in another culture because the corporate values

are different.

In general, we can say that IPv6 is part of evolving our infrastructure, evolving the

network that transports all data— it is the future highway for our data. So asking for

a business case for IPv6 is like asking for the business case of running a network. But

running our businesses without using scalable, high performance networks is not really

an option anymore. So there is not much choice, we must continue to invest in evolving

our networks, just like we have done since the early days of running networks; other-

wise, they will stop providing useful services for our businesses and hinder our com-

petitiveness at some point in the near future.

The Human Capacity for Predictions and the Business Case of Evolution

Our business case calculations and the common opinion that IPv6 has no business case

are based on expectations and predictions. What we think will be happening in three

to five years is what we base our judgments on.

If we look at history, though, we see that our capacity for accurate predictions is pretty

limited. Back in the early 1980s, studies were conducted to determine the likelihood

that in the future there would be a computer on every desk of an organization. The

results showed that this was very unlikely. But only a few years later, a computer on

every desk was a reality, and soon people often had not just one, but multiple

computers.

In the early 1990s, studies showed that it was highly unlikely that everyone would soon

have a cell phone. After all, the early versions were heavy and looked like sewing ma-

chines. Only a few years later, however, schools had to prevent students from using

their cell phones during lectures and exams because they were using them to exchange

results with each other. And at the same time, nobody spotted the business case for

SMS (text messages). It was mainly a leftover from development, and it simply wasn’t

removed from production. Yet, SMS hit the world, became widely used overnight, and

today is making gigantic profits for many organizations.

So are we good at making predictions and determining business cases? Obviously not.

Did someone foresee the emergence and success of Google, Skype, Facebook, and

Twitter? Was there a careful business case defined before these technologies were de-

veloped? It seems that services can become very successful even if we haven’t thought

about a business case beforehand; and in fact, had the developers tried to make a busi-

ness case for the aforementioned technologies, they may well have arrived at the con-

clusion that there wasn’t one and opted not to deploy the service.

2 | Chapter 1: The Business Case

This is how evolution works. Technology and science are an expression of the evolution

of human consciousness. And because this is a collective factor, it is highly unpredict-

able. In the 1920s, for instance, it was a huge problem that more and more people were

starting to use horses for transport. Initially, only the rich could afford traveling by

horse, but soon everyone was using them. Trend analysts predicted that mankind

would soon drown in horse dung. This was a serious concern, and nobody could think

of a useful answer to this problem. The solution came from a very unexpected angle.

It was the invention of the car, and it revolutionized not only the transportation system,

but also the whole industry. This example confirms Albert Einstein’s assertion that “no

problem can be solved from the same level of consciousness that created it.” Now we

face new problems that have emerged from the invention of the car, and just like with

the horse dung dilemma, we don’t really know how to solve them. Chances are, the

true solution will come from an unexpected evolutionary angle again.

For the car to be used widely, we needed better streets. Today we have an extended

high-level street system in large parts of the world to enable transport for all the cars

in use. Was there a business case for building all these streets? I guess nobody asked

the question in this way; otherwise, we would probably not have our current street

system.

Some creative developers designed IPv4 in the early 1970s. Their goal was to develop

a protocol to connect a handful of computers. They managed to create a protocol that

is the basic transport for our gigantic modern-day Internet (approximately 2 billion

users in 2011, growing exponentially; up from 360 million in 2001). But these devel-

opers did not have anything like the Internet in mind. There was no business plan and

no business case for the Internet. It just happened during the 1990s; the world picked

it up and started using it on a widespread scale, from online ecommerce in the

mid-1990s to today’s social networking and cloud services. And the IETF (Internet

Engineering Task Force) responded to the market demand and developed all the ex-

tensions to IPv4 that we currently use.

There was no business case for the Internet because evolution doesn’t

need a business case. Evolution just happens without asking us.

And by the way, don’t think this is the end—evolution is also never-ending. For ex-

ample, Vint Cerf, the “father of the Internet,” and one of the guys who developed IPv4

in those early days, is now working on standardizing the Interplanetary Communica-

tion protocol based on the Bundle Protocol (RFC 5050); first implementations are cur-

rently available and tests are being run. So, while we may think this sounds crazy be-

cause we’re focused on planetary issues like danger from atomic power, natural cata-

strophes, wars, and financial crisis, some visionaries are working on the future— with

no business case, but fueled by evolutionary impulses.

The Inevitable Business Case Discussion | 3

The Internet has definitely reshaped our world, changed the way we communicate,

impacted the way we approach business and education, broken down hierarchies, and

established an important ingredient for globalization. It happened because we all jum-

ped on the bandwagon, saw it as a useful tool, and started investing and participating

in building and extending it. It is a global collective collaboration.

So what is the business case for IPv6? If you want, we can put it like this:

The business case for IPv6 is the continued use and expansion of the Internet.

Without the introduction of IPv6, the Internet cannot continue to grow now that the

IPv4 address space is definitely exhausted. This means that everyone who uses and

profits from the Internet has to do his part in helping integrate IPv6. Integration too

will have to be a global collective collaboration. For some corporate cultures, this might

be a sufficient business case.

But let’s go on and analyze the business case question in detail in a more practical

context.

IPv6 Has No Immediate Business Case for Many

Corporations and organizations have maintained networks for many years. When we

started maintaining them, mostly in the early 1990s, the networks were small and few

were the tools we had available to manage them. Soon the number of network devices

and the variety of network services were growing exponentially. At the same time, the

requirements for management, administration, and security were increasing. When we

started designing our IPv4-based networks, we did not have a real understanding of

what lay ahead. But we learned while growing the networks and whenever we faced

new challenges, we finally found solutions; and when public demand became obvious,

the IETF developed all the useful extensions to the IPv4 protocol, such as DNS, DHCP,

IPSec, and NAT.

With regard to the business case, we can say that the evolution, extension, and opti-

mization of our network infrastructure always came at a cost. In other words, evolving

our network has always been part of our returning budget—costs used to maintain a

state-of-the-art infrastructure capable of running state-of-the-art services. We have to

extend our infrastructure for more bandwidth constantly, as the services running on

top continue to consume more bandwidth. We have to replace network devices in

regular cycles, and when it comes to replacing core routers, this is usually a substantial

cost factor. We also have to invest a lot into securing our networks and providing an

infrastructure that can accommodate the demands of mobile users. And we constantly

upgrade operating systems to newer versions, such as the currently ongoing migration

from Windows Server 2003 to Windows Server 2008.

Do all these investments have a business case? What is the business case in upgrading

a core router? What is the business case in upgrading a server operating system? Both

do their job—they route or run services—so why should we invest in upgrading them?

4 | Chapter 1: The Business Case

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