Cisco IT standards for IP addressing within the enterprise are required to manage the limited and sometimes inflexible resource of available IP address blocks. Cisco IT global network engineers have learned to make IP address planning a required part of planning any new service. Public address space is conserved as much as possible, and private addresses are used in a variety of services whenever it makes sense.

This best practices describes the Cisco IT standards for IP addressing, including how and where and why private and public addressing is used. It also describes some of the priorities and policies related to allocating address blocks within a network, and managing address resources within the enterprise.

Benefits of effective IP address management and deployment include:

  • Conservation of scarce resources, which can also help in justifying requests for more address space by national or local Internet registries
  • Enabling more efficient and faster hierarchical routing, consuming less router memory