Case Study: VLSMs
In 1987, RFC 1009 was published with the purpose of specifying how a subnetted network could use more than one subnet mask. As discussed earlier in this chapter, when an IP network is assigned more than one subnet mask, it is considered a network with variable-length subnet masks because the subnet masks (prefixes) have varying lengths.
If you recall, the use of VLSM brings benefits to a network and routing that allow for increased routing optimization in the form of a smaller and more concise routing table, known as route aggregation, as well as more efficient use of an organization’s assigned IP address space.
A /16 network with a /22 extended-network prefix permits 64 subnets (26), each of which supports a maximum of 1022 ...
Get OSPF Network Design Solutions, Second Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
