BGP: receiving routes


the routes you receive and accept from another AS influence what traffic is send there

where you want to send traffic is a matter of policy
optimize for cost
optimize for quality
accept only certain routes (belonging to that AS)

BGP implementations have complex filters to allow you to exactly define what to accept and what routes to prefer.

allow from 178.255.1.202 prefix 192.0.2.0/23 set localpref 180
allow from 195.245.114.1 prefixlen 8 - 24 set localpref 130
allow from group "BGP-Peers" set nexthop self
deny from any prefix 0.0.0.0/0 prefixlen <= 7