Secondary IP Addressing

Most networks today make use of either routers with VLAN trunks or Layer 3 switches. This next topic moves to an interesting, but frankly less commonly used, feature that helps overcome some growing pains with an IP network.

Imagine that you planned your IP addressing scheme for a network. Later, a particular subnet grows, and you have used all the valid IP addresses in the subnet. What should you do? Three main options exist:

Image Make the existing subnet larger, by choosing a mask with more host bits. Existing hosts have to change their subnet mask settings, and new hosts can use IP addresses from the expanded address range. ...

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