Juniper BGP Config Example for Customers, Transit and Peers

(taken from: http://puck.nether.net/bgp/juniper-config.html )

Due to the ease of configuring bgp, it is easy to leave out critical steps that will result in some unintended consequences. There are a number of cases that exist persistently in the routing tables where some small network is actually connecting two “larger” networks together for some routes/prefixes for various reasons.

As a result of this, and the ease of these errors/mistakes, we wanted to provide a few simple examples that would ease most networks configuration needs and provide a common reference.

These examples cover a few basic bgp related topics, including:

• import and export policy uses
• prefix-lists
• example uses of communities
• local-preference

- UNDER CONSTRUCTION.

protocols {
    bgp {
        group eBGP-to-customer {
            type external;
            metric-out igp;
            export [ customer-out ];
            remove-private;
            neighbor 1.2.3.4 {
                description "Customer AS267";
                out-delay 1;
                import [ customer-in AS267-in ];
                peer-as 267;
            }               
        }
   }
}

policy-options {
    policy-statement customer-in {
        term default {
            then {
                local-preference 220;
                next policy;
            }
        }
    }
    policy-statement peer-in {
        term default {
            then {
                community set comm-peer;
                local-preference 200;
                next policy;
            }
        }
    }
    policy-statement transit-in {
        term default {
            then {
                community set comm-transit;
                local-preference 180;
                next policy;
            }
        }
    }

    policy-statement customer-out {
        term customer-routes {
            from community [ comm-customer comm-peer comm-transit ];
            then accept;
        }
    }

    policy-statement peer-out {
        term peer-routes {
            from community [ comm-customer ];
            then accept;
        }
    }

    policy-statement transit-out {
        term peer-routes {
            from community [ comm-customer ];
            then accept;
        }
    }


    policy-statement AS267-in {
        term match-exact {
            from {
                route-filter 0/0 exact reject;
                route-filter 204.42.252.0/22 exact;
            }
            then {
                community add comm-customer;
                next policy;
            }
        }
        then reject;
    }
    community comm-customer members XXX:220;
    community comm-peer members XXX:200;
    community comm-transit members XXX:180
}