计算机网络子网划分_子网划分和超网| 计算机网络

计算机网络子网划分

1)子网划分 (1) Subnetting)

Subnetting is a concept of diving a block of addresses into sub-blocks of addresses. During the era of classful addressing (as it’s obscured now), subnetting was introduced. Say, an organization is granted a large block in class A or B, it can divide the address block assigned into several contiguous groups (sub-blocks) and assign each group to smaller networks (subnets).

子网划分是将地址块分成地址子块的概念。在分类寻址时代(现在已经模糊)，引入了子网划分。假设组织被授予A或B类中的一个大块，它可以将分配的地址块划分为几个连续的组(子块)，并将每个组分配给较小的网络(子网)。

2)超网 (2) Supernetting)

The biggest drawback of classful addressing is address depletion. The issue came in front when most of class A and class B addresses were depleted and there was still a huge demand for midsize blocks. Class C was too small to adjust and solve the situation as the size of a class C block with a maximum number of 256 addresses hardly satisfied the needs of most organizations.

分类寻址的最大缺点是地址耗尽。当大多数A类和B类地址用尽并且对中型块的需求仍然很大时，问题就摆在了前面。 C类太小，无法调整和解决这种情况，因为具有最多256个地址的C类块的大小很难满足大多数组织的需求。

Even a midsize organization needed more address range. The solution was supernetting.

即使是中型组织也需要更大的地址范围。解决方案是超网。

In supernetting, an organization can combine several class C blocks to create a larger block of addresses. Several networks were combined to create a supernetwork. An organization can apply for a set of class C blocks (i.e. multiple class of C blocks) instead of just one. For example, an organization that needs 500 addresses can be granted three contiguous class C blocks. Then, an organization can use such addresses to create one supernetwork.

在超网中，组织可以组合多个C类块来创建更大的地址块。几个网络被合并以创建一个超级网络。一个组织可以申请一组C类块(即多个C类块)，而不是一个。例如，一个需要500个地址的组织可以被授予三个连续的C类块。然后，组织可以使用此类地址创建一个超级网络。

Classless addressing actually eliminated the need for supernetting.

实际上，无类寻址消除了对超网的需要。