cannot export routes (AS_PATH problem ?)

4 Jan 2019

      Hi,

Using BIRD 1.6.4 I want to do something very basic: export routes to a peer
to allow transit.

for that, I start by adding communities to my received routes, so I can
distinguish the upstream.

import filter {
if !is_martian() && !is_self_net() && from = bgp_next_hop then {
bgp_large_community.add((myas, 100, XX)); #XX for each upstream
accept;
}
else reject;
};

A community is (apparently?) added to each route. I get about 61'000 ipv6
routes from my upstream.

Now I want to export them to "peer1". Here is my export function:

function bgp_export_peer (){
if (myas,100,20) ~ bgp_large_community then return true;
}

here is the problem: it looks like only 123 routes are exported !
bird> show route export peer count
123 of 362489 routes for 61724 networks

Here is an example of an exported route:

2001:9d8:200b::/48 via 2a06:1287:3308:c0c0::1 on peer-mmnetworks [mmnet
22:24:20] * (100) [AS25577i]
        Type: BGP unicast univ
        BGP.origin: IGP
        BGP.as_path: 207149 206499 204893 206313 6724 8560 25577
        BGP.next_hop: 2a0c:b640:fffe:10:192:220:4:2
        BGP.local_pref: 100
        BGP.community: (666,666) (997,6499) (6724,900) (6724,960) (8560,4)
(8560,10000) (57555,0) (57555,4100) (57555,4101) (65010,10000)
        BGP.large_community: (206313, 206313, 206313) (207149, 100, 20)

and an example of a non-exported route:

2406:3003:2032::/48 via 2a06:1287:3308:c0c0::1 on peer-mmnetworks [mmnet
20:48:51] (100) [AS55430i]
        Type: BGP unicast univ
        BGP.origin: IGP
        BGP.as_path: 206499 6939 38861 55430
        BGP.next_hop: 2a06:1287:3308:c0c0::1 fe80::b9d7:d605
        BGP.med: 0
        BGP.local_pref: 100
        BGP.community: (0,2906) (0,6939) (0,12876) (0,12989) (0,13335)
(0,15133) (0,15169) (0,16265) (0,16276) (0,16509) (0,20940) (0,22822)
(0,32934)
        BGP.large_community: (207149, 100, 20)

as you see, my lare community are added on both routes.
The exported route has my AS as the first value on the left (AS_PATH),
which is not the case for the non-exported route.

Logically, all exported routes should have my AS on the left. Am I missing
something? It's probably logical, but I do not understand what's going on
here.
In the same way, I can not export any route that comes from my peers
(direct connection), since they have only their AS in the path.

help would be highly appreciated.
cheers, Julien Sansonnens