networking - 选择 172.16/192.168 背后的原因？

Question

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9年前关闭。




众所周知，有三个 IPv4 地址 block 被选择为专用网络保留:

 10.0.0.0        -   10.255.255.255  (10/8 prefix)
 172.16.0.0      -   172.31.255.255  (172.16/12 prefix)
 192.168.0.0     -   192.168.255.255 (192.168/16 prefix)

(由 RFC 1918 指定)。但是，虽然我可以理解为什么 10.0.0.0 会是一个自然选择，但我想不出为什么在所有可能性中选择 172.16.0.0 和 192.168.0.0 的具体原因。我试图用谷歌搜索，但什么也没得到，RFC 文档也没有提供任何解释。这真的只是一个随机的决定吗？

Answer 1

正如 ganeshh.iyer 所说“

10.0.0.0/8 was the old ARPANET, which they picked up on 01-Jan-1983. When they shut down the ARPANET in 1990, the 10.0.0.0/8 block was freed. There was much argument about if there should ever be private IP spaces, given that a goal of IPv4 was universal to all hosts on the net.

In then end, practicality won out, and RFC 1597 reserved the now well known private address spaces. When ARPANET went away, the 10.0.0.0/8 allocation was marked as reserved and since it was known that the ARPANET was truly gone (the hosts being moved to MILNET, NSFNET or the Internet) it was decided that this was the best Class A block to allocate.

Note Class A. This was before CIDR. So, the Class A, B and C private address netblocks needed to come out of the correct IP ranges.

I know that 172.16.0.0/12 was picked because it offered the most continuous block of Class B (/16) addresses in the IP space that was in a reserved block. 192.0.0.0/24 was always reserved for the same reason that 0.0.0.0/8 and 128.0.0.0/16 were reserved (first blocks of the old Class C, A and B network blocks) so assigning 192.168.0.0/24 out as private fit well -- 192.0.2.0/24 was already TEST-NET, where you could use them in public documentation without fear of someone trying it (see example.com for another example.)"

引用自:

https://supportforums.cisco.com/thread/2014967

https://supportforums.cisco.com/people/ganeshh.iyer