As mentioned in Chapter 1, route summarization (also called aggregation) is the consolidation of multiple, contiguous routes into a single generalized route. It is recommended that you use summarization whenever you can, as your network addressing allows, to promote efficient and stable routing. If you are deploying a network from scratch, definitely plan your addressing so you can leverage summarization.
Summarization typically applies to classless routing protocols such as EIGRP and OSPF. RTP and IGRP are more primitive and do not have the summarization capabilities covered in this chapter.
NOTE BGP is a popular exterior routing protocol with rich summarization capabilities. Consult the Bibliography for sources of BGP information. Additionally, a good BGP primer is freely available at http://www.cisco.com/univercd/cc/td/doc/cisintwk/ics/index.htm on Cisco's Web site. The primer can also be found by searching the Cisco Web site for internetworking case studies.
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