BGP selection
Alexandre Corso
alexandre at acorso.fr
Tue Apr 26 04:57:16 CEST 2022
Hello,
I found a strange behaviour on my BIRD route reflector:
BIRD version: 2.0.7
Topology:
------ vrr01_ny2_nyc
RR1 ||
------ vrr01_pa4_par ---- CORE1
I have one route A.A.A.A received via two other Router reflector (vrr01_ny2_nyc / vrr01_pa4_par)
The origin of the route is 185.x.x.x
$ birdc show route A.A.A.A/32 table ipv4_rr all
BIRD 2.0.7 ready.
Table ipv4_rr:
A.A.A.A/32 unicast [ipv4_vrr01_ny2_nyc 00:54:45.006 from 100.100.254.133] * (100/67955) [AS65030?]
via 100.99.0.120 on eth2.666
Type: BGP univ
BGP.origin: Incomplete
BGP.as_path: 64655 65030
BGP.next_hop: 185.x.x.x
BGP.local_pref: 100
BGP.community: (35280,843) (35280,844) (35280,1010) (35280,2060) (35280,3070)
BGP.originator_id: 185.x.x.x
BGP.cluster_list: 0.0.0.21 0.0.0.11
unicast [ipv4_vrr01_pa4_par 2022-04-14 from 100.100.254.134] (100/68045) [AS65030?]
via 100.99.0.120 on eth2.666
Type: BGP univ
BGP.origin: Incomplete
BGP.as_path: 64655 65030
BGP.next_hop: 185.x.x.x
BGP.local_pref: 100
BGP.community: (35280,843) (35280,844) (35280,1010) (35280,2060) (35280,3070)
BGP.originator_id: 185.x.x.x
BGP.cluster_list: 0.0.0.11
I check the metric to 185.x.x.x and I see 67955, but on my second route (learned via vrr01_pa4_par), I see another value (68045)
$ birdc show route 185.x.x.x
BIRD 2.0.7 ready.
Table master4:
185.x.x.x /32 unicast [ospfv2 23:56:36.331] I (150/67955) [185.x.x.x]
via 100.99.0.120 on eth2.666
Can you help me to understand the behaviour?
I don’t understand why the second route is not preferred as the cluster_list is smaller (probably the BGP algorithm in BIRD).
More information
$ birdc show route 100.100.254.133/32
BIRD 2.0.7 ready.
Table master4:
100.100.254.133/32 unicast [ospfv2 2022-04-20] I (150/133525) [100.100.254.133]
via 100.99.0.120 on eth2.666
$ birdc show route 100.100.254.134/32
BIRD 2.0.7 ready.
Table master4:
100.100.254.134/32 unicast [ospfv2 2022-04-20] I (150/132615) [100.100.254.134]
via 100.99.0.120 on eth2.666
Part of the configuration (same for the 2 peers)
protocol bgp ipv4_vrr01_ny2_nyc from IPV4_RR_PEER {
description "IPv4 vrr01.ny2.nyc";
neighbor 100.100.254.133;
ipv4 {
import filter bgp_in_rr_v4;
export filter bgp_full_view_v4;
};
}
protocol bgp ipv4_vrr01_pa4_par from IPV4_RR_PEER {
description "IPv4 vrr01.pa4.par";
neighbor 100.100.254.134;
ipv4 {
import filter bgp_in_rr_v4;
export filter bgp_full_view_v4;
};
}
Does somebody have the full BGP algorithm?
Alexandre Corso
AS35280
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://trubka.network.cz/pipermail/bird-users/attachments/20220426/748c1e52/attachment.htm>
More information about the Bird-users
mailing list