net186-config/lib/10-community-transit.conf

function pub_add_communities(int ASN; int PeerType) {
    # DIRECT PEER
    if (PeerType=0) then {
        if bgp_large_community !~ [(LOCAL_ASN, 110, *)] then {
            bgp_large_community.add((LOCAL_ASN, 110, 0));
            bgp_large_community.add((LOCAL_ASN, 110, 2));
        }

    # PEER via IX
    } else if (PeerType=1) then {
        if bgp_large_community !~ [(LOCAL_ASN, 110, *)] then {
            bgp_large_community.add((LOCAL_ASN, 110, 0));
            bgp_large_community.add((LOCAL_ASN, 110, 1));
        }
        

    # UPSTREAM
    }else if (PeerType=10) then {
        if bgp_large_community !~ [(LOCAL_ASN, 110, *)] then bgp_large_community.add((LOCAL_ASN, 110, 10));

    # DOWNSTREAM
    } else if (PeerType=20) then {
        if bgp_large_community !~ [(LOCAL_ASN, 110, *)] then bgp_large_community.add((LOCAL_ASN, 110, 20));
    # Self Route
    } else if (PeerType=30) then {
        if bgp_large_community !~ [(LOCAL_ASN, 110, *)] then bgp_large_community.add((LOCAL_ASN, 110, 30));
    }

    # Finished (LOCAL_ASN, 110, *);

    if bgp_large_community !~ [(LOCAL_ASN, 120, *)] then bgp_large_community.add((LOCAL_ASN, 120, POP));
    if bgp_large_community !~ [(LOCAL_ASN, 121, *)] then bgp_large_community.add((LOCAL_ASN, 121, REGION));
    
    # Finished (LOCAL_ASN, 120~130, *);
    return true;
}

function pub_preprocess_communities() {
    if (LOCAL_ASN, 115, 1) ~ bgp_large_community then bgp_path.prepend(LOCAL_ASN);
    if (LOCAL_ASN, 115, 3) ~ bgp_large_community then {
        bgp_path.prepend(LOCAL_ASN);
        bgp_path.prepend(LOCAL_ASN);
        bgp_path.prepend(LOCAL_ASN);
    }
    if (LOCAL_ASN, 115, 5) ~ bgp_large_community then {
        bgp_path.prepend(LOCAL_ASN);
        bgp_path.prepend(LOCAL_ASN);
        bgp_path.prepend(LOCAL_ASN);
        bgp_path.prepend(LOCAL_ASN);
        bgp_path.prepend(LOCAL_ASN);
    }
    # Finished (LOCAL_ASN, 115, *);
    return true;
}

function pub_process_communities(int ASN; int PeerType) {
    if (65535, 65281) ~ bgp_community then return false;
    if (65535, 65282) ~ bgp_community then return false;
    if (65535, 65283) ~ bgp_community then return false;
    
    if (LOCAL_ASN, 2, ASN) ~ bgp_large_community then return false;

    # PEER
    if (PeerType<10) then {
        if (LOCAL_ASN, 1, 1) ~ bgp_large_community then bgp_community.add((65535, 65281));

    # UPSTREAM
    } else if (PeerType=10) then {
        if (LOCAL_ASN, 1, 0) ~ bgp_large_community then return false;

    # DOWNSTREAM
    } else if (PeerType=20) then {
        if (LOCAL_ASN, 1, 2) ~ bgp_large_community then return false;
    }
    return true;
}

function pub_process_path() {
    # Delete Self eBGP Confed Path.
    bgp_path.delete([4200000000..4225479999]);

    # Self PoP
    if (LOCAL_ASN, 120, POP) ~ bgp_large_community then {
        # Nothing here.
    } else {
        # Route is via or locate Europe & Africa & Middle East
        if bgp_large_community ~ [(LOCAL_ASN, 122, 100), (LOCAL_ASN, 122, 300..310), (LOCAL_ASN, 122, 600), (LOCAL_ASN, 121, 100), (LOCAL_ASN, 121, 300..310), (LOCAL_ASN, 121, 600)] then bgp_path.prepend(LOCAL_ASN);
        # Route is via or locate America
        if bgp_large_community ~ [(LOCAL_ASN, 122, 200..299), (LOCAL_ASN, 121, 200..299)] then bgp_path.prepend(LOCAL_ASN);
        # Route is via or locate East Asia & Oceania
        if bgp_large_community ~ [(LOCAL_ASN, 122, 400..500), (LOCAL_ASN, 121, 400..500)] then bgp_path.prepend(LOCAL_ASN);
    }

    pub_preprocess_communities();
}

function transit_import_filter(int ASN) {
    if !is_valid() then return false;
    pub_add_communities(ASN, 10);
    pub_preprocess_communities();
    bgp_local_pref = 400 - bgp_path.len * 10;
    if LOCAL_ASN ~ bgp_path then bgp_local_pref = 1;
    pub_route_controller_specific();
    return true;
}

function transit_export_filter(int ASN) {
    pub_process_path();
    if !is_valid() then return false;
    if bgp_large_community ~ [(LOCAL_ASN, 110, 0), (LOCAL_ASN, 110, 10)] then return false;
    if !pub_is_downstream_route() && source = RTS_BGP then {
        print "transit exporter: for ", net, " ASN ", bgp_path.last;
        return false;
    }
    pub_add_communities(ASN, 30);
    if pub_process_communities(ASN, 10) then return true;
    else return false;
}