Summary

• The BGP local preference attribute can be changed to manipulate the best-path decision process, either for all routes or for selected routes using route maps.

- Higher local preference values are preferred.

- Local preference is used only between IBGP speakers within the same AS.

• The MED values can be changed to manipulate packets returning to an AS, either for all routes or for selected routes, using route maps.

- Lower MED values are preferred.

- The MED is sent to EBGP neighbors; those routers propagate the MED within their AS. The routers within the AS use the MED but do not pass it on to the next AS.

• Routers in a typical enterprise BGP implementation multihome to two ISPs and pass default routes to other routers within the enterprise.

6-118 Building Scalable Cisco Internetworks (BSCI) v3.0 © 2006 Cisco Systems, Inc.

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