IPv5 发生了什么？为什么有 IPv4、IPv6 但没有 IPv5？
IPv4 IPv6 IPv5
![](/data/attachment/album/202004/30/093620td8b60tib8kwtscd.png)


如果你花过很多时间在互联网上，那么你应该已经听说过计算机每天使用的 IPv4 和 IPv6 协议。


你可能会问的一个问题是：为什么没有 IPv5？为什么 IPv6 在 IPv4 之后而不是 IPv5 之后出现？是否有 IPv5，如果是，那么 IPv5 发生了什么？


答案是肯定的，曾经有一个 IPv5。让我解释一下这里发生的事。


### 互联网的早期历史


![ARPA Logical Map in 1977 | Image courtesy: Wikipedia](/data/attachment/album/202004/30/093657hffmkfva14zfiudv.png)


在 1960 年代后期，美国国防部的[高级研究计划局](https://en.wikipedia.org/wiki/DARPA)（DARPA）发起了一个[项目](https://en.wikipedia.org/wiki/ARPANET)来连接全国的计算机。最初的目标是创建一个由全国 ARPA 资助的所有计算机组成的网络系统。


由于这是第一次将如此规模的网络整合在一起，因此他们也在不断发展自己的技术和硬件。他们首先做的工作之一就是开发名为<ruby> <a href="https://en.wikipedia.org/wiki/Transmission_Control_Protocol">  传输控制协议 </a> <rt>  Transmission Control Protocol </rt></ruby>（TCP）的<ruby> 互联网协议 <rt>  Internet Protocol </rt></ruby>（IP）。该协议“可靠、有序，并会对运行于通过 IP 网络传输的主机上的应用的八进制（字节）流通讯进行错误检测”。简单来说，它可以确保数据安全到达。


最初，TCP 被设计为[“主机级别的端到端协议以及封装和路由协议”](https://fcw.com/articles/2006/07/31/what-ever-happened-to-ipv5.aspx)。但是，他们意识到他们需要拆分协议以使其更易于管理。于是决定由 IP 协议处理封装和路由。


那时，TCP 已经经历了三个版本，因此新协议被称为 IPv4。


### IPv5 的诞生


IPv5 开始时有个不同的名字：<ruby> 互联网流协议 <rt>  Internet Stream Protocol </rt></ruby>（ST）。它是[由 Apple、NeXT 和 Sun Microsystems](https://www.lifewire.com/what-happened-to-ipv5-3971327) 为试验流式语音和视频而创建的。


该新协议能够“在保持通信的同时，以特定频率传输数据包”。


### 那么 IPv5 发生了什么？


IPv5 从未被接受为正式的互联网协议。这主要是由于 32 位限制。


IPV5 使用与 IPv4 相同的寻址系统。每个地址由 0 到 255 之间的四组数字组成。这将可能的地址数量限制为 [43 亿](https://www.lifewire.com/what-happened-to-ipv5-3971327)个。


在 1970 年代初，这似乎比全世界所需要的还要多。但是，互联网的爆炸性增长证明了这一想法是错误的。2011 年，世界上的IPv4地址正式用完了。


在 1990 年代，一个新项目开始致力于研究下一代互联网协议（IPng）。这形成了 128 位的 IPv6。IPv6 地址包含 [“8 组 4 字符的十六进制数字”](https://www.lifewire.com/what-happened-to-ipv5-3971327)，它可以包含从 0 到 9 的数字和从 A 到 F 的字母。与 IPv4 不同，IPv6 拥有数万亿个可能的地址，因此我们应该能安全一阵子。


同时，IPv5 奠定了 VoIP 的基础，而该技术已被我们用于当今世界范围内的通信。**因此，我想在某种程度上，你可以说 IPv5 仍然可以保留到了今天**。


希望你喜欢有关互联网历史的轶事。你可以阅读其他[关于 Linux 和技术的琐事文章](https://itsfoss.com/category/story/)。


如果你觉得这篇文章有趣，请花一点时间在社交媒体、Hacker News 或 [Reddit](https://reddit.com/r/linuxusersgroup) 上分享它。




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via: <https://itsfoss.com/what-happened-to-ipv5/>


作者：[John Paul](https://itsfoss.com/author/john/) 选题：[lujun9972](https://github.com/lujun9972) 译者：[geekpi](https://github.com/geekpi) 校对：[wxy](https://github.com/wxy)


本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出


OK
![Warp Terminal](/assets/images/warp-terminal.webp)


![Warp Terminal](/assets/images/warp-terminal.webp)

If you have spent any amount of time in the world of the internet, you should have heard about the IPv4 and IPv6 protocols that our computers use every day.

One question that you might be asking is: Why there is no IPv5? Why IPv6 came after IPv4 and not IPv5? Was there ever a IPv5 and if yes, whatever happened to IPv5?

The answer is yes, there was an IPv5…sort of. Let me quickly explain a few things around it.

## The early history of the internet

![Arpa Internet](https://itsfoss.com/content/images/wordpress/2020/04/Arpa_internet.png?fit=800%2C573&ssl=1)

[Wikipedia](https://en.wikipedia.org/wiki/ARPANET)

In the late 1960s, the US Department of Defense’s [Advanced Research Projects Agency](https://en.wikipedia.org/wiki/DARPA) (ARPA) started a [project](https://en.wikipedia.org/wiki/ARPANET) to link computers across the country. The initial goal was to create a networked system of all of the ARPA-funded computers across the country.

Since this was the first time a network of this scale was put together, they were also creating the technology and hardware as they went. One of the first things they worked was an internet protocol (IP) named [Transmission Control Protocol](https://en.wikipedia.org/wiki/Transmission_Control_Protocol) (TCP). This protocol “reliable, ordered, and error-checked delivery of a stream of octets (bytes) between applications running on hosts communicating via an IP network”. Basically, it made sure data got where it needed to go safely.

Originally, TCP was designed to be [“a host-level, end-to-end protocol and a packaging and routing protocol”](https://fcw.com/articles/2006/07/31/what-ever-happened-to-ipv5.aspx). However, they realized that they needed to split the protocol to make it more manageable. It was decided that IP would handle packaging and routing.

By this time TCP had gone through three versions, so the new protocol became known as IPv4.

## The birth of IPv5

IPv5 started life under a different name: Internet Stream Protocol (or ST). It was created to experiment with streaming voice and video [“by Apple, NeXT, and Sun Microsystems”](https://www.lifewire.com/what-happened-to-ipv5-3971327).

This new protocol was capable of “transferring data packets on specific frequencies while maintaining communication”.

## So what happened to IPv5?

![What Happened To Ipv5](https://itsfoss.com/content/images/wordpress/2020/04/what-happened-to-ipv5.png)

IPv5 was never accepted as an official internet protocol. This was mainly due to the 32-bit limitation.

IPV5 used the same addressing system as IPv4. Each address was made up of four sets of numbers between 0 and 255. This limited the number of possible addresses to [4.3 billion](https://www.lifewire.com/what-happened-to-ipv5-3971327).

In the early 1970s, that might have seemed like more than the world would ever need. However, the explosive growth of the Internet proved that idea wrong. In 2011, the world officially ran out of the IPv4 addresses.

In the 1990s, a new project was started to work on the next generation of internet protocol (IPng). This led to the 128-bit IPv6. An IPv6 address contains a [“series of eight 4-character hexadecimal numbers”](https://www.lifewire.com/what-happened-to-ipv5-3971327) that can contain numbers from 0 to 9 and letters from A to F. Unlike IPv4, IPv6 had trillions of possible addresses, so we should be safe for a while.

Meanwhile, IPv5 laid the groundwork for the voice-over-IP technology that we use to communicate all over the world today. **So, I guess in some small way, you could say that IPv5 still survives to this day**.

I hope you liked this anecdote about internet history. You may read some other [trivia article about Linux and tech in general](https://itsfoss.com/category/story/).

If you found this article interesting, please take a minute to share it on social media, Hacker News or [Reddit](http://reddit.com/r/linuxusersgroup).