Route Reflection

[jay_7301]

Hi All,

Hoping someone can help my understand my RR setup.

We have 2 RRS with their own unique cluster-id and they do not peer with each other. These 2 RRS server the same clients. 

In this basic setup what is the advantage of having the unique cluster-id vs having the same cluster-id.

Just to add we have routes coming in externally from border/transit routers peering with both the RRs and internal PEs the peer with both the RRs so i'm tryin to understand what is the difference between having the same cluster IDs vs unique Cluster IDs?

Thanks,

Jay

[MHM Cisco World]

https://packetpushers.net/bgp-rr-design-part-1/

for me the cluster-ID important when you interconnect both RR. 
the RR client receive two copy from both RR. 

[jay_7301]

in our setup the RRs don't peer with each other. Would this still be the case the each PE would receive 2 copies? if not then there are other methods for the PE to receive 2 routes like using unique RDs for example.

so our setup is valid so for example 1 RR goes down the other RR will reflect the client routes the difference is the PE would only receive a single copy of the route?

Thanks

[MHM Cisco World]

I already run small lab both case (w and w/o same cluster id )rr client receive two copies from both RR,

As i mention the different if RR is interconnect.

using RD for VPNv4 effect how RR select best path not how PE will receive copy or not.

[MHM Cisco World]

I have free time now, you want from me to run small lab?

[jay_7301]

sure sir thanks.

[MHM Cisco World]

need some info. for lab 
you have CE connect to PE via two Link and advertise same prefix 
this PE is connect to two RR and it reflect the prefix to other PE.
you need to make PE have two copy from same prefix.
is all above right ?

[jay_7301]

this is correct. thanks again.

[MHM Cisco World]

scenario1 (different Cluster-ID different RD)
R1 advertise LO 1.1.1.1 
both R2 & R3 advertise this prefix to R6 
you can see in R6 prefix with two path and select one path 

[MHM Cisco World]

scenario2 (different Cluster-ID same RD)
R1 advertise LO 1.1.1.1 
both R2 & R3 advertise this prefix to R6 
you can see in R6 prefix with one path why?
because you use same RD so the prefix will be 1.1.1.1+1:100 which is same from R2 and R3, the RR by default advertise the best path and since both path same it select one which is via R2 and advertise it to R6. 

[MHM Cisco World]

scenario3 (same Cluster-ID different RD)
R1 advertise LO 1.1.1.1 
both R2 & R3 advertise this prefix to R6 
you can see in R6 prefix with two path and select one path

[MHM Cisco World]

scenario4 (same Cluster-ID same RD)
R1 advertise LO 1.1.1.1 
both R2 & R3 advertise this prefix to R6 
you can see in R6 prefix with one path why?
because you use same RD so the prefix will be 1.1.1.1+1:100 which is same from R2 and R3, the RR by default advertise the best path and since both path same it select one which is via R2 and advertise it to R6.