Duplicated routes received from Route Reflectors

[Chriztoffer Hansen]

On Tue, 2 Feb 2021 at 18:55, Délsio Cabá <delsio at gmail.com> wrote:
> I understand your point. I have added a third RR Server to check, and
> it's adding a entry to the FIB. So if I have even 10 RR, it will add
> 10 entries on the FIB?

Correct 👍 One route entry in the RR client RIB per cluster-id your RR
client has a direct IBGP peering with amongst your RR's.
2 cluster id's → 2 RIB entries.
5 cluster id's → 5 RIB entries.

> Why the cluster list is different?
>
> RR-CLIENT#show ip bgp x.x.x.x
> BGP routing table entry for x.x.x.x/29, version 1028
> Paths: (3 available, best #1, table default)
>   Not advertised to any peer
>   Refresh Epoch 2
>   Local
>     10.10.10.6 (metric 5) from 10.200.2.126 (10.200.2.126)
>       Origin IGP, metric 0, localpref 400, valid, internal, best
>       Originator: 10.10.10.6, Cluster list: 10.200.2.126
>       rx pathid: 0, tx pathid: 0x0
>   Refresh Epoch 1
>   Local
>     10.10.10.6 (metric 5) from 10.200.2.124 (10.200.2.124)
>       Origin IGP, metric 0, localpref 100, valid, internal
>       Community: 2470510602
>       Originator: 10.10.10.6, Cluster list: 10.200.2.124
>       rx pathid: 0, tx pathid: 0
>   Refresh Epoch 1
>   Local
>     10.10.10.6 (metric 5) from 10.200.2.125 (10.200.2.125)
>       Origin IGP, metric 0, localpref 400, valid, internal
>       Community: 2470510602
>       Originator: 10.10.10.6, Cluster list: 10.200.2.125, 0.0.0.1, 10.200.2.126
>       rx pathid: 0, tx pathid: 0

The 3rd entry in your output below the cluster id denotes the RR
learned the route from a peering via another RR cluster (RR).

E.g. RR client → RR (cluster id 10.200.2.126) → RR (cluster id
0.0.0.1) → RR (cluster id 10.200.2.125) → (another) RR client

I presume you have a full-mesh in your test topology between your RR's?

I am no "super" expert on the matter: So i highly encourage you to
(also) read at least a handful of blog posts/articles/videos online.
E.g. https://duckduckgo.com/?q=BGP+route+reflector+cluster → search results.

-- 
Cheers, Chriztoffer