Juniper bgp config

Juniper BGP Config Example for Customers, Transit and Peers

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
}