This chapter covers the following topics, which you need to understand to pass the CCNP/CCDP/CCIP BSCI exam:
Criteria in designing IP networks
Private addresses on the Internet
Connecting to the outside world with NAT
This chapter deals with designing IP networks to efficiently use the addressing structure to reduce the routing tables and thus conserve network resources.
Many of the design principles for an IP network were dealt with in Chapter 2, "IP Addressing." The approach in Chapter 2 was a practical one, explaining how to address a network and the need for a hierarchical design. By contrast, this chapter examines the design criteria from a high-level perspective. Instead of describing how you would design a hierarchical addressing scheme to support variable-length subnet masks (VLSM) and allow summarization, this chapter explains why there is a need for hierarchical structure and summarization.
This chapter also considers the relatively recent solution to the problem of applying for limited Internet addresses from the IANA, private addressing. When using private addresses, any connection to the Internet must be handled in such a way that duplicate addresses do not appear in the public domain. Duplicate addresses result in a lack of connectivity. Solutions to the problem of duplicate addressing are explored within this chapter.
IPv6 and its features are discussed in terms of network design and implementation. In particular, the advantages of IPv6 over IPv4 are considered . The IPv6 addressing format is also explained, as are the various methods of transitioning an IPv4 network to run IPv6 and the routing protocols that are available for the new IP stack.