
IP Concepts, Terminology, and Features
1-13
Using selection criteria encoded in the route weight, IP chooses routes in the
following order:
• The route with the highest preference value (see “Route Preferences” on
page 1-11)
• A direct or OSPF intra-area route with the lowest metric
• A direct route with the lowest metric
• An OSPF intra-area route with the lowest metric
• An OSPF interarea route with the lowest metric
• An OSPF Type 1 external route with the lowest metric
• A BGP route with the highest LOCAL_PREF value
• A RIP route with the lowest metric
• An EGP route with the lowest metric
• A static route with the lowest metric
• An OSPF Type 2 external route with a pre-Version-8.00-style metric
Note: Beginning with Version 8.00, a direct route (interface) that is part of an
OSPF area is not automatically chosen over an OSPF intra-area route. As a
result, it is possible to configure a slow direct link (for example, a backup
dialup line) with a high metric value (wfIpInterfaceCost) and route packets to
a fast link on another router in the same OSPF area. Direct routes that are not
included in an OSPF area are assumed to have a metric of 0 and are always
chosen over other routes.
Note: If OSPF is configured to propagate external routes using the route
weight as the Type 2 metric, routes that are received as OSPF ASE Type 2
routes are evaluated according to their respective origins (for example, RIP or
BGP).
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