A router has two paths to reach another network in a different autonomous system. Neither route
was generated by the local router and both routes have the same default weight and local
preference values. Which statement is true about how BGP would select the best path?
A.
If the command bgp always-compare-med has been given, then the router will prefer the route
with the highest MED.
B.
The router will prefer the route with the lower MED.
C.
The router will prefer the shortest autonomous system path.
D.
To influence one route to be preferred, its default local preference value will be changed via the
use of the command bgp default local-preference 50.
Explanation:
In the Route selection decision process, if the weight, local preference & route originated are the
same then the shortest AS path will be chosen.
The full Route selection decision process is listed below:
1. Prefer highest weight (local to router)2. Prefer highest local preference (global within AS)3.
Prefer route originated by the local router (next hop = 0.0.0.0)4. Prefer shortest AS path5. Prefer
lowest origin code (IGP < EGP )6. Prefer lowest MED (exchanged between autonomous
systems)7. Prefer EBGP path over IBGP path8. Prefer the path through the closest IGP neighbor
(IGP cost)9. Prefer oldest route for EBGP paths10. Prefer the path with the lowest neighbor BGP
router ID11. Prefer the path with the lowest neighbor IP address
Reference:
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml