no synchronization

no synchronization
The information covered in this section should give you a good understanding of how BGP
synchronization occurs. In the next section, we will take a look at the use of route aggregation
in BGP.
Synchronization with a partial mesh is not a substitute for running iBGP on all
routers in the AS and configuring a full mesh with no synchronization, because
black holes are still likely to develop due to a discrepancy between BGP-learned
routes and IGP-learned routes. Just because the AS will not advertise these black
holes to neighboring ASs does not mean that their existence is not a problem.
FIGURE 8 . 1 1 BGP synchronization
AS100
AS 200
AS 300
R1 R5
R2 R4
R3