Requirements for Route Summarization

To create route summarization, there are some necessary requirements:

  • Routers need to be running a classless routing protocol, as they carry subnet mask information with them in routing updates. (Examples are RIP v2, OSPF, EIGRP, IS-IS, and BGP.)

  • Addresses need to be assigned in a hierarchical fashion for the summarized address to have the same high-order bits. It does us no good if Winnipeg has network and while resides in Calgary and is assigned in Edmonton. No summarization could take place from the edge routers to Vancouver.


Because most networks use NAT and the 10 network internally, it is important when creating your network design that you assign network subnets in a way that they can be easily summarized. A little more planning now can save you a lot of grief later.

CCNA Self-Study(c) CCNA Portable Command Guide
CCNA Portable Command Guide
ISBN: 1587201585
EAN: 2147483647
Year: 2006
Pages: 261
Authors: Scott Empson

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