如何将网络划分为十一个子网答案

【问题标题】：How to divide a network into eleven subnets如何将网络划分为十一个子网
【发布时间】：2013-10-12 01:33:29
【问题描述】：

假设我有 136.181.0.0 /16，我想把它分成十一个子网

我得到了 /19？首先是 /16，它只有 1 个子网（实际上在没有应用子网划分时，它仍然称为网络地址）。从主机位借 1 位，您将获得 /17 和两个子网。再借一个，您将获得 4 个子网和前缀 18。再借一点，您将获得 8 个以 /19 作为 CIDR 的子网。

不确定这里的 9 日、10 日和 11 日..

1st 136.181.0.0/19 
2nd 136.181.32.0/19 
3rd 136.181.64.0/19 
4th 136.181.96.0/19 
5th 136.181.128.0/19 
6th 136.181.160.0/19 
7th 136.181.192.0/19 
8th 136.181.224.0/19 
9th 136.181.224.1/19 
10th 136.181.224.33/19 
11th 136.181.224.65/19

【问题讨论】：

对 SO 来说不是问题。试试Server Fault

标签： ip subnet divide

【解决方案1】：

136.181.0.0/16  (255.255.0.0)

(N = Network, S = Subnet, H = Host)

10001000.10110101.00000000.00000000 
NNNNNNNN.NNNNNNNN.HHHHHHHH.HHHHHHHH
NNNNNNNN.NNNNNNNN.SSSSHHHH.HHHHHHHH

01: 136.181.00000000.00000000/19 (136.181.0.0)
02: 136.181.00010000.00000000/19 (136.181.16.0)    
03: 136.181.00100000.00000000/19 (136.181.32.0)
04: 136.181.00110000.00000000/19 (136.181.48.0)
05: 136.181.01000000.00000000/19 (136.181.64.0)
06: 136.181.01010000.00000000/19 (136.181.80.0)
07: 136.181.01100000.00000000/19 (136.181.96.0)
08: 136.181.01110000.00000000/19 (136.181.112.0)
09: 136.181.10000000.00000000/19 (136.181.128.0)
10: 136.181.10010000.00000000/19 (136.181.144.0)
11: 136.181.10100000.00000000/19 (136.181.160.0)
12: 136.181.10110000.00000000/19 (136.181.176.0)
13: 136.181.11000000.00000000/19 (136.181.192.0)
14: 136.181.11010000.00000000/19 (136.181.208.0)
15: 136.181.11100000.00000000/19 (136.181.224.0)
16: 136.181.11110000.00000000/19 (136.181.240.0)

您需要 11 个子网，因此需要 4 个子网位来创建 16 (2^4) 个子网和 4094 (2^12-2) 个可用主机地址。

【讨论】：

如果不是20，19只能创建8个子网。
@RahulKadukar，我们至少需要 11 个子网，而 /20 只为您提供 8 subnets。所以我们需要使用/19来得到16 subnets，这符合11个子网的要求。
136.181.0.0/19 实际上是 136.181.0.0 到 136.181.31.255 而不是 136.181.0.0 到 136.181.15.255 正如你所期望的

【解决方案2】：

As we require 11 subnets, we require 4 bits from the host side into the network side.

Number of bits on the network side is 20.

01: 136.181.00000000.00000000/20 (136.181.0.0) 
02: 136.181.00010000.00000000/20 (136.181.16.0)    
03: 136.181.00100000.00000000/20 (136.181.32.0)
04: 136.181.00110000.00000000/20 (136.181.48.0)
05: 136.181.01000000.00000000/20 (136.181.64.0)
06: 136.181.01010000.00000000/20 (136.181.80.0)
07: 136.181.01100000.00000000/20 (136.181.96.0)
08: 136.181.01110000.00000000/20 (136.181.112.0)
09: 136.181.10000000.00000000/20 (136.181.128.0)
10: 136.181.10010000.00000000/20 (136.181.144.0)
11: 136.181.10100000.00000000/20 (136.181.160.0)

Wasted IP Address = 5 * 2^12.

【讨论】：