Hi Dariusz, Will ASPATH prepends work for you? Or this feature might help you: https://bird.network.cz/?get_doc&v=20&f=bird-6.html#bgp-aigp
Regards, Alexander Zubkov Qrator Labs On Wed, Sep 13, 2023 at 11:43 AM Mazur, Dariusz via Bird-users <[email protected]> wrote: > > Hello Bird Users, > > Have a question about bgp best path algorithm in Route Refletector > environment and possible fix: > > > > > > Topology ( we use only iBGP with multiply RR): > > r01a.tor ----- r01.leaf.105---r01.spine----r01.leaf108-----r09a.tor > > > > I announce the same block 172.232.0.0/19 from both tors > > > > r01.leaf108 receives 172.232.0.0/19 from r01.spine and r09a.tor, and treat > them as equal path (multipath). > > > > All BGP attributes are equal except of BGP originator id and cluster-list > > > > r01.leaf108.ord02.fab> show route for 172.232.0.0/19 all > > 172.232.0.0/19 > > unicast [192.168.226.56__r01.spine101 > 2023-09-06] * (100) [AS4250527481?] > > via 192.168.226.56 on vlan.101 > > Type: BGP univ > > BGP.origin: Incomplete > > BGP.as_path: 4250527481 > > BGP.next_hop: 192.168.226.56 > > BGP.med: 0 > > BGP.local_pref: 400 > > BGP.atomic_aggr: > > BGP.aggregator: 23.192.121.225 AS4250527481 > > BGP.community: (63949,1000) (63949,1002) (63949,1004) > (63949,1005) (65110,31107) (65310,31107) (65518,31107) > > BGP.originator_id: 23.205.212.134 > > BGP.cluster_list: 23.205.212.8 23.205.212.112 > > > > unicast [192.168.198.35__r09b.tor108 2023-09-06] (100) > [AS4250827489?] > > via 192.168.198.35 on vlan.218 > > Type: BGP univ > > BGP.origin: Incomplete > > BGP.as_path: 4250827489 > > BGP.next_hop: 192.168.198.35 > > BGP.med: 0 > > BGP.local_pref: 400 > > BGP.atomic_aggr: > > BGP.aggregator: 23.213.15.233 AS4250827489 > > BGP.community: (63949,1000) (63949,1002) (63949,1004) > (63949,1005) (65110,31107) (65310,31107) (65518,31107) > > > > Looks like Bird does not check cluster_list length to determine better > route, is it intentional? Can you suggest any possible fix to prefer route > from r09a.tor using cluster-list or anything what is local for router (local > pref is not option because all routers are in the same asn and use iBGP) > > Thanks, > > Dariusz > > > > > >
