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Extending IP Addresses
Design Considerations for Route Summarization
Keep the following information in mind when designing your network sum-
marization points:
Only classless routing protocols support route summarization. Exam-
ples of classless routing protocols include RIPv2, EIGRP, and OSPF.
Therefore, if you are working in a RIPv1 or IGRP environment, route
summarization is not going to work for you.
Classless and classful protocols were discussed in Chapter 2, "Routing
Route summarization is most effective when the addresses have been
organized in a hierarchy (i.e., "hierarchical addressing"). When we
speak of addresses being hierarchical, we mean that the IP subnets at
the "bottom of the tree" (i.e., the ones with the longest subnet masks)
are subsets of the subnets at the "top of the tree" (i.e., the ones with
the shortest subnet masks). Figure 3.6 will be used to illustrate hierar-
chical versus non-hierarchical addressing.
Copyright ©2001 SYBEX , Inc., Alameda, CA