Filter list - using as-path access list
ip as-path access-list 1 permit 3561
ip as-path access-list 2 deny 35
ip as-path access-list 2 permit .*
neighbor 171.69.233.33 remote-as 33
neighbor 171.69.233.33 filter-list 1 in
neighbor 171.69.233.33 filter-list 2 out
Listen to routes from AS 3561. Implicit deny everything else inbound.
Don’t announce routes from AS 35, but announce everything else (outbound).