BPG inbound filtering based on origin as-path and communities - configuration review (moving from quagga to bird)

[Shahan Agha]

Hi All,

I am working on migrating some systems from quagga to bird and would like
to have some details regarding the filtering and how to set this up.
Currently we are doing inbound bgp filtering based on as-path access-lists,
prefix-lists and communities. Since i dont have much familiarity with Bird
and more familiar with Cisco (quagga is quite similar), i would appreciate
if the Bird configuration can be reviewed,

*Currently on quagga we are doing it the following way:  *
!
neighbor X.X.X.X route-map route-in in
!
route-map route-in permit 10
 match as-path as-in
 set local-preference 99

ip as-path access-list  as-in  permit _ 1234  _
ip as-path access-list  as-in  permit _5678_
!
route-map route-in permit 11
 match community route-in-direct
 set local-preference 110

ip community-list standard  route-in-direct permit 1010:2020
!
route-map route-in  permit 12
 match community  route-in-eu
 set local-preference 121

ip community-list standard  route-in-eu  permit 3030:4040
ip community-list standard  route-in-eu  permit 5050:6060
!
route-map route-in  permit 13
!

*Goals to achieve: *

1. Block my fixed pulic ip address block to be advertised back to me in
order to avoid any sort of loops
2. If some traffic is originated from specific origin ASN like in Cisco
quagga the expression is _ 1234  _ , set their local preference to 110.
This needs to be done for multiple origin ASNs.
3. Route received with one specific community should have its local
preference set to 110
4. Set local preference to 99 matching specific set of communities.

*Future Bird configuration: *

function ebgp_in()
prefix set my_public;
{

#Goal. 1
my_public = [ 12.13.14.0/22+ ];
        if net ~ my_public then return false;

#Goal. 2
if bgp_path ~ [(= * 1234 * =),(= * 4567 * =) ]
bgp_local_pref = 99; }

#Goal. 3
if bgp_community ~ [(1010,2020)] then {
                bgp_local_pref = 110; }

#Goal. 4
        if bgp_community ~ [(3030,4040),(5050,6060)] then {
                bgp_local_pref = 121; }

        return true;
}

I would really appreciate if bird experts could help me with this. ;)

Thanks,
Agha
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