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| 9.7 |  | The BGP Decision Process |
| 9.7.1 |  | The BGP decision process |

BGP bases its decision process on the attribute values. When faced with multiple routes to the same destination, BGP chooses the best route for routing traffic toward the destination. The following process summarizes how BGP chooses the best route:

1. If the next hop is inaccessible, the route is ignored. This is why it is important to have an IGP route to the next hop.
2. The BGP router will prefer the path with the largest weight. Weight is a Cisco proprietary parameter.
3. If the weights are the same, the BGP router will prefer the route with the largest local preference.
4. If the routes have the same local preference, the BGP router will prefer the route that was locally originated by this router.
5. If the local preference is the same, the BGP router will prefer the route with the shortest AS_Path.
6. If the AS_Path length is the same, the BGP router will prefer the route with the lowest origin type. This is when IGP is lower than EGP and EGP is lower than Incomplete.
7. If the origin type is the same, the BGP router will prefer the route with the lowest MED.
8. If the routes have the same MED, the BGP router will prefer the route in the following manner. External (EBGP) is better than confederation external, which is better than IBGP. BGP confederations are not covered in this course. For more information, consult Cisco's web site, at http://www.cisco.com/univercd/home/home.htm.
9. If all the preceding scenarios are identical, the BGP router will prefer the route that can be reached by way of the closest IGP neighbor. That means taking the shortest internal path inside the AS to reach the destination by following the shortest path to the BGP Next Hop.
10. If the internal path is the same, the BGP router ID will be a tiebreaker. The BGP router will prefer the route coming from the BGP router with the lowest router ID. The router ID is usually the highest IP address on the router or the loopback address.

| Web Links Configuring BGP http://www.cisco.com/univercd/cc/td/doc/product/ software/ios122/122cgcr/fipr_c/ipcprt2/1cfbgp.htm