Users Guide

BGP 1407
decision process applies outbound policy to routes in the local RIB and
determines the status of aggregate routes. Active aggregates and individual
routes that pass outbound policy are placed in an Adj-RIB-Out specific to
each update group, and UPDATE messages are sent to communicate the
routes to neighbors.
Figure 38-1. BGP Decision Process
BGP Route Selection
Dell EMC Networking BGP uses the following route selection rules in order
from 1 to N:
1 Prefer the route with the higher local preference
2 Prefer a locally-originated route over a non-locally originated route
3 Prefer the route with the shorter AS Path
4 Prefer the route with the lower ORIGIN. IGP is better than EGP is better
than INCOMPLETE.
Update
Update
RX
Adj-
RIB-In
DEC PROC P1
(inbound policy,
calc local pref)
Accept-
RIB-In
Loc-RIB
Adj-RIB
Out
Adj-RIB-
Out
Adj-RIB-
Out
Update
DEC PROC P3
(outbound policy,
incl. aggregation)
RTO
Pass redist
Policy?
Network
routes
DEC
PROC P2
(best route
selection)
Best route
changes
yes
Next-hop
resolution