Cisco Cisco IOS Software Release 12.4(15)T

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This document describes the Open Shortest Path First (OSPF) mechanism to exclude IP prefixes of 
connected networks from link-state advertisements (LSAs). When OSPF is deployed in large networks, 
limiting the number of IP prefixes that are carried in the OSPF LSAs can speed up OSPF convergence.

This feature can also be utilized to enhance the security of an OSPF network by allowing the network 
administrator to prevent IP routing toward internal nodes.

Your Cisco IOS software release may not support all of the features documented in this module. To reach 
links to specific feature documentation in this module and to see a list of the releases in which each feature is 
supported, use the 

.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS 
software image support. To access Cisco Feature Navigator, go to 

. An 

account on Cisco.com is not required.