Policies for BGP Route Selection

Created Apr 09, 2016 17:14:55Latest reply Apr 10, 2016 00:13:59 914 1 0 0
Policies for BGP Route Selection
  • x
  • convention:

gennady_fedonov     Created Apr 10, 2016 00:13:59 Helpful(0) Helpful(0)

When there are multiple routes to the same destination, BGP selects routes according to the following policies:
1. BGP prefers the route with the largest PreVal.
2. BGP prefers the route with the highest Local_Pref.
3. BGP prefers the aggregated route. The preference of an aggregated route is higher than that of a non-aggregated route.
4. BGP prefers the local route that is manually aggregated. The preference of the local route that is manually aggregated is higher than that of the local route that is automatically aggregated.
5. BGP prefers the local route that is imported by using the network command. The preference of the route that is imported by using the network command is higher than that of the local route that is imported by using the import-route command.
6. BGP prefers the route with the shortest AS_Path.
7. BGP compares Origin attributes, and selects routes whose origin types are IGP, EGP, and Incomplete in sequence.
8. BGP prefers the route with the smallest MED.
9. BGP prefers the routes learned from EBGP. The preference of an EBGP route is higher than that of an IBPG route.
10. BGP prefers the route of an IGP with the smallest metric in an AS. If load balancing is configured and there are multiple external routes with the same AS_Path, load balancing is performed according to the number of configured routes.
11. BGP prefers the route with the shortest Cluster_List.
12. BGP prefers the route with the smallest Originator_ID.
13. BGP prefers the route advertised by the router with the smallest router ID.
14. BGP compares IP addresses of its peers, and prefers the route that is learnt from the peer with a smaller IP address.
  • x
  • convention:

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