Discontiguous Networks, Subnet 0, and Summarization Using IGRP

During the process of researching the material for this section, an anomaly was discovered in the behavior of IGRP. IGRP would install a summarized route for a major network when the router had a connection to a subnet of the same major net—which is not supposed to happen. Cisco engineers discovered this behavior while reviewing the material for this book prior to publication.

The Cisco engineers opened a bug against it—CSCdj03421— and fixed the bug so that IGRP now behaves as expected. In other words, it behaves now exactly as in the previous section on RIP. This bug has been integrated in IOS versions 11.0, 11.1 (and all 11.1-based releases), 11.2 (and all 11.2-based releases), ...

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